Document and Entity Information - USD ($) $ in Billions	12 Months Ended
Document and Entity Information - USD ($) $ in Billions	Dec. 31, 2017	Feb. 16, 2018	Jun. 30, 2017
Document and Entity Information [Abstract]
Entity Registrant Name	MGIC INVESTMENT CORP
Entity Central Index Key	0000876437
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$ 4.1
Entity Common Stock, Shares Outstanding		370,862,190
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	FY
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2017

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Securities, available-for-sale, at fair value:
Fixed income (amortized cost, 2017 - $4,946,278; 2016 - $4,717,211)	$ 4,983,315	$ 4,685,222
Equity securities	7,246	7,128
Total investment portfolio	4,990,561	4,692,350
Cash and cash equivalents	99,851	155,410
Accrued investment income	46,060	44,073
Reinsurance recoverable on loss reserves	48,474	50,493
Reinsurance recoverable on paid losses	3,872	4,964
Premiums receivable	54,045	52,392
Home office and equipment, net	44,936	36,088
Deferred insurance policy acquisition costs	18,841	17,759
Deferred income taxes, net	234,381	607,655
Other assets	78,478	73,345
Total assets	5,619,499	5,734,529
Liabilities:
Loss reserves	985,635	1,438,813
Unearned premiums	392,934	329,737
FHLB Advance	155,000	155,000
Senior notes	418,560	417,406
Convertible senior notes	0	349,461
Convertible junior subordinated debentures	256,872	256,872
Other liabilities	255,972	238,398
Total liabilities	2,464,973	3,185,687
Contingencies
Shareholders' equity:
Common stock (one dollar par value, shares authorized 1,000,000; shares issued 2017 - 370,567; 2016 - 359,400; outstanding 2017 - 370,567; 2016 - 340,663)	370,567	359,400
Paid-in capital	1,850,582	1,782,337
Treasury stock (shares at cost 2016 - 18,737)	0	(150,359)
Accumulated other comprehensive loss, net of tax	(43,783)	(75,100)
Retained earnings	977,160	632,564
Total shareholders' equity	3,154,526	2,548,842
Total liabilities and shareholders' equity	$ 5,619,499	$ 5,734,529

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Fixed income, amortized cost	$ 4,946,278	$ 4,717,211
Shareholders' equity:
Common stock, par value (in dollars per share)	$ 1	$ 1
Common stock, shares authorized (in shares)	1,000,000,000	1,000,000,000
Common stock, shares issued (in shares)	370,567,000	359,400,000
Common stock, shares outstanding (in shares)	370,567,000	340,663,000
Treasury stock, shares at cost (in shares)	0	18,737,000

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Premiums written:
Direct	$ 1,121,776	$ 1,107,923	$ 1,074,490
Assumed	1,905	1,053	1,178
Ceded	(125,726)	(133,885)	(55,391)
Net premiums written	997,955	975,091	1,020,277
Increase in unearned premiums	(63,208)	(49,865)	(124,055)
Net premiums earned	934,747	925,226	896,222
Investment income, net of expenses	120,871	110,666	103,741
Net realized investment gains	249	8,932	28,361
Other revenue	10,187	17,659	12,964
Total revenues	1,066,054	1,062,483	1,041,288
Losses and expenses:
Losses incurred, net	53,709	240,157	343,547
Change in premium deficiency reserve	0	0	(23,751)
Amortization of deferred policy acquisition costs	11,111	9,646	8,789
Other underwriting and operating expenses, net	159,638	150,763	155,577
Interest expense	57,035	56,672	68,932
Loss on debt extinguishment	65	90,531	507
Total losses and expenses	281,558	547,769	553,601
Income before tax	784,496	514,714	487,687
Provision for (benefit from) income taxes	428,735	172,197	(684,313)
Net income	$ 355,761	$ 342,517	$ 1,172,000
Earnings per share:
Basic (in dollars per share)	$ 0.98	$ 1.00	$ 3.45
Diluted (in dollars per share)	$ 0.95	$ 0.86	$ 2.60
Weighted average common shares outstanding - basic (in shares)	362,380	342,890	339,552
Weighted average common shares outstanding - diluted (in shares)	394,766	431,992	468,039
Dividends per share (in dollars per share)	$ 0	$ 0	$ 0

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 27,314	$ 120,027	$ 118,622	$ 89,798	$ 107,487	$ 56,618	$ 109,221	$ 69,191	$ 355,761	$ 342,517	$ 1,172,000
Other comprehensive income (loss), net of tax:
Change in unrealized investment gains and losses									47,547	(3,649)	40,403
Benefit plans adjustment									(5,839)	(9,620)	(15,714)
Foreign currency translation adjustment									31	(951)	(4,228)
Other comprehensive income (loss), net of tax									41,739	(14,220)	20,461
Comprehensive income									$ 397,500	$ 328,297	$ 1,192,461

CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common stock	Paid-in capital	Treasury stock	Accumulated other comprehensive loss	Retained earnings (deficit)
Balance, beginning of year at Dec. 31, 2014		$ 340,047	$ 1,663,592	$ (32,937)	$ (81,341)	$ (852,458)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net common stock issued under share-based compensation plans		50	(478)
Reissuance of treasury stock, net under share-based compensation plans			(6,894)	29,575		(29,495)
Tax benefit from share-based compensation			2,116
Equity compensation			11,902
Other comprehensive income (loss)	$ 20,461				20,461
Net income	1,172,000					1,172,000
Balance, end of year at Dec. 31, 2015	2,236,140	340,097	1,670,238	(3,362)	(60,880)	290,047
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock		18,313	113,146
Net common stock issued under share-based compensation plans		990	(6,020)
Reissuance of treasury stock, net under share-based compensation plans			(130)	130
Tax benefit from share-based compensation			67
Equity compensation			11,373
Reacquisition of convertible junior subordinated debentures-equity component			(6,337)
Purchases of common stock	(147,100)			(147,127)
Other comprehensive income (loss)	(14,220)				(14,220)
Net income	342,517					342,517
Balance, end of year at Dec. 31, 2016	2,548,842	359,400	1,782,337	(150,359)	(75,100)	632,564
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of share-based compensation accounting standard update			49			153
Issuance of common stock		10,386	60,903
Net common stock issued under share-based compensation plans		781	(7,602)
Equity compensation			14,895
Reissuance of treasury stock, net				150,359		(21,740)
Other comprehensive income (loss)	41,739				41,739
Net income	355,761					355,761
Cumulative effect to reclassify certain tax effects from accumulated other comprehensive loss					(10,422)	10,422
Balance, end of year at Dec. 31, 2017	$ 3,154,526	$ 370,567	$ 1,850,582	$ 0	$ (43,783)	$ 977,160

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities:
Net income	$ 355,761	$ 342,517	$ 1,172,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and other amortization	64,430	61,342	52,559
Deferred tax expense (benefit)	355,044	162,356	(692,810)
Net realized investment gains	(249)	(8,932)	(28,361)
Loss on debt extinguishment	65	90,531	507
Change in certain assets and liabilities:
Accrued investment income	(1,987)	(3,849)	(9,706)
Prepaid reinsurance premium	11	101	47,457
Reinsurance recoverable on loss reserves	2,019	(6,006)	13,354
Reinsurance recoverable on paid losses	1,092	(1,645)	3,105
Premiums receivable	(1,653)	(3,923)	8,973
Deferred insurance policy acquisition costs	(1,082)	(2,518)	(3,001)
Profit commission receivable	(2,844)	(747)	64,525
Loss reserves	(453,178)	(454,589)	(503,405)
Premium deficiency reserve	0	0	(23,751)
Unearned premiums	63,197	49,764	76,559
Return premium accrual	(25,400)	(18,800)	(9,600)
Income taxes payable - current	49,178	1,123	2,518
Other, net	2,253	18,035	(9,528)
Net cash provided by operating activities	406,657	224,760	161,395
Purchases of investments:
Fixed income	(1,293,616)	(1,360,386)	(2,462,844)
Equity securities	(79)	(3,197)	(2,623)
Proceeds from sales of fixed income	246,908	728,042	1,796,153
Proceeds from maturity of fixed income	759,212	547,444	559,774
Proceeds from sale of equity securities	0	5,257	0
Net increase in restricted cash	0	0	17,212
Additions to property and equipment	(16,066)	(10,552)	(4,630)
Net cash used in investing activities	(303,641)	(93,392)	(96,958)
Cash flows from financing activities:
Proceeds from revolving credit facility	150,000	0	0
Repayment of revolving credit facility	(150,000)	0	0
Proceeds from issuance of long-term debt	0	573,094	0
Repayment of long-term debt	0	0	(61,953)
Purchase or repayment of convertible senior notes	(145,620)	(363,778)	(11,152)
Payment of original issue discount - convertible senior notes	(4,504)	(11,250)	(345)
Purchase of convertible junior subordinated debentures	0	(100,860)	0
Payment of original issue discount-convertible junior subordinated debentures	0	(41,540)	0
Cash portion of loss on debt extinguishment	0	(59,460)	(507)
Repurchase of common stock	0	(147,127)	0
Payment of debt issuance costs	(1,630)	(1,127)	0
Payment of withholding taxes related to share-based compensation net share settlement	(6,821)	(5,030)	(7,242)
Net cash used in financing activities	(158,575)	(157,078)	(81,199)
Net decrease in cash and cash equivalents	(55,559)	(25,710)	(16,762)
Cash and cash equivalents at beginning of year	155,410	181,120	197,882
Cash and cash equivalents at end of year	$ 99,851	$ 155,410	$ 181,120

Nature of Business	12 Months Ended
Nature of Business	Dec. 31, 2017
Nature of Business [Abstract]
Nature of Business	Nature of Business MGIC Investment Corporation is a holding company which, through Mortgage Guaranty Insurance Corporation ("MGIC"), is principally engaged in the mortgage insurance business. We provide mortgage insurance to lenders throughout the United States and to government sponsored entities to protect against loss from defaults on low down payment residential mortgage loans. Our principal product is primary mortgage insurance. Primary mortgage insurance provides mortgage default protection on individual loans and covers unpaid loan principal, delinquent interest and certain expenses associated with the default and subsequent foreclosure or sale approved by us. Through certain non-insurance subsidiaries, we also provide various services for the mortgage finance industry, such as contract underwriting, analysis of loan originations and portfolios, and mortgage lead generation. An insurance subsidiary of MGIC provides credit insurance for certain mortgages under Fannie Mae and Freddie Mac (the "GSEs") credit risk transfer programs in transactions entered into in 2016. At December 31, 2017, our direct domestic primary insurance in force ("IIF") was $194.9 billion, which represents the principal balance in our records of all mortgage loans that we insure, and our direct domestic primary risk in force ("RIF") was $50.3 billion, which represents the IIF multiplied by the insurance coverage percentage. Substantially all of our insurance written since 2008 has been for loans purchased by the GSEs. We operate under the Private Mortgage Insurer Eligibility Requirements ("PMIERs") of the GSEs that became effective December 31, 2015 and which have been amended from time to time. The financial requirements of the PMIERs require a mortgage insurer’s "Available Assets" (generally only the most liquid assets of an insurer) to equal or exceed its "Minimum Required Assets" (which are based on an insurer's book, calculated from tables of factors with several risk dimensions and subject to a floor amount). Based on our interpretation of the PMIERs, as of December 31, 2017, MGIC’s Available Assets are in excess of its Minimum Required Assets; and MGIC is in compliance with the financial requirements of the PMIERs and eligible to insure loans purchased by the GSEs.

Basis of Presentation	12 Months Ended
Basis of Presentation	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation Basis of presentation The accompanying consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America ("GAAP"), as codified in the Accounting Standards Codification ("ASC"). Our consolidated financial statements include the accounts of MGIC Investment Corporation and its majority-owned subsidiaries. Intercompany transactions and balances have been eliminated. In accordance with GAAP, we are required to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting periods. Actual results could differ from those estimates. We have considered subsequent events through the date of this filing. Reclassifications Certain reclassifications to 2016 and 2015 amounts have been made in the accompanying consolidated financial statements to conform to the 2017 presentation. See Note 3 - "Significant Accounting Policies" for a discussion of our adoption of accounting guidance in 2017 that resulted in other reclassifications.

Significant Accounting Policies

12 Months Ended

Dec. 31, 2017

Accounting Policies [Abstract]

Significant Accounting Policies

Cash and Cash Equivalents

We consider money market funds and investments with original maturities of three months or less to be cash equivalents.

Fair value measurements

The authoritative accounting guidance includes a framework for measuring fair value. Fair value is disclosed using a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value and includes Levels 1, 2, and 3. To determine the fair value of securities available-for-sale in Level 1 and Level 2 of the fair value hierarchy, independent pricing sources have been utilized. One price is provided per security based on observable market data. To ensure securities are appropriately classified in the fair value hierarchy, we review the pricing techniques and methodologies of the independent pricing sources and believe that their policies adequately consider market activity, either based on specific transactions for the issue valued or based on modeling of securities with similar credit quality, duration, yield and structure that were recently traded. A variety of inputs are utilized by the independent pricing sources including benchmark yields, reported trades, non-binding broker/dealer quotes, issuer spreads, two sided markets, benchmark securities, bids, offers and reference data including data published in market research publications. Inputs may be weighted differently for any security, and not all inputs are used for each security evaluation.

Market indicators, industry and economic events are also considered. This information is evaluated using a multidimensional pricing model. This model combines all inputs to arrive at a value assigned to each security. Quality controls are performed by the independent pricing sources throughout this process, which include reviewing tolerance reports, trading information, data changes, and directional moves compared to market moves. In addition, on a quarterly basis, we perform quality controls over values received from the pricing sources which also include reviewing tolerance reports, trading information, data changes, and directional moves compared to market moves. We have not made any adjustments to the prices obtained from the independent pricing sources.

In accordance with fair value accounting guidance, we applied the following fair value hierarchy in order to measure fair value for assets and liabilities:

Level 1 - Quoted prices for identical instruments in active markets that we can access. Financial assets utilizing Level 1 inputs primarily include U.S. Treasury securities and certain equity securities.

Level 2 - Quoted prices for similar instruments in active markets that we can access; quoted prices for identical or similar instruments in markets that are not active; and inputs, other than quoted prices, that are observable in the marketplace for the instrument. The observable inputs are used in valuation models to calculate the fair value of the instruments. Financial assets utilizing Level 2 inputs primarily include obligations of U.S. government corporations and agencies, corporate bonds, mortgage-backed securities, asset-backed securities, and most municipal bonds.

The independent pricing sources utilize these approaches to determine the fair value of the instruments in Level 2 of the fair value hierarchy based on type of instrument:

Corporate Debt & U.S. Government and Agency Bonds are evaluated by surveying the dealer community, obtaining relevant trade data, benchmark quotes and spreads and incorporating this information into the evaluation process.

Obligations of U.S. States & Political Subdivisions are evaluated by tracking, capturing, and analyzing quotes for active issues and trades reported via the Municipal Securities Rulemaking Board records. Daily briefings and reviews of current economic conditions, trading levels, spread relationships, and the slope of the yield curve provide further data for evaluation.

Residential Mortgage-Backed Securities ("RMBS") are evaluated by monitoring interest rate movements, and other pertinent data daily. Incoming market data is enriched to derive spread, yield and/or price data as appropriate, enabling known data points to be extrapolated for valuation application across a range of related securities.

Commercial Mortgage-Backed Securities ("CMBS") are evaluated using valuation techniques that reflect market participants’ assumptions and maximize the use of relevant observable inputs including quoted prices for similar assets, benchmark yield curves and market corroborated inputs. Evaluation utilizes regular reviews of the inputs for securities covered, including executed trades, broker quotes, credit information, collateral attributes and/or cash flow waterfall as applicable.

Asset-Backed Securities ("ABS") are evaluated using spreads and other information solicited from market buy-and-sell-side sources, including primary and secondary dealers, portfolio managers, and research analysts. Cash flows are generated for each tranche, benchmark yields are determined, and deal collateral performance and tranche level attributes including trade activity, bids, and offers are applied, resulting in tranche specific prices.

Collateralized loan obligations ("CLO") Collateralized Loan Obligations are evaluated by manager rating, seniority in the capital structure, assumptions about prepayment, default and recovery and their impact on cash flow generation. Loan level net asset values are determined and aggregated for tranches and as a final step prices are checked against available recent trade activity.

Level 3 - Valuations derived from valuation techniques in which one or more significant inputs or value drivers are unobservable or, for certain equity securities, from their par value due to restrictions that require them to be redeemed or sold only to the security issuer at par value. The inputs used to derive the fair value of Level 3 securities reflect our own assumptions about the assumptions a market participant would use in pricing an asset or liability. Our non-financial assets that are classified as Level 3 securities consist of real estate acquired through claim settlement. The fair value of real estate acquired is the lower of our acquisition cost or a percentage of the appraised value. The percentage applied to the appraised value is based upon our historical sales experience adjusted for current trends.

Investments

Our entire investment portfolio is classified as available-for-sale and is reported at fair value or, for certain equity securities carried at cost, amounts that approximate fair value. The related unrealized investment gains or losses are, after considering the related tax expense or benefit, recognized as a component of accumulated other comprehensive income (loss) in shareholders' equity. Realized investment gains and losses are reported in income based upon specific identification of securities sold. (See Note 5 – “Investments.”)

Each quarter we perform reviews of our investments in order to determine whether declines in fair value below amortized cost were considered other-than-temporary. In evaluating whether a decline in fair value is other-than-temporary, we consider several factors including, but not limited to:


▪	our intent to sell the security or whether it is more likely than not that we will be required to sell the security before recovery of its amortized cost basis;


▪	the present value of the discounted cash flows we expect to collect compared to the amortized cost basis of the security;


▪	extent and duration of the decline;


▪	failure of the issuer to make scheduled interest or principal payments;


▪	change in rating below investment grade; and


▪	adverse conditions specifically related to the security, an industry, or a geographic area.

Based on our evaluation, we will record an other-than-temporary impairment ("OTTI") adjustment on a security if we intend to sell the impaired security, if it is more likely than not that we will be required to sell the impaired security prior to recovery of its amortized cost basis, or if the present value of the discounted cash flows we expect to collect is less than the amortized cost basis of the security. If the fair value of a security is below its amortized cost at the time of our intent to sell, the security is classified as other-than-temporarily impaired and the full amount of the impairment is recognized as a loss in the statement of operations. Otherwise, when a security is considered to be other-than-temporarily impaired, the losses are separated into the portion of the loss that represents the credit loss and the portion that is due to other factors. The credit loss portion is recognized as a loss in the statement of operations, while the loss due to other factors is recognized in accumulated other comprehensive loss, net of taxes. A credit loss is determined to exist if the present value of the discounted cash flows, using the security’s original yield, expected to be collected from the security is less than the cost basis of the security.

Home office and equipment

Home office and equipment is carried at cost net of depreciation. For financial reporting purposes, depreciation is determined on a straight-line basis for the home office and equipment over estimated lives ranging from 3 to 45 years. For income tax purposes, we use accelerated depreciation methods.

Home office and equipment is shown net of accumulated depreciation of $33.9 million, $30.6 million and $26.1 million as of December 31, 2017, 2016 and 2015, respectively. Depreciation expense for the years ended December 31, 2017, 2016 and 2015 was $5.4 million, $4.6 million and $3.2 million, respectively.

Deferred Insurance Policy Acquisition Costs

Costs directly associated with the successful acquisition of mortgage insurance business, consisting of employee compensation and other policy issuance and underwriting expenses, are initially deferred and reported as deferred insurance policy acquisition costs ("DAC"). The deferred costs are net of any ceding commissions received associated with our reinsurance agreements. For each underwriting year of business, these costs are amortized to income in proportion to estimated gross profits over the estimated life of the policies. We utilize anticipated investment income in our calculation. This includes accruing interest on the unamortized balance of DAC. The estimates for each underwriting year are reviewed quarterly and updated when necessary to reflect actual experience and any changes to key variables such as persistency or loss development.

Loss Reserves

Reserves are established for insurance losses and loss adjustment expenses ("LAE") when we receive notices of default on insured mortgage loans. We consider a loan in default when it is two or more payments past due. Even though the accounting standard, ASC 944, regarding accounting and reporting by insurance entities specifically excludes mortgage insurance from its guidance relating to loss reserves, we establish loss reserves using the general principles contained in the insurance standard. However, consistent with industry standards for mortgage insurers, we do not establish loss reserves for future claims on insured loans which are not currently in default. Loss reserves are established by estimating the number of loans in our inventory of delinquent loans that will result in a claim payment, which is referred to as the claim rate, and further estimating the amount of the claim payment, which is referred to as claim severity. Our loss estimates are established based upon historical experience, including rescissions of policies, curtailments of claims, and loan modification activity. Adjustments to reserve estimates are reflected in the financial statements in the years in which the adjustments are made. The liability for reinsurance assumed is based on information provided by the ceding companies.

Reserves are also established for estimated losses from defaults occurring prior to the close of an accounting period on notices of default not yet reported to us. These incurred but not reported ("IBNR") reserves are also established using estimated claim rates and claim severities.

Reserves are also established for the estimated costs of settling claims, including legal and other expenses and general expenses of administering the claims settlement process. Reserves are also ceded to reinsurers under our reinsurance agreements. (See Note 8 – “Loss Reserves” and Note 9 – “Reinsurance.”)

Premium Deficiency Reserve

After our loss reserves are initially established, we perform premium deficiency tests using our best estimate assumptions as of the testing date. Premium deficiency reserves are established, if necessary, when the present value of expected future losses and expenses exceeds the present value of expected future premium and already established reserves. Products are grouped for premium deficiency testing purposes based on similarities in the way the products are acquired, serviced and measured for profitability.

The calculation of premium deficiency reserves requires the use of significant judgments and estimates to determine the present value of future premium and present value of expected losses and expenses on our business. Similar to our loss reserve estimates, our estimates for premium deficiency reserves could be adversely affected by several factors discussed in Note 8 - Loss Reserves. To the extent premium patterns and actual loss experience differ from the assumptions used in calculating the premium deficiency reserves, the differences between the actual results and our estimate will affect future period earnings and could be material.

We established a premium deficiency reserve in 2007 on our Wall Street Bulk business, which we also ceased writing in that year. The premium deficiency reserve was eliminated in 2015 and our consolidated statement of operations for the year ended December 31, 2015 was affected by a decrease in our premium deficiency reserves of $24 million.

Revenue Recognition

We write policies which are guaranteed renewable contracts at the insured's option on a monthly, single, or annual premium basis. We have no ability to reunderwrite or reprice these contracts. Premiums written on monthly premium policies are earned as coverage is provided. Premiums written on single premium policies and annual premium policies are initially deferred as unearned premium reserve and earned over the estimated policy life. Premiums written on single premium policies are amortized over the policy life in relationship to the anticipated incurred loss pattern based on historical experience. Premiums written on annual premium policies are earned on a monthly pro rata basis. When a policy is cancelled for a reason other than rescission or claim payment, all premium that is non-refundable is immediately earned. Any refundable premium is returned to the servicer or borrower. When a policy is cancelled due to rescission, all previously collected premium is returned to the servicer and when a policy is cancelled because a claim is paid, premium collected since the date of default is returned. The liability associated with our estimate of premium to be returned is accrued for separately and included in "Other liabilities" on our consolidated balance sheets. When a premium deficiency exists the premium refund liability is included in “Premium deficiency reserves” on our consolidated balance sheets. Changes in these liabilities affect premiums written and earned and change in premium deficiency reserve, respectively. The actual return of premium for all periods affects premiums written and earned.

Fee income of our non-insurance subsidiaries is earned and recognized as the services are provided and the customer is obligated to pay. Fee income consists primarily of contract underwriting and related fee-based services provided to lenders and is included in “Other revenue” on the consolidated statements of operations.

Income Taxes

Deferred income taxes are provided under the liability method, which recognizes the future tax effects of temporary differences between amounts reported in the consolidated financial statements and the tax bases of these items. The expected tax effects are computed at the enacted regular federal statutory tax rate. Using this method, we have recorded a net deferred tax asset primarily due to net operating losses incurred in prior years. During 2017, net deferred tax assets were remeasured at the lower corporate tax rate enacted under the U.S. tax reform legislation signed into law in the fourth quarter of 2017 (the "Tax Act"). See Note 12- "Income Taxes" for discussion of the impact of the Tax Act on our consolidated financial statements.

On a quarterly basis, we review the need to maintain a deferred tax asset valuation allowance as an offset to the net deferred tax asset, before valuation allowance. We analyze several factors, among which are the severity and frequency of operating losses, our capacity for the carryback or carryforward of any losses, the existence and current level of taxable operating income, operating results on a three year cumulative basis, the expected occurrence of future income or loss, the expiration dates of the carryforwards, the cyclical nature of our operating results, and available tax planning strategies. Based on our analysis, we reduced our benefit from income tax through the recognition of a valuation allowance from the first quarter of 2009 through the second quarter of 2015. In the third quarter of 2015, as discussed in Note 12 – “Income Taxes,” we concluded that it was more likely than not that our deferred tax assets would be fully realizable and we reversed the valuation allowance.

We provide for uncertain tax positions and the related interest and penalties based on our assessment of whether a tax benefit is more likely than not to be sustained under any examination by taxing authorities.

Benefit Plans

We have a non-contributory defined benefit pension plan covering substantially all employees, as well as a supplemental executive retirement plan. Retirement benefits are based on compensation and years of service. We recognize these retirement benefit costs over the period during which employees render the service that qualifies them for benefits. Our policy is to fund pension cost as required under the Employee Retirement Income Security Act of 1974.

We offer both medical and dental benefits for retired domestic employees, their eligible spouses and dependents until the retiree reaches the age of 65. Under the plan retirees pay a premium for these benefits. We accrue the estimated costs of retiree medical and dental benefits over the period during which employees render the service that qualifies them for benefits. (See Note 11 – “Benefit Plans.”)

Reinsurance

Loss reserves and unearned premiums are reported before taking credit for amounts ceded under reinsurance agreements. Ceded loss reserves are reflected as "Reinsurance recoverable on loss reserves." Ceded unearned premiums are included in “Other assets.” Amounts due from reinsurers on paid claims are reflected as “Reinsurance recoverable on paid losses.” Ceded premiums payable are included in “Other liabilities.” Any profit commissions are included with “Premiums written – Ceded” and any ceding commissions are included with “Other underwriting and operating expenses, net.” We remain liable for all insurance ceded. (See Note 9 – “Reinsurance.”)

Share-Based Compensation

We have certain share-based compensation plans. Under the fair value method, compensation cost is measured at the grant date based on the fair value of the award and is recognized over the service period which generally corresponds to the vesting period. Awards under our plans generally vest over periods ranging from one to three years. (See Note 15 – “Share-based Compensation Plans.”)

Earnings per Share

Basic earnings per share ("EPS") is calculated by dividing net income by the weighted average number of shares of common stock outstanding. The computation of basic EPS includes as "participating securities" an immaterial number of unvested share-based compensation awards that contain non-forfeitable rights to dividends or dividend equivalents, whether paid or unpaid, under the "two-class" method. Our participating securities are composed of vested restricted stock and restricted stock units ("RSUs") with non-forfeitable rights to dividends (of which none have been declared since the issuance of these participating securities). Diluted EPS includes the components of basic EPS and also gives effect to dilutive common stock equivalents. We calculate diluted EPS using the treasury stock method and if-converted method. Under the treasury stock method, diluted EPS reflects the potential dilution that could occur if our unvested restricted stock units result in the issuance of common stock. Under the if-converted method, diluted EPS reflects the potential dilution that could occur if our convertible debt instruments result in the issuance of common stock. The determination of potentially issuable shares does not consider the satisfaction of the conversion requirements and the shares are included in the determination of diluted EPS as of the beginning of the period, if dilutive. In addition to our 9% Debentures, of which a portion remain outstanding, we previously had several senior note debt issuances that could have resulted in contingently issuable shares and we considered each potential issuance of shares separately to reflect the maximum potential dilution for the period the debt issuances were outstanding. For purposes of calculating basic and diluted EPS, vested restricted stock and RSUs are considered outstanding.

Related party transactions

There were no related party transactions during 2017, 2016 or 2015.

Recent accounting and reporting developments

Accounting standards effective in 2017, or early adopted, and relevant to our financial statements

Table 3.1 shows the relevant amendments to accounting standards that have been implemented for the fiscal year beginning January 1, 2017; none had a material impact on our consolidated financial statements or disclosures.



	Table	3.1
Standard / Interpretation					Effective date
Standard / Interpretation	Amended Standards
	ASC 220		Income Statement - Reporting Comprehensive Income
			•	ASU 2018-02 - Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income	January 1, 2019
	ASC 718		Compensation - Stock Compensation
			•	ASU 2016-09 - Improvements to Employee Share-Based Compensation Accounting	January 1, 2017

Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income

In February 2018, the Financial Accounting Standards Board ("FASB") issued updated guidance that allows an election to reclassify stranded tax effects resulting from the Tax Act's newly enacted federal corporate income tax rate of 21% from accumulated other comprehensive income to retained earnings in an amount that reflects the effect of the change in tax rate on the gross deferred tax amounts and related valuation allowances, if any, at the date of the enactment of the Tax Act related to items remaining in accumulated comprehensive income (loss). Other than the effect of the change in tax rate, we have no other income tax effects related to the application of the Tax Act that are reclassified from accumulated other comprehensive income (loss) to retained earnings. Absent the updated guidance, we generally would remove stranded tax effects lodged in accumulated other comprehensive income (loss) at the time the circumstances under which these tax effects originally arose no longer exist. The updated guidance is effective for annual periods beginning after December 15, 2018, including interim periods within those annual periods. Early adoption is permitted and we adopted this guidance electing to reclass stranded tax effects from the Tax Act to retained earnings for the fourth quarter ending December 31, 2017.

◦

Adoption impact: We recorded a cumulative effect adjustment that reclassified $10.4 million from accumulated other comprehensive loss to retained earnings to reflect the difference between the amount initially credited to other comprehensive income (loss) and the amount that would have been credited at the newly enacted federal corporate tax rate. The effect of this reclassification increases our retained earnings and increases our accumulated other comprehensive loss, with no change to our total shareholders' equity as of December 31, 2017.

Improvements to Employee Share-Based Compensation Accounting

In March 2016, the FASB issued updated guidance that simplifies several aspects of the accounting for employee share-based compensation including the accounting for income taxes, forfeitures, and statutory tax withholding requirements, as well as classification of related amounts within the statement of cash flows. Specifically, the updated guidance requires the following:


•	Tax effects related to share-based compensation are made through the statement of operations at the time of settlement instead of recognizing them in paid-in capital.


◦	Adoption impact: We recognized discrete tax benefits of $1.6 million in the provision for income taxes on our statement of operations for the year ended December 31, 2017 related to excess tax benefits upon vesting of share-based awards during the period.


•	Recognition of a tax benefit is no longer required to be delayed until it reduces current taxes payable.

◦

Adoption impact: We recognized an immaterial cumulative effect adjustment in opening retained earnings as of January 1, 2017 related to the recognition of a deferred tax asset related to suspended tax benefits from vesting transactions occurring in prior years and from the elimination of our forfeiture estimate on share-based awards, which was previously applied only to awards with service conditions.


•	Tax related cash flows resulting from share-based compensation are to be reported as operating activities on the statement of cash flows, instead of as an inflow from financing activities and an outflow from operating activities.


◦	Adoption impact: We reclassified excess tax benefits related to share-based compensation for 2016 and 2015 to operating activities from financing activities.


•	Shares withheld by an employer for tax-withholding purposes upon vesting of equity compensation represents a cash outflow required to be classified as a financing activity on the statements of cash flows.


◦	Adoption impact: We reclassified employee taxes paid for withheld shares for 2016 and 2015 to financing activities from operating activities.

The update also allows, for tax withholding purposes, entities to withhold an amount of shares up to the employee’s maximum individual tax rate (as opposed to the minimum statutory tax rate) in the relevant jurisdiction without resulting in liability classification of the award. A change in tax withholding is to be applied on a modified retrospective approach.

Prospective Accounting Standards

Table 3.2 shows the relevant new amendments to accounting standards, which are not yet effective or adopted.



	Table	3.2
Standard / Interpretation					Effective date
Standard / Interpretation	Amended Standards
	ASC 718		Compensation - Stock Compensation
			•	ASU 2017-09 - Scope of Modification Accounting	January 1, 2018
	ASC 715		Compensation - Retirement Benefits
			•	ASU 2017-07 - Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost	January 1, 2018
	ASC 310		Receivables - Nonrefundable Fees and Other Costs
			•	ASU 2017-08 - Premium Amortization on Purchased Callable Debt Securities	January 1, 2019
	ASC 326		Financial Instruments - Credit Losses
			•	ASU 2016-13 - Measurement of Credit Losses on Financial Instruments	January 1, 2020
	ASC 825		Financial Instruments - Overall
			•	ASU 2016-01 - Recognition and Measurement of Financial Assets and Financial Liabilities	January 1, 2018

Stock Compensation - Scope of Modification Accounting

In May 2017, the FASB issued updated guidance related to a change in the terms or conditions (modification) of a share-based award. The updated guidance provides that an entity should account for the effects of a modification unless the fair value and vesting conditions of the modified award and the classification of the award (equity or liability instrument) are the same as the original award immediately before the modification. The updated guidance addresses the current diversity in practice on applying modification accounting, as some entities evaluate whether changes to awards are substantive, which is not prescribed within the current accounting guidance. The updated guidance is effective for annual periods beginning after December 15, 2017, including interim periods within those annual periods. We are currently evaluating the impacts the adoption of this guidance will have on our consolidated financial statements, but do not expect it to have a material impact on our consolidated financial statements or disclosures.

Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost

In March 2017, the FASB issued updated guidance that improves the reporting of net benefit cost in the financial statements. The updated guidance requires that an employer report the service cost component in the same financial statement caption as other compensation costs arising from services rendered by employees during the period. The other components of net benefit cost are required to be presented in the statement of operations separately from the service cost component and outside a subtotal of income from operations, if one is presented. Current guidance does not prescribe where the amount of net benefit cost should be presented in an employer’s statement of operations and does not require entities to disclose by line item the amount of net benefit cost that is included in the statement of operations. The updated guidance is effective for annual periods beginning after December 15, 2017, including interim periods within those annual periods. We are currently evaluating the impacts the adoption of this guidance will have on our consolidated financial statements, but do not expect it to have a material impact on our consolidated financial statements or disclosures.

Premium Amortization on Purchased Callable Debt Securities

In March 2017, the FASB issued updated guidance to amend the amortization period for premiums on certain purchased callable debt securities, shortening the amortization period to the earliest call date. Under current GAAP, there is diversity in practice in the amortization period for premiums of callable debt securities and in how the potential for exercise of a call is factored into current impairment assessments. This updated guidance aligns with how callable debt securities, in the United States, are generally quoted, priced, and traded, which incorporates consideration of calls (also referred to as “yield-to-worst” pricing). The updated guidance is effective for annual periods beginning after December 15, 2018, including interim periods within those annual periods. Early adoption is permitted, including adoption in an interim period. We are currently evaluating the impacts the adoption of this guidance will have on our consolidated financial statements, but do not expect it to have a material impact on our consolidated financial statements or disclosures. We currently account for premium amortization on our purchased callable debt securities on a yield-to-worst basis, which generally aligns with the earliest call date.

Measurement of Credit Losses on Financial Instruments

In June 2016, the FASB issued updated guidance that requires immediate recognition of estimated credit losses expected to occur over the remaining life of many financial instruments. Entities will be required to utilize a current expected credit losses (“CECL”) methodology that incorporates their forecasts of future economic conditions into their loss estimate unless such forecasts are not reasonable and supportable, in which case the entity will revert to historical loss experience. Any allowance for CECL reduces the amortized cost basis of the financial instrument to the amount an entity expects to collect. Credit losses relating to available-for-sale fixed maturity securities are to be recorded through an allowance for credit losses, rather than a write-down of the asset, with the amount of the allowance limited to the amount by which fair value is less than amortized cost. In addition, the length of time a security has been in an unrealized loss position will no longer impact the determination of whether a credit loss exists. The updated guidance is not prescriptive about certain aspects of estimating expected credit losses, including the specific methodology to use, and therefore will require significant judgment in application. The updated guidance is effective for annual periods beginning after December 15, 2019, including interim periods within those annual periods. Early adoption is permitted for annual and interim periods in fiscal years beginning after December 15, 2018. We are currently evaluating the impacts the adoption of this guidance will have on our consolidated financial statements, but do not expect it to have a material impact on our consolidated financial statements or disclosures.

Recognition and Measurement of Financial Assets and Financial Liabilities

In January 2016, the FASB issued updated guidance to address the recognition, measurement, presentation, and disclosure of certain financial instruments. The updated guidance requires equity investments, except those accounted for under the equity method of accounting, that have a readily determinable fair value to be measured at fair value with changes in fair value recognized in net income. Equity investments that do not have readily determinable fair values may be remeasured at fair value either upon the occurrence of an observable price change or upon identification of an impairment. A qualitative assessment for impairment is required for equity investments without readily determinable fair values. The updated guidance also eliminates the requirement to disclose the method and significant assumptions used to estimate the fair value of financial instruments measured at amortized cost on the balance sheet. Further, the updated guidance clarifies that entities should evaluate the need for a valuation allowance on a deferred tax asset related to available-for-sale securities in combination with the entity's other deferred tax assets. The updated guidance is effective for annual periods beginning after December 15, 2017, including interim periods within those annual periods and will require recognition of a cumulative effect adjustment at adoption. We do not currently expect the adoption of this guidance to impact our consolidated financial statements or disclosures.

Earnings per Share

12 Months Ended

Dec. 31, 2017

Earnings Per Share [Abstract]

Earnings per Share

Earnings Per Share

Table 4.1 reconciles basic and diluted EPS amounts:



	Table	4.1
Earnings per share			Years Ended December 31,
Earnings per share	(In thousands, except per share data)		2017		2016		2015
	Basic earnings per share:
	Net income		$	355,761	$	342,517	$	1,172,000
	Weighted average common shares outstanding - basic		362,380		342,890		339,552
	Basic earnings per share		$	0.98	$	1.00	$	3.45
	Diluted earnings per share:
	Net income		$	355,761	$	342,517	$	1,172,000
	Interest expense, net of tax ⁽¹⁾:
	2% Notes		907		6,111		7,928
	5% Notes		1,709		6,362		12,228
	9% Debentures		15,027		15,893		22,786
	Diluted income available to common shareholders		$	373,404	$	370,883	$	1,214,942
	Weighted-average shares - Basic		362,380		342,890		339,552
	Effect of dilutive securities:
	Unvested restricted stock units		1,493		1,470		2,113
	2% Notes		8,317		54,450		71,917
	5% Notes		3,548		13,107		25,603
	9% Debentures		19,028		20,075		28,854
	Weighted average common shares outstanding - diluted		394,766		431,992		468,039
	Diluted income per share		$	0.95	$	0.86	$	2.60


⁽¹⁾	Interest expense for the years ended December 31, 2017, 2016 and 2015 has been tax effected at a rate of 35%.

The computation of diluted EPS for the years ended December 31, 2017, 2016, and 2015 includes weighted average unvested restricted stock units outstanding of 1.5 million, 1.5 million, and 2.1 million, respectively.

For the years ended December 31, 2017, 2016, and 2015, all of our then outstanding Convertible Senior Notes and Convertible Junior Subordinated Debentures are reflected in diluted earnings per share using the “if-converted” method. Under this method, if dilutive, the common stock related to the outstanding Convertible Senior Notes and/or Convertible Junior Debentures is assumed issued as of the beginning of the reporting period and the related interest expense, net of tax, is added back to earnings in calculating diluted EPS.

Investments

12 Months Ended

Dec. 31, 2017

Investments [Abstract]

Investments

The amortized cost, gross unrealized gains and losses and fair value of the investment portfolio as of December 31, 2017 and 2016 are shown below:



	Table	5.1a
Details of investments by category - current year			December 31, 2017
Details of investments by category - current year	(In thousands)		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses ⁽¹⁾			Fair Value
	U.S. Treasury securities and obligations of U.S. government corporations and agencies		$	179,850	$	274	$	(1,278	)	$	178,846
	Obligations of U.S. states and political subdivisions		2,105,063		56,210		(8,749		)	2,152,524
	Corporate debt securities		2,065,475		10,532		(9,169		)	2,066,838
	ABS		4,925		—		(2		)	4,923
	RMBS		189,153		60		(7,364		)	181,849
	CMBS		301,014		1,204		(4,906		)	297,312
	CLOs		100,798		304		(79		)	101,023
	Total debt securities		4,946,278		68,584		(31,547		)	4,983,315
	Equity securities		7,223		39		(16		)	7,246
	Total investment portfolio		$	4,953,501	$	68,623	$	(31,563	)	$	4,990,561



	Table	5.1b
Details of investments by category - prior year			December 31, 2016
Details of investments by category - prior year	(In thousands)		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses ⁽¹⁾			Fair Value
	U.S. Treasury securities and obligations of U.S. government corporations and agencies		$	73,847	$	407	$	(724	)	$	73,530
	Obligations of U.S. states and political subdivisions		2,147,458		20,983		(25,425		)	2,143,016
	Corporate debt securities		1,756,461		6,059		(18,610		)	1,743,910
	ABS		59,519		74		(28		)	59,565
	RMBS		231,733		102		(7,626		)	224,209
	CMBS		327,042		769		(7,994		)	319,817
	CLOs		121,151		226		(202		)	121,175
	Total debt securities		4,717,211		28,620		(60,609		)	4,685,222
	Equity securities		7,144		8		(24		)	7,128
	Total investment portfolio		$	4,724,355	$	28,628	$	(60,633	)	$	4,692,350


⁽¹⁾	There were no OTTI losses recorded in other comprehensive (loss) income as of December 31, 2017 and 2016.

As discussed in Note 7 - "Debt" we are required to pledge collateral of at least 102% of the outstanding principal balance of the FHLB Advance. As of December 31, 2017, that collateral is included in our total investment portfolio amount shown above with a total fair value of $166.9 million.

We had $13.6 million of investments at fair value on deposit with various states as of December 31, 2017 and 2016, respectively, due to regulatory requirements of those state insurance departments.

Table 5.2 compares the amortized cost and fair values of debt securities, by contractual maturity, as of December 31, 2017.



	Table	5.2
Debt securities maturity schedule			December 31, 2017
	(In thousands)		Amortized Cost		Fair Value
	Due in one year or less		$	541,755	$	541,695
	Due after one year through five years		1,547,712		1,544,943
	Due after five years through ten years		925,751		929,883
	Due after ten years		1,335,170		1,381,687
			4,350,388		4,398,208

	ABS		4,925		4,923
	RMBS		189,153		181,849
	CMBS		301,014		297,312
	CLOs		100,798		101,023
	Total as of December 31, 2017		$	4,946,278	$	4,983,315

The analysis in table 5.2 is based upon contractual maturity. Actual maturities may differ from contractual maturities because certain borrowers have the right to call or prepay certain obligations with or without call or prepayment penalties. Because most mortgage and asset-backed securities provide for periodic payments throughout their lives, they are listed separately in the table.

Tables 5.3a and 5.3b show the components of our unrealized losses on our investment portfolio in the amount of $32 million and $61 million as of December 31, 2017 and 2016, respectively.



	Table	5.3a
Investments unrealized losses - current year	December 31, 2017		Less Than 12 Months					12 Months or Greater					Total
Investments unrealized losses - current year	(In thousands)		Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
	U.S. Treasury securities and obligations of U.S. government corporations and agencies		$	144,042	$	(796	)	$	31,196	$	(482	)	$	175,238	$	(1,278	)
	Obligations of U.S. states and political subdivisions		505,311		(3,624		)	211,684		(5,125		)	716,995		(8,749		)
	Corporate debt securities		932,350		(4,288		)	200,716		(4,881		)	1,133,066		(9,169		)
	ABS		4,923		(2		)	—		—			4,923		(2		)
	RMBS		14,979		(280		)	166,329		(7,084		)	181,308		(7,364		)
	CMBS		51,096		(358		)	138,769		(4,548		)	189,865		(4,906		)
	CLOs		14,243		(7		)	3,568		(72		)	17,811		(79		)
	Equity securities		226		(2		)	431		(14		)	657		(16		)
	Total investment portfolio		$	1,667,170	$	(9,357	)	$	752,693	$	(22,206	)	$	2,419,863	$	(31,563	)



	Table	5.3b
Investments unrealized losses - prior year	December 31, 2016		Less Than 12 Months					12 Months or Greater					Total
Investments unrealized losses - prior year	(In thousands)		Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
	U.S. Treasury securities and obligations of U.S. government corporations and agencies		$	48,642	$	(724	)	$	—	$	—		$	48,642	$	(724	)
	Obligations of U.S. states and political subdivisions		1,136,676		(24,918		)	13,681		(507		)	1,150,357		(25,425		)
	Corporate debt securities		915,777		(16,771		)	35,769		(1,839		)	951,546		(18,610		)
	ABS		3,366		(28		)	656		—			4,022		(28		)
	RMBS		46,493		(857		)	171,326		(6,769		)	217,819		(7,626		)
	CMBS		205,545		(7,529		)	38,587		(465		)	244,132		(7,994		)
	CLOs		13,278		(73		)	34,760		(129		)	48,038		(202		)
	Equity securities		568		(15		)	137		(9		)	705		(24		)
	Total investment portfolio		$	2,370,345	$	(50,915	)	$	294,916	$	(9,718	)	$	2,665,261	$	(60,633	)

For those securities in an unrealized loss position, the length of time the securities were in such a position, is measured by their month-end fair values. The unrealized losses in all categories of our investments as of December 31, 2017 and 2016 were primarily caused by changes in interest rates between the time of purchase and the respective year end. There were 586 and 607 securities in an unrealized loss position as of December 31, 2017 and 2016, respectively. As of December 31, 2017, the fair value as a percent of amortized cost of the securities in an unrealized loss position was 99% and approximately 27% of the securities in an unrealized loss position were backed by the U.S. Government.

The source of net investment income is shown in Table 5.4 below.



	Table	5.4
Investment income by source	(In thousands)		2017			2016			2015
Investment income by source	Fixed income		$	122,105		$	112,513		$	105,882
	Equity securities		206			182			208
	Cash equivalents		1,447			754			191
	Other		620			433			455
	Investment income		124,378			113,882			106,736
	Investment expenses		(3,507		)	(3,216		)	(2,995		)
	Net investment income		$	120,871		$	110,666		$	103,741

For the years ended December 31, 2017, 2016, and 2015, there were no OTTI losses in earnings.

The net realized investment gains (table 5.5) and the change in unrealized gains (losses) of investments (table 5.6) are shown below.



	Table	5.5
Net realized investment gains	(In thousands)		2017		2016		2015
Net realized investment gains	Fixed income		$	228	$	5,310	$	28,335
	Equity securities		21		3,622		26
	Other		—		—		—
	Total net realized investment gains		$	249	$	8,932	$	28,361



	Table	5.6
Change in unrealized gains (losses)	(In thousands)		2017			2016			2015
	Fixed income		$	69,026		$	(5,403	)	$	(33,687	)
	Equity securities		39			(36		)	(32		)
	Other		(13		)	14			1
	Total increase (decrease) in unrealized gains/losses		$	69,052		$	(5,425	)	$	(33,718	)

Gross realized gains and losses on investments are shown in Table 5.7 below.



	Table	5.7
Gross realized investment gains	(In thousands)		2017			2016			2015
Gross realized investment gains	Gross realized gains		$	1,599		$	11,909		$	30,039
	Gross realized losses		(1,350		)	(2,977		)	(1,678		)
	Net realized gains on securities		$	249		$	8,932		$	28,361

Fair Value Measurements

12 Months Ended

Dec. 31, 2017

Fair Value Disclosures [Abstract]

Fair Value Measurements

Recurring fair value measurements

Assets measured at fair value included those listed, by hierarchy level, in the following tables as of December 31, 2017 and 2016:



	Table	6.1a
Fair value hierarchy - current year	December 31, 2017
Fair value hierarchy - current year	(In thousands)		Fair Value		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
	U.S. Treasury securities and obligations of U.S. government corporations and agencies		$	178,846	$	81,598	$	97,248	$	—
	Obligations of U.S. states and political subdivisions		2,152,524		—		2,152,253		271
	Corporate debt securities		2,066,838		—		2,066,838		—
	ABS		4,923		—		4,923		—
	RMBS		181,849		—		181,849		—
	CMBS		297,312		—		297,312		—
	CLOs		101,023		—		101,023		—
	Total debt securities		4,983,315		81,598		4,901,446		271
	Equity securities ⁽¹⁾		7,246		2,978		—		4,268
	Total investments		$	4,990,561	$	84,576	$	4,901,446	$	4,539
	Real estate acquired ⁽²⁾		$	12,713	$	—	$	—	$	12,713



	Table	6.1b
Fair value hierarchy - prior year	December 31, 2016
Fair value hierarchy - prior year	(In thousands)		Fair Value		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
	U.S. Treasury securities and obligations of U.S. government corporations and agencies		$	73,530	$	30,690	$	42,840	$	—
	Obligations of U.S. states and political subdivisions		2,143,016		—		2,142,325		691
	Corporate debt securities		1,743,910		—		1,743,910		—
	ABS		59,565		—		59,565		—
	RMBS		224,209		—		224,209		—
	CMBS		319,817		—		319,817		—
	CLOs		121,175		—		121,175		—
	Total debt securities		4,685,222		30,690		4,653,841		691
	Equity securities ⁽¹⁾		7,128		2,860		—		4,268
	Total investments		$	4,692,350	$	33,550	$	4,653,841	$	4,959
	Real estate acquired ⁽²⁾		$	11,748	$	—	$	—	$	11,748


⁽¹⁾	Equity securities in Level 3 are carried at cost, which approximates fair value.


⁽²⁾	Real estate acquired through claim settlement, which is held for sale, is reported in other assets on the consolidated balance sheets.

Reconciliations of Level 3 assets

For assets and liabilities measured at fair value using significant unobservable inputs (Level 3), a reconciliation of the beginning and ending balances for the years ended December 31, 2017, 2016, and 2015 is shown in the following tables. There were no transfers into or out of Level 3 in those years and there we no losses included in earnings for those years attributable to the change in unrealized losses on assets still held at the end of each applicable year.



	Table	6.2a
Development of assets and liabilities classified within level 3 - current year	(In thousands)		Debt Securities			Equity Securities		Total Investments			Real Estate Acquired
	Balance at December 31, 2016		$	691		$	4,268	$	4,959		$	11,748
	Total realized/unrealized gains (losses):
	Included in earnings and reported as losses incurred, net		—			—		—			(1,315		)
	Purchases		—			—		—			34,749
	Sales		(420		)	—		(420		)	(32,469		)
	Balance at December 31, 2017		$	271		$	4,268	$	4,539		$	12,713



	Table	6.2b
Development of assets and liabilities classified within level 3 - prior year	(In thousands)		Debt Securities			Equity Securities			Total Investments			Real Estate Acquired
	Balance at December 31, 2015		$	1,228		$	2,855		$	4,083		$	12,149
	Total realized/unrealized gains (losses):
	Included in earnings and reported as net realized investment gains		—			3,579			3,579			—
	Included in earnings and reported as losses incurred, net		—			—			—			(1,142		)
	Purchases		—			4,258			4,258			36,859
	Sales		(537		)	(6,424		)	(6,961		)	(36,118		)
	Balance at December 31, 2016		$	691		$	4,268		$	4,959		$	11,748



	Table	6.2c
Development of assets and liabilities classified within level 3 - two years prior	(In thousands)		Debt Securities			Equity Securities		Total Investments			Real Estate Acquired
	Balance at December 31, 2014		$	1,846		$	321	$	2,167		$	12,658
	Total realized/unrealized gains (losses):
	Included in earnings and reported as losses incurred, net		—			—		—			(2,322		)
	Purchases		7			2,534		2,541			34,624
	Sales		(625		)	—		(625		)	(32,811		)
	Balance at December 31, 2015		$	1,228		$	2,855	$	4,083		$	12,149

Level 3 securities within total investments consisted primarily of equity securities that can only be redeemed or sold at their par value and only to the security issuer.

Authoritative guidance over disclosures about the fair value of financial instruments requires additional disclosure for financial instruments not measured at fair value. Certain financial instruments, including insurance contracts, are excluded from these fair value disclosure requirements. The carrying values of cash and cash equivalents (Level 1) and accrued investment income (Level 2) approximated their fair values. Additional fair value disclosures related to our investment portfolio are included in Note 5 – “Investments.”

Financial liabilities not measured at fair value

Financial liabilities are incurred in the normal course of our business. Table 6.3 compares the carrying value and fair value of our financial liabilities disclosed, but not carried, at fair value as of December 31, 2017 and 2016.



	Table	6.3
Fair value measurements - liabilities			December 31, 2017				December 31, 2016
	(In thousands)		Carrying Value		Fair Value		Carrying Value		Fair Value
	FHLB Advance		$	155,000	$	152,124	$	155,000	$	151,905
	5% Notes		—		—		144,789		147,679
	2% Notes		—		—		204,672		308,605
	5.75% Notes		418,560		465,473		417,406		445,987
	9% Debentures		256,872		353,507		256,872		323,040
	Total financial liabilities		$	830,432	$	971,104	$	1,178,739	$	1,377,216

The fair values of our 5% Notes, 2% Notes, 5.75% Notes, and 9% Debentures were based on observable market prices and the fair value of the FHLB Advance was estimated using discounted cash flows on current incremental borrowing rates for similar borrowing arrangements, and in all cases they are categorized as Level 2. See Note 7 - "Debt" for a description of the financial liabilities in table 6.3.

The 5.75% Notes and 9% Debentures are obligations of our holding company, MGIC Investment Corporation, and not of its subsidiaries.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Debt

12 Months Ended

Dec. 31, 2017

Debt Disclosure [Abstract]

Debt

Debt obligations

Table 7.1 shows the par value of our long-term debt obligations and their aggregate carrying values as of December 31, 2017 and 2016.



	Table	7.1
Long-term debt obligations			December 31,
	(In millions)		2017			2016
	FHLB Advance		$	155.0		$	155.0
	5% Notes		—			145.0
	2% Notes		—			207.6
	5.75% Notes		425.0			425.0
	9% Debentures		256.9			256.9
	Long-term debt, par value		836.9			1,189.5
	Debt issuance costs		(6.5		)	(10.8		)
	Long-term debt, carrying value		$	830.4		$	1,178.7

Table 7.2 shows the interest payments, on a consolidated basis, for our debt obligations outstanding during 2017 and 2016.



	Table	7.2
Interest payments on debt obligations			Years Ended December 31,
	(In millions)		2017		2016
	Revolving credit facility		$	0.9	$	—
	FHLB Advance		3.0		2.4
	5% Notes		3.6		10.6
	2% Notes		2.1		9.1
	5.75% Notes		25.1		—
	9% Debentures		23.1		27.4
	Total interest payments		$	57.8	$	49.5

2% Notes

On March 21, 2017, we issued an irrevocable notice of redemption in respect of our outstanding 2% Convertible Senior Notes due April 1, 2020 ("2% Notes"), with a redemption date of April 21, 2017. In April, holders of approximately $202.5 million of the outstanding principal exercised their rights to convert their notes to shares of our common stock. The remaining $5.1 million of outstanding principal was redeemed for cash. The conversions of the 2% Notes at a rate of 143.8332 shares per $1,000 principal amount resulted in the issuance of approximately 29.1 million shares of our common stock in April 2017. The conversions and cash redemption eliminated our debt obligation. A loss on debt extinguishment of $0.07 million was recognized on notes redeemed for cash. No gain or loss was recognized from the conversions as the outstanding debt issuance costs associated with the conversions were included in the carrying value of the notes, which was credited to shareholders' equity at the time of conversion.

In the third quarter of 2016, we entered into privately negotiated agreements to repurchase $292.4 million in aggregate principal of our outstanding 2% Notes at a purchase price of $362.1 million, plus accrued interest. We funded the purchases with $230.7 million in cash, using proceeds from the issuance of our 5.75% Notes, and by issuing to certain sellers approximately 18.3 million shares of our common stock. The excess of the purchase price over carrying value is reflected as a loss on debt extinguishment of $74.3 million on our consolidated statement of operations for the year ended December 31, 2016. The shares issued as consideration for the notes repurchases were repurchased as of December 31, 2016 using cash from our 5.75% Notes issuance. The repurchases of the 2% Notes reduced potentially dilutive shares by approximately 42.1 million shares, without considering the shares issued as partial consideration in the purchases of the 2% Notes or the repurchase of shares to offset such shares issued.

Interest on the 2% Notes was payable semi-annually in arrears on April 1 and October 1 of each year. Debt issuance costs were being amortized to interest expense over the contractual life of the notes.

Credit Facility

On March 21, 2017, we entered into a Credit Agreement with various lenders which provides for a $175 million unsecured revolving credit facility maturing on March 21, 2020. Revolving credit borrowings bear interest at a floating rate, which will be, at our option, either a eurocurrency rate or a base rate, in each case plus an applicable margin. The applicable margin is subject to adjustment based on our senior unsecured long-term debt rating, or if we do not have such a rating, our corporate or issuer rating. Amounts under the facility may be borrowed, repaid and reborrowed from time to time until the maturity of the revolving credit facility. Voluntary prepayments and commitment reductions are permitted at any time without fee subject to a minimum dollar requirement and, for outstanding eurocurrency loans, customary breakage costs.

We are required under the Credit Agreement to pay commitment fees on the average daily amount of the unused revolving commitments of the lenders, and an annual administrative fee to the administrative agent. The Credit Agreement contains affirmative, negative and financial covenants which are customary for financings of this type, including, among other things, limits on the creation of liens, limits on the incurrence of indebtedness, restrictions on dispositions, maximum debt-to-capital ratio, minimum consolidated stockholders' equity, minimum policyholder's position of MGIC, and compliance with the financial requirements of the PMIERs. The Credit Agreement includes customary events of default for facilities of this type (with customary grace periods, as applicable) and provides that, upon the occurrence of an event of default, payments of all outstanding loans may be accelerated and/or the lenders' commitments may be terminated. Upon the occurrence of certain insolvency or bankruptcy related events of default, all amounts payable under the Credit Agreement shall automatically become immediately due and payable, and the lenders' commitments will automatically terminate. In addition, upon the occurrence of certain insolvency or bankruptcy related events of default, or the failure to pay interest, principal or fees, the interest rates on all outstanding obligations will be increased.

In March 2017, we borrowed $150 million under the revolving credit facility, to fund a portion of the redemption price of the 2% Notes if holders did not elect to convert their 2% Notes. In April, we repaid the amount borrowed under the revolving credit facility because most holders elected to convert their notes. Costs incurred to enter into the Credit Agreement have been deferred and recorded as Other assets and will be amortized over the term of the Credit Agreement.

5% Notes

On May 1, 2017, our 5% Notes due in 2017 ("5% Notes") matured and we repaid the outstanding $145 million in aggregate par value, plus accrued interest with cash at our holding company. Interest on the 5% Notes was payable semi-annually in arrears on May 1 and November 1 of each year.

In 2016, we repurchased $188.5 million in aggregate principal of our 5% Notes at a purchase price of $195.5 million, plus accrued interest using funds held at our holding company. The excess of the purchase price over carrying value was reflected as a loss on debt extinguishment of $7.9 million on our consolidated statement of operations. Our 2016 5% Notes repurchases reduced our potentially dilutive shares by approximately 14.0 million shares.

5.75% Notes

In August 2016, we issued $425 million aggregate principal amount of 5.75% Senior Notes due in 2023 ("5.75% Notes") and received net proceeds, after the deduction of underwriting fees, of $418.1 million. Interest on the 5.75% Notes is payable semi-annually on February 15 and August 15 of each year, commencing on February 15, 2017. We have the option to redeem these notes, in whole or in part, at any time or from time to time prior to maturity at a redemption price equal to the greater of (i)100% of the aggregate principal amount of the notes to be redeemed and (ii) the make-whole amount, which is the sum of the present values of the remaining scheduled payments of principal and interest discounted at the treasury rate defined in the notes plus 50 basis points, plus, in each case, accrued interest thereon to, but excluding, the redemption date. In addition to underwriting fees, we incurred approximately $1.2 million of other expenses associated with the issuance of these notes.

The 5.75% Notes have covenants customary for securities of this nature, including customary events of default, and further provide that the trustee or holders of at least 25% in aggregate principal amount of the outstanding 5.75% Notes may declare them immediately due and payable upon the occurrence of certain events of default after the expiration of the applicable grace period. In addition, in the case of an event of default arising from certain events of bankruptcy, insolvency or reorganization relating to the Company or any of its significant subsidiaries, the 5.75% Notes will become due and payable immediately. This description is not intended to be complete in all respects and is qualified in its entirety by the terms of the 5.75% Notes, including their covenants and events of default. We were in compliance with all covenants as of December 31, 2017.

The net proceeds from the 5.75% Notes issuance were primarily used as (i) cash consideration to repurchase a portion of our 2% Notes, and (ii) to repurchase the shares issued as partial consideration in the repurchases of our 2% Notes, as described above. The remaining proceeds are being held for general corporate purposes.

FHLB Advance

In February 2016, MGIC borrowed $155.0 million in the form of a fixed rate advance from the Federal Home Loan Bank of Chicago ("FHLB Advance"). Interest on the Advance is payable monthly at an annual rate, fixed for the term of the Advance, of 1.91%. The principal of the Advance matures on February 10, 2023. MGIC may prepay the Advance at any time. Such prepayment would be below par if interest rates have risen after the Advance was originated, or above par if interest rates have declined. The Advance is secured by eligible collateral whose market value must be maintained at 102% of the principal balance of the Advance. MGIC provided eligible collateral from its investment portfolio.

9% Debentures

As of December 31, 2017 and 2016 we had outstanding $256.9 million principal amount of our 9% Debentures due in 2063 ("9% Debentures"). In February 2016, MGIC purchased $132.7 million in aggregate principal of our outstanding 9% Debentures at a purchase price of $150.7 million, plus accrued interest. The 9% Debentures include a conversion feature that allows us, at our option, to make a cash payment to converting holders in lieu of issuing shares of common stock upon conversion of the 9% Debentures. The accounting standards applicable to extinguishment of debt with a cash conversion feature require the consideration paid to be allocated between the extinguishment of the liability component and reacquisition of the equity component. The purchase of the 9% Debentures resulted in an $8.3 million loss on debt extinguishment on the consolidated statement of operations for the year ended December 31, 2016, which represents the difference between the fair value and the carrying value of the liability component on the purchase date. In addition, our shareholders’ equity was separately reduced by $6.3 million related to the reacquisition of the equity component. For GAAP accounting purposes, the 9% Debentures owned by MGIC are considered retired and are eliminated in our consolidated financial statements and the underlying common stock equivalents, approximately 9.8 million shares, are not included in the computation of diluted shares.

The 9% Debentures are currently convertible, at the holder's option, at an initial conversion rate, which is subject to adjustment, of 74.0741 common shares per $1,000 principal amount of the 9% Debentures at any time prior to the maturity date. This represents an initial conversion price of approximately $13.50 per share. If a holder elects to convert their 9% Debentures, deferred interest, if any, owed on the 9% Debentures being converted is also converted into shares of our common stock. The conversion rate for any deferred interest is based on the average price that our shares traded at during a 5-day period immediately prior to the election to convert. We have 19.0 million authorized shares reserved for conversion under our 9% debentures.

We may redeem the 9% Debentures in whole or in part from time to time, at our option, at a redemption price equal to 100% of the principal amount of the 9% Debentures being redeemed, plus any accrued and unpaid interest, if the closing sale price of our common stock exceeds $17.55 for at least 20 of the 30 trading days preceding notice of the redemption.

Interest on the 9% Debentures is payable semi-annually in arrears on April 1 and October 1 of each year. As long as no event of default with respect to the debentures has occurred and is continuing, we may defer interest, under an optional deferral provision, for one or more consecutive interest periods up to 10 years without giving rise to an event of default. Deferred interest will accrue additional interest at the rate then applicable to the debentures. During an optional deferral period we may not pay or declare dividends on our common stock.

When interest on the 9% Debentures is deferred, we are required, not later than a specified time, to use reasonable commercial efforts to begin selling qualifying securities to persons who are not our affiliates. The specified time is one business day after we pay interest on the 9% Debentures that was not deferred, or if earlier, the fifth anniversary of the scheduled interest payment date on which the deferral started. Qualifying securities are common stock, certain warrants and certain non-cumulative perpetual preferred stock. The requirement to use such efforts to sell such securities is called the Alternative Payment Mechanism.

The net proceeds of Alternative Payment Mechanism sales are to be applied to the payment of deferred interest, including the compound portion. We cannot pay deferred interest other than from the net proceeds of Alternative Payment Mechanism sales, except at the final maturity of the debentures or at the tenth anniversary of the start of the interest deferral. The Alternative Payment Mechanism does not require us to sell common stock or warrants before the fifth anniversary of the interest payment date on which that deferral started if the net proceeds (counting any net proceeds of those securities previously sold under the Alternative Payment Mechanism) would exceed the 2% cap. The 2% cap is 2% of the average closing price of our common stock times the number of our outstanding shares of common stock. The average price is determined over a specified period ending before the issuance of the common stock or warrants being sold, and the number of outstanding shares is determined as of the date of our most recent publicly released financial statements.

We are not required to issue under the Alternative Payment Mechanism a total of more than 10 million shares of common stock, including shares underlying qualifying warrants. In addition, we may not issue under the Alternative Payment Mechanism qualifying preferred stock if the total net proceeds of all issuances would exceed 25% of the aggregate principal amount of the debentures.

The Alternative Payment Mechanism does not apply during any period between scheduled interest payment dates if there is a “market disruption event” that occurs over a specified portion of such period. Market disruption events include any material adverse change in domestic or international economic or financial conditions.

The provisions of the 9% Debentures are complex. The description above is not intended to be complete in all respects. Moreover, that description is qualified in its entirety by the terms of the 9% Debentures, including their covenants and events of default. We were in compliance with all covenants at December 31, 2017. The 9% Debentures rank junior to all of our existing and future senior indebtedness.

Loss Reserves

12 Months Ended

Dec. 31, 2017

Insurance Loss Reserves [Abstract]

Loss Reserves

As described in Note 3 – “Summary of Significant Accounting Policies – Loss Reserves,” we establish reserves to recognize the estimated liability for losses and LAE related to defaults on insured mortgage loans. Loss reserves are established by estimating the number of loans in our inventory of delinquent loans that will result in a claim payment, which is referred to as the claim rate, and further estimating the amount of the claim payment, which is referred to as claim severity.

Estimation of losses is inherently judgmental. The conditions that affect the claim rate and claim severity include the current and future state of the domestic economy, including unemployment and the current and future strength of local housing markets; exposure on insured loans; the amount of time between default and claim filing; and curtailments and rescissions. The actual amount of the claim payments may be substantially different than our loss reserve estimates. Our estimates could be adversely affected by several factors, including a deterioration of regional or national economic conditions, including unemployment, leading to a reduction in borrowers’ income and thus their ability to make mortgage payments, and a drop in housing values which may affect borrower willingness to continue to make mortgage payments when the value of the home is below the mortgage balance. Changes to our estimates could result in a material impact to our consolidated results of operations and financial position, even in a stable economic environment.

The “Losses incurred” section of table 8.1 below shows losses incurred on delinquencies that occurred in the current year and in prior years. The amount of losses incurred relating to delinquencies that occurred in the current year represents the estimated amount to be ultimately paid on such delinquencies. The amount of losses incurred relating to delinquencies that occurred in prior years represents the difference between the actual claim rate and severity associated with those delinquencies resolved in the current year compared to the estimated claim rate and severity at the prior year-end, as well as a re-estimation of amounts to be ultimately paid on delinquencies continuing from the end of the prior year. This re-estimation of the claim rate and severity is the result of our review of current trends in the delinquent inventory, such as percentages of defaults that have resulted in a claim, the amount of the claims relative to the average loan exposure, changes in the relative level of delinquencies by geography and changes in average loan exposure.

Losses incurred on delinquencies that occurred in the current year decreased in 2017 compared to 2016 due to a decrease in the estimated claim rate on recently reported delinquencies, and in 2016 compared to 2015, primarily due to a decrease in the number of new delinquencies, net of cures, as well as a decrease in the estimated claim rate on recently reported delinquencies.

See "Hurricane activity" below for additional information on new notice activity and items in our delinquent inventory from the hurricane impacted areas. Based on our analysis and past experience, new notices received in areas impacted by hurricanes generally cure at a higher rate than notices received in the normal course of business and we have estimated a materially lower claim rate on the estimated new notices caused by the hurricane activity; however, our estimated severity was similar to other new notices received.

The “Losses paid” section of table 8.1 below shows the amount of losses paid on delinquent notices received in the current year and losses paid on delinquent notices received in prior years. For several years, the average time it took to receive a claim associated with a delinquency had increased significantly from our historical experience of approximately twelve months. This was, in part, due to new loss mitigation protocols established by servicers and to changes in some state foreclosure laws that may include, for example, a requirement for additional review and/or mediation processes. In recent quarters, we have experienced a decline in the average time servicers are utilizing to process foreclosures, which has reduced the average time to receive a claim associated with new delinquent notices that do not cure. All else being equal, the longer the period between delinquency and claim filing, the greater the severity.

Our estimate of premiums to be refunded on expected claim payments is accrued for separately in "Other liabilities" on our consolidated balance sheets and approximated $61 million and $85 million at December 31, 2017 and 2016, respectively.

During 2017 and 2016, our losses paid included amounts paid upon commutation of coverage on pools of non-performing loans ("NPLs"), and in 2016 our losses paid also included amounts paid in connection with settlements for disputes concerning our claims paying practices. Losses paid in 2015 included amounts paid in connection with settlements for disputes concerning our claims paying practices. The impacts of the commutations of coverage on NPLs and/or settlements in each of the past three years were as follows:


•	2017 - 1,337 notices removed from default inventory with an amount paid of $54 million,


•	2016 - 1,273 notices removed from default inventory with an amount paid of $53 million,


•	2015 - 1,121 notices removed from default inventory with an amount paid of $10 million.

In each of 2016 and 2015, we paid $42 million in connection with a 2012 settlement agreement with Freddie Mac regarding the aggregate loss limit under certain pool insurance policies. The final payment under that settlement agreement was made on December 1, 2016.

Table 8.1 provides a reconciliation of beginning and ending loss reserves for each of the past three years:



	Table	8.1
Development of reserves for losses and loss adjustment expenses	(In thousands)		2017			2016			2015
	Reserve at beginning of year		$	1,438,813		$	1,893,402		$	2,396,807
	Less reinsurance recoverable		50,493			44,487			57,841
	Net reserve at beginning of year		1,388,320			1,848,915			2,338,966

	Losses incurred:
	Losses and LAE incurred in respect of delinquent notices received in:
	Current year		284,913			387,815			453,849
	Prior years ⁽¹⁾		(231,204		)	(147,658		)	(110,302		)
	Total losses incurred		53,709			240,157			343,547

	Losses paid:
	Losses and LAE paid in respect of delinquent notices received in:
	Current year		11,267			14,823			25,980
	Prior years		493,300			689,258			823,058
	Reinsurance terminations ⁽²⁾		301			(3,329		)	(15,440		)
	Total losses paid		504,868			700,752			833,598
	Net reserve at end of year		937,161			1,388,320			1,848,915
	Plus reinsurance recoverables		48,474			50,493			44,487
	Reserve at end of year		$	985,635		$	1,438,813		$	1,893,402


⁽¹⁾	A negative number for prior year losses incurred indicates a redundancy of prior year loss reserves. See table 8.2 below for more information about prior year loss development.

⁽²⁾

In a termination, the reinsurance agreement is cancelled, with no future premium ceded and amounts for any incurred but unpaid losses paid to us. Amounts paid to (received from) reinsurers result in an increase (decrease) in net losses paid. The change in net losses paid on our losses incurred is offset by a corresponding change in the reinsurance recoverable, resulting in no net impact on losses incurred. (See Note 9 – “Reinsurance”).

Table 8.2 below shows the development of reserves in 2017, 2016 and 2015 for previously received delinquencies.



	Table	8.2
Reserve development on previously received delinquencies	(In millions)		2017			2016			2015
	Decrease in estimated claim rate on primary delinquencies		$	(248	)	$	(148	)	$	(141	)
	Increase in estimated severity on primary delinquencies		9			9			43
	Change in estimates related to pool reserves, LAE reserves, reinsurance and other		8			(9		)	(12		)
	Total prior year loss development ⁽¹⁾		$	(231	)	$	(148	)	$	(110	)


⁽¹⁾	A negative number for prior year loss development indicates a redundancy of prior year loss reserves.

For the years ended December 31, 2017, 2016 and 2015, we experienced favorable development on previously received delinquencies. This development was, in part, due to the resolution of approximately 67%, 63% and 60% for the years ended December 31, 2017, 2016 and 2015, respectively, of the prior year delinquent inventory, with improved cure rates. During 2017, cure activity on loans that were delinquent twelve months or more was significantly higher than our previous estimates. During 2015, the claim rate development was also favorably impacted by re-estimations of previously recorded reserves relating to disputes on our claims paying practices and adjustments to IBNR. The favorable development for the years ended 2017, 2016, and 2015 was offset, in part, by an increase in the estimated severity on previously reported delinquencies remaining in the delinquent inventory.

Delinquent Inventory

A rollforward of our primary delinquent inventory for the years ended December 31, 2017, 2016, and 2015 appears in table 8.3 below. The information concerning new notices and cures is compiled from monthly reports received from loan servicers. The level of new notice and cure activity reported in a particular month can be influenced by, among other things, the date on which a servicer generates its report, the number of business days in a month and transfers of servicing between loan servicers.



	Table	8.3
Delinquent inventory rollforward			2017		2016		2015
	Delinquent inventory at beginning of year		50,282		62,633		79,901
	New Notices		68,268		67,434		74,315
	Cures		(61,094	)	(65,516	)	(73,610	)
	Paids (including those charged to a deductible or captive)		(9,206	)	(12,367	)	(16,004	)
	Rescissions and denials		(357	)	(629	)	(848	)
	Other items removed from inventory		(1,337	)	(1,273	)	(1,121	)
	Delinquent inventory at end of year		46,556		50,282		62,633

2017 delinquent inventory

Hurricane activity

New default notice activity increased in 2017 compared to the prior year (particularly in the fourth quarter) because of hurricane activity that primarily impacted Puerto Rico, Texas, and Florida in the third quarter of 2017. In response to the hurricanes, the Federal Emergency Management Agency has declared Individual Assistance Disaster Areas ("IADA") which we are utilizing to identify new notices of delinquency for reserving and loss mitigation purposes. We received 9,294 new notices of delinquency on loans in the IADAs in the fourth quarter of 2017, which compares to 1,968 new notices in the same areas in the fourth quarter of 2016. Loans in our ending delinquent inventory within the IADAs were 12,446 and 7,162 as of December 31, 2017 and 2016, respectively.

The new notice activity from hurricane impacted areas in the fourth quarter of 2017 has increased the percentage of our delinquent inventory that has been delinquent for three months or less (table 8.4) and correspondingly our percentage of delinquent inventory with three payments or less (table 8.5) delinquent has also increased.

2016 and 2015 delinquent inventory

The decrease in the primary delinquent inventory experienced during 2016 and 2015 from the respective prior year was generally across all markets and all book years prior to 2013. In 2016 and 2015, the percentage of loans in the inventory that had been delinquent for 12 or more consecutive months had decreased compared to the respective prior year.

Historically as a delinquency ages it becomes more likely to result in a claim. The percentage of loans that have been delinquent for 12 or more consecutive months and the number of loans in our primary claims received inventory have been affected by our suspended rescissions and the resolution of certain of those rescissions discussed below and in Note 17 - "Litigation and Contingencies".

The number of consecutive months that a borrower has been delinquent is shown in the table below.



	Table	8.4
Delinquent inventory - consecutive months delinquent			December 31,
			2017			2016			2015
	3 months or less		17,119	37	%	12,194	24	%	13,053	21	%
	4 - 11 months		12,050	26	%	13,450	27	%	15,763	25	%
	12 months or more⁽¹⁾		17,387	37	%	24,638	49	%	33,817	54	%
	Total primary delinquent inventory		46,556	100	%	50,282	100	%	62,633	100	%

	Primary claims received inventory included in ending delinquent inventory		954	2	%	1,385	3	%	2,769	4	%


⁽¹⁾	Approximately 45%, 47% and 50% of the primary delinquent inventory delinquent for 12 consecutive months or more has been delinquent for at least 36 consecutive months as of December 31, 2017, 2016 and 2015, respectively.

The length of time a loan is in the delinquent inventory can differ from the number of payments that the borrower has not made or is considered delinquent. These differences typically result from a borrower making monthly payments that do not result in the loan becoming fully current. The number of payments that a borrower is delinquent is shown in table 8.5 below.



	Table	8.5
Delinquent inventory - number of payments delinquent			December 31,
			2017			2016			2015
	3 payments or less		21,678	46	%	18,419	36	%	20,360	33	%
	4 - 11 payments		12,446	27	%	12,892	26	%	15,092	24	%
	12 payments or more		12,432	27	%	18,971	38	%	27,181	43	%
	Total primary delinquent inventory		46,556	100	%	50,282	100	%	62,633	100	%

Pool insurance default inventory decreased to 1,309 at December 31, 2017 from 1,883 at December 31, 2016 and 2,739 at December 31, 2015.

Claims paying practices

Our loss reserving methodology incorporates our estimates of future rescissions. A variance between ultimate actual rescission rates and our estimates, as a result of the outcome of litigation, settlements or other factors, could materially affect our losses. Our estimate of premiums to be refunded on expected future rescissions is accrued for separately and is included in "Other liabilities" on our consolidated balance sheets.

For information about discussions and legal proceedings with customers with respect to our claims paying practices, including settlements that we believe are probable, as defined in ASC 450-20, see Note 17 – “Litigation and Contingencies.”

Reinsurance

12 Months Ended

Dec. 31, 2017

Reinsurance Disclosures [Abstract]

Reinsurance

Our consolidated financial statements reflect the effects of assumed and ceded reinsurance transactions. Assumed reinsurance refers to the acceptance of certain insurance risks that other insurance companies have underwritten. Ceded reinsurance involves transferring certain insurance risks (along with the related earned premiums) we have underwritten to other insurance companies who agree to share these risks. The purpose of ceded reinsurance is to protect us, at a cost, against a fixed percentage of losses arising from our mortgage guaranty policies covered by the agreement and to manage our capital requirements under PMIERs. Reinsurance is currently placed on a quota-share basis, but we also have captive reinsurance agreements that remain in effect. The reinsurance agreements we have entered into are discussed below.

Table 9.1 below shows the effect of all reinsurance agreements on premiums earned and losses incurred as reflected in the consolidated statements of operations.



	Table	9.1
Reinsurance			Years ended December 31,
	(In thousands)		2017			2016			2015
	Premiums earned:
	Direct		$	1,059,973		$	1,058,545		$	997,892
	Assumed		509			662			1,178
	Ceded		(125,735		)	(133,981		)	(102,848		)
	Net premiums earned		$	934,747		$	925,226		$	896,222

	Losses incurred:
	Direct		$	74,727		$	273,207		$	369,680
	Assumed		183			1,138			1,552
	Ceded		(21,201		)	(34,188		)	(27,685		)
	Net losses incurred		$	53,709		$	240,157		$	343,547

Quota share reinsurance

Each of the reinsurers under our 2017 and 2015 quota share reinsurance agreements ("2017 QSR Transaction" and "2015 QSR Transaction", respectively) and proposed 2018 quota share reinsurance agreement ("2018 QSR Transaction") has an insurer financial strength rating of A- or better by Standard and Poor's Rating Services, A.M. Best, or both.

2017 QSR Transaction. Effective January 1, 2017, this transaction provides coverage on new business written from the effective date through December 29, 2017 that meets certain eligibility requirements. The agreement cedes losses incurred and premiums on or after the effective date through December 31, 2028 at which time the agreement expires. Early termination of the agreement can be elected by us effective December 31, 2021 for a fee, or under specified scenarios for no fee upon prior written notice, including if we will receive less than 90% of the full credit amount under the PMIERs for the risk ceded in any required calculation period.

2015 QSR Transaction. Effective July 1, 2015, this transaction provides coverage on policies that were in the 2013 quota share reinsurance agreement ("2013 QSR Transaction"); additional qualifying in force policies as of the agreement effective date which either had no history of defaults, or where a single default had been cured for twelve or more months at the agreement effective date; and all qualifying new insurance written through December 31, 2016. Compared to the 2013 QSR Transaction, the 2015 QSR Transaction increased the amount of our IIF covered by reinsurance and the amount of premiums and losses that will be ceded. The agreement cedes losses incurred and premiums on or after the effective date through December 31, 2024, at which time the agreement expires. Early termination of the agreement can be elected by us effective December 31, 2018 for a fee, or under specified scenarios for no fee upon prior written notice, including if we will receive less than 90% of the full credit amount under the PMIERs for the risk ceded in any required calculation period.

The structure of the 2017 and 2015 QSR Transactions are both 30% quota share agreements for all policies covered, with a 20% ceding commission as well as a profit commission. Generally, under each transaction, we will receive a profit commission provided that the loss ratio on the loans covered under the agreement remains below 60%, with higher levels of losses ceded reducing our profit commission.

2013 QSR Transaction. Effective July 1, 2015, we commuted and settled our 2013 QSR Transaction. The settlement included unearned premiums, loss reserves, and profit commission. The commutation resulted in an increase in net premiums written and earned of $69.4 million and $11.6 million, respectively, and a decrease in ceding commissions of $11.6 million in the third quarter of 2015. Receipt of our profit commission of $142.5 million, in addition to other premium and loss amounts, was also completed as part of the settlement.

2018 QSR Transaction. We have agreed to terms on a 2018 QSR Transaction with a group of unaffiliated reinsurers to manage our exposure to losses resulting from the covered mortgage guaranty insurance policies and to provide reinsurance capital credit under the PMIERs. The GSEs have approved the terms of our proposed 2018 QSR Transaction. The 2018 QSR Transaction is expected to be executed during the first quarter of 2018 with an effective date of January 1, 2018, and will provide coverage on new business written January 1, 2018 through December 31, 2018 that meets certain eligibility requirements. Under the agreed upon terms, the 2018 QSR Transaction will cede losses incurred and premiums on or after the effective date through December 31, 2029, at which time the agreement expires. Early termination of the agreement can be elected by us effective December 31, 2021, and annually thereafter, for a fee, or under specified scenarios for no fee upon prior written notice, including if we will receive less than 90% of the full credit amount under the PMIERs for the risk ceded in any required calculation period.

The agreed upon structure of the 2018 QSR Transaction is a 30% quota share for all policies covered, with a 20% ceding commission as well as a profit commission. Generally, under the 2018 QSR Transaction, we will receive a profit commission provided that the loss ratio on the loans covered under the agreement remains below 54%.

Table 9.2 provides a summary of our quota share reinsurance agreements, excluding captive agreements, for 2017, 2016 and 2015.



	Table	9.2
Quota share reinsurance			Years ended December 31,
Quota share reinsurance	(In thousands)		2017		2016		2015 ⁽³⁾
	Ceded premiums written, net of profit commission ⁽¹⁾		$	120,974	$	125,460	$	41,233
	Ceded premiums earned, net of profit commission ⁽¹⁾		120,974		125,460		88,587
	Ceded losses incurred		22,336		30,201		17,484
	Ceding commissions ⁽²⁾		49,321		47,629		30,816
	Profit commission		125,629		112,685		112,847


⁽¹⁾	Since July 1, 2015, premiums are ceded on an earned and received basis as defined in our QSR Transactions currently in effect.


⁽²⁾	Ceding commissions are reported within Other underwriting and operating expenses, net on the consolidated statements of operations.


⁽³⁾	The year ended December 31, 2015 includes the non-recurring impact of commuting our 2013 QSR Transaction (see "2013 QSR Transaction" above for additional information). The commutation had no impact on ceded losses incurred.

Under the terms of our QSR Transactions currently in effect, reinsurance premiums, ceding commission and profit commission are settled net on a quarterly basis. The reinsurance premium due after deducting the related ceding commission and profit commission is reported within "Other liabilities" on the consolidated balance sheets.

The reinsurance recoverable on loss reserves was $39.3 million as of December 31, 2017 and $31.8 million as of December 31, 2016. The reinsurance recoverable balance is secured by funds on deposit from the reinsurers which are based on the funding requirements of PMIERs that address ceded risk.

Captive reinsurance

In the past, MGIC also obtained captive reinsurance. In a captive reinsurance arrangement, the reinsurer is affiliated with the lender for whom MGIC provides mortgage insurance. As part of our settlement with the Consumer Financial Protection Bureau ("CFPB") in 2013 and with the Minnesota Department of Commerce in 2015, MGIC has agreed to not enter into any new captive reinsurance agreement or reinsure any new loans under any existing captive reinsurance agreement for a period of ten years subsequent to the respective settlements. In accordance with the CFPB settlement, all of our active captive arrangements were placed into run-off. In addition, the GSEs will not approve any future reinsurance or risk sharing transaction with a mortgage enterprise or an affiliate of a mortgage enterprise.

The reinsurance recoverable on loss reserves related to captive agreements was $9 million at December 31, 2017 which was supported by $80 million of trust assets, while at December 31, 2016 the reinsurance recoverable on loss reserves related to captive agreements was $19 million which was supported by $91 million of trust assets. Each captive reinsurer is required to maintain a separate trust account to support its combined reinsured risk on all annual books. MGIC is the sole beneficiary of the trusts.

Other Comprehensive Income (Loss)

12 Months Ended

Dec. 31, 2017

Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]

Other Comprehensive Income (Loss)

The pretax components of our other comprehensive income (loss) and related income tax (expense) benefit for the years ended December 31, 2017, 2016 and 2015 are included in table 10.1 below:



	Table	10.1
Components of other comprehensive income (loss)	(In thousands)		2017			2016			2015
	Net unrealized investment gains (losses) arising during the year		$	69,052		$	(5,425	)	$	(33,718	)
	Income tax (expense) benefit		(21,505		)	1,776			11,738
	Valuation allowance ⁽¹⁾		—			—			62,383
	Net of taxes		47,547			(3,649		)	40,403

	Net changes in benefit plan assets and obligations		(8,983		)	(14,799		)	(12,818		)
	Income tax benefit		3,144			5,179			4,487
	Valuation allowance ⁽¹⁾		—			—			(7,383		)
	Net of taxes		(5,839		)	(9,620		)	(15,714		)

	Net changes in unrealized foreign currency translation adjustment		45			(1,463		)	(5,699		)
	Income tax (expense) benefit		(14		)	512			2,000
	Valuation allowance ⁽¹⁾		—			—			(529		)
	Net of taxes		31			(951		)	(4,228		)

	Total other comprehensive income (loss)		60,114			(21,687		)	(52,235		)
	Total income tax (expense) benefit, net of valuation allowance		(18,375		)	7,467			72,696
	Total other comprehensive income (loss), net of tax		$	41,739		$	(14,220	)	$	20,461


⁽¹⁾	See Note 12 – “Income Taxes” for a discussion of the valuation allowance recorded against deferred tax assets in 2015.

The pretax and related income tax benefit (expense) components of the amounts reclassified from our accumulated other comprehensive loss ("AOCL") to our consolidated statements of operations for the years ended December 31, 2017, 2016 and 2015 are included in table 10.2 below:



	Table	10.2
Reclassifications from AOCL	(In thousands)		2017			2016			2015
	Reclassification adjustment for net realized (losses) gains included in net income ⁽¹⁾		$	(2,580	)	$	6,207		$	11,693
	Income tax benefit (expense)		903			(2,050		)	(4,076		)
	Valuation allowance ⁽²⁾		—			—			3,635
	Net of taxes		(1,677		)	4,157			11,252

	Reclassification adjustment related to benefit plan assets and obligations ⁽³⁾		906			1,480			2,184
	Income tax (expense)		(317		)	(518		)	(764		)
	Valuation allowance ⁽²⁾		—			—			574
	Net of taxes		589			962			1,994

	Reclassification adjustment related to foreign currency ⁽⁴⁾		—			1,467			—
	Income tax (expense)		—			(513		)	—
	Net of taxes		—			954			—

	Total reclassifications		(1,674		)	9,154			13,877
	Total income tax benefit (expense), net of valuation allowance		586			(3,081		)	(631		)
	Total reclassifications, net of tax		$	(1,088	)	$	6,073		$	13,246


⁽¹⁾	(Decreases) increases Net realized investment gains on the consolidated statements of operations.


⁽²⁾	See Note 12 – “Income Taxes” for a discussion of the valuation allowance recorded against deferred tax assets in 2015.


⁽³⁾	Decreases (increases) Other underwriting and operating expenses, net on the consolidated statements of operations.


⁽⁴⁾	Increases (decreases) Other revenue on the consolidated statements of operations.

A rollforward of AOCL for the years ended December 31, 2017, 2016, and 2015, including amounts reclassified from AOCL, is included in table 10.3 below.



	Table	10.3
Rollforward of AOCL	(In thousands)		Net unrealized gains and losses on available-for-sale securities			Net benefit plan assets and obligations recognized in shareholders' equity			Net unrealized foreign currency translation			Total AOCL
	Balance, December 31, 2014, net of tax		$	(57,551	)	$	(28,938	)	$	5,148		$	(81,341	)
	Other comprehensive income (loss) before reclassifications		51,655			(13,720		)	(4,228		)	33,707
	Less: Amounts reclassified from AOCL		11,252			1,994			—			13,246
	Balance, December 31, 2015, net of tax		(17,148		)	(44,652		)	920			(60,880		)
	Other comprehensive income (loss) before reclassifications		508			(8,658		)	3			(8,147		)
	Less: Amounts reclassified from AOCL		4,157			962			954			6,073
	Balance, December 31, 2016, net of tax		(20,797		)	(54,272		)	(31		)	(75,100		)
	Other comprehensive income (loss) before reclassifications		45,870			(5,250		)	31			40,651
	Less: Amounts reclassified from AOCL		(1,677		)	589			—			(1,088		)
	Less: Amounts reclassified for lower enacted corporate tax rate		(2,525		)	12,947			—			10,422
	Balance, December 31, 2017, net of tax		$	29,275		$	(73,058	)	$	—		(43,783		)

Benefit Plans

12 Months Ended

Dec. 31, 2017

Retirement Benefits [Abstract]

Benefit Plans

We have a non-contributory defined benefit pension plan covering substantially all domestic employees, as well as a supplemental executive retirement plan. We also offer both medical and dental benefits for retired domestic employees, their eligible spouses and dependents under a postretirement benefit plan. The following tables 11.1, 11.2, and 11.3 provide the components of aggregate annual net periodic benefit cost for each of the years ended December 31, 2017, 2016, and 2015 and changes in the benefit obligation and the funded status of the pension, supplemental executive retirement and other postretirement benefit plans as recognized in the consolidated balance sheets as of December 31, 2017 and 2016.



	Table	11.1
Components of net periodic benefit cost			Pension and Supplemental Executive Retirement Plans									Other Postretirement Benefits
Components of net periodic benefit cost	(in thousands)		12/31/2017			12/31/2016			12/31/2015			12/31/2017			12/31/2016			12/31/2015
	1. Company Service Cost		$	9,556		$	9,130		$	10,256		$	813		$	751		$	833
	2. Interest Cost		15,475			15,906			15,847			706			704			697
	3. Expected Return on Assets		(20,099		)	(19,508		)	(21,109		)	(5,248		)	(4,886		)	(4,991		)
	4. Other Adjustments		—			—			—			—			—			—
	Subtotal		4,932			5,528			4,994			(3,729		)	(3,431		)	(3,461		)
	5. Amortization of:
	a. Net Transition Obligation/(Asset)		—			—			—			—			—			—
	b. Net Prior Service Cost/(Credit)		(426		)	(687		)	(845		)	(6,649		)	(6,649		)	(6,649		)
	c. Net Losses/(Gains)		6,169			5,856			5,485			—			—			(175		)
	Total Amortization		5,743			5,169			4,640			(6,649		)	(6,649		)	(6,824		)
	6. Net Periodic Benefit Cost		10,675			10,697			9,634			(10,378		)	(10,080		)	(10,285		)
	7. Cost of settlements		—			1,277			3,172			—			—			—
	8. Total Expense for Year		$	10,675		$	11,974		$	12,806		$	(10,378	)	$	(10,080	)	$	(10,285	)



	Table	11.2
Development of funded status			Pension and Supplemental Executive Retirement Plans						Other Postretirement Benefits
	(in thousands)		12/31/2017			12/31/2016			12/31/2017			12/31/2016
	Actuarial Value of Benefit Obligations
	1. Measurement Date		12/31/2017			12/31/2016			12/31/2017			12/31/2016
	2. Accumulated Benefit Obligation		$	411,996		$	360,423		$	24,716		$	17,378

	Funded Status/Asset (Liability) on the Consolidated Balance Sheet
	1. Projected Benefit Obligation		$	(417,770	)	$	(369,808	)	$	(24,716	)	$	(17,378	)
	2. Plan Assets at Fair Value		401,142			360,900			85,303			70,408
	3. Funded Status - Overfunded/Asset		N/A			N/A			$	60,587		$	53,030
	4. Funded Status - Underfunded/Liability		(16,628		)	(8,908		)	N/A			N/A



	Table	11.3
Accumulated other comprehensive income (loss)			Pension and Supplemental Executive Retirement Plans						Other Postretirement Benefits
	(in thousands)		12/31/2017			12/31/2016			12/31/2017			12/31/2016
	1. Net Actuarial (Gain)/Loss		$	109,904		$	103,861		$	(10,234	)	$	(6,088	)
	2. Net Prior Service Cost/(Credit)		(1,850		)	(2,286		)	(5,342		)	(11,991		)
	3. Net Transition Obligation/(Asset)		—			—			—			—
	4. Total at Year End		$	108,054		$	101,575		$	(15,576	)	$	(18,079	)

The amortization of gains and losses resulting from actual experience different from assumed experience or changes in assumptions including discount rates is included as a component of Net Periodic Benefit Cost/(Income) for the year. The gain or loss in excess of a 10% corridor is amortized by the average remaining service period of participating employees expected to receive benefits under the plan.

Table 11.4 shows the changes in the projected benefit obligation for 2017 and 2016.



	Table	11.4
Change in projected benefit / accumulated benefit obligation			Pension and Supplemental Executive Retirement Plans						Other Postretirement Benefits
	(in thousands)		12/31/2017			12/31/2016			12/31/2017			12/31/2016
	1. Benefit Obligation at Beginning of Year		$	369,808		$	349,483		$	17,378		$	16,423
	2. Company Service Cost		9,556			9,130			813			751
	3. Interest Cost		15,475			15,906			706			704
	4. Plan Participants' Contributions		—			—			395			408
	5. Net Actuarial (Gain)/Loss due to Assumption Changes		38,496			14,450			5,981			497
	6. Net Actuarial (Gain)/Loss due to Plan Experience		2,338			5,428			924			357
	7. Benefit Payments from Fund ⁽¹⁾		(17,578		)	(21,831		)	(1,404		)	(1,678		)
	8. Benefit Payments Directly by Company		(335		)	(2,669		)	—			—
	9. Plan Amendments		10			16			—			—
	10. Other Adjustment		—			(105		)	(77		)	(84		)
	11. Benefit Obligation at End of Year		$	417,770		$	369,808		$	24,716		$	17,378


⁽¹⁾	Includes lump sum payments of $6.3 million and $11.2 million in 2017 and 2016, respectively, from our pension plan to eligible participants, which were former employees with vested benefits.

The increase in our pension and supplemental executive retirement plans obligation in 2017 compared to 2016 was primarily due to a decrease in the discount rate used to calculate the obligation and a lower amount of benefits paid from the fund. The increase in our other postretirement plan obligation was primarily due a decrease in the discount rate used to calculate the obligation. Table 11.8 below includes the actuarial assumptions used to calculate the benefit obligations of our plans for 2017 and 2016.

Tables 11.5 and 11.6 shows the changes in the fair value of the net assets available for plan benefits, and changes in other comprehensive income (loss) during 2017 and 2016.



	Table	11.5
Change in plan assets			Pension and Supplemental Executive Retirement Plans						Other Postretirement Benefits
	(in thousands)		12/31/2017			12/31/2016			12/31/2017			12/31/2016
	1. Fair Value of Plan Assets at Beginning of Year		$	360,900		$	350,107		$	70,408		$	65,568
	2. Company Contributions		9,435			11,369			—			—
	3. Plan Participants' Contributions		—			—			395			408
	4. Benefit Payments from Fund		(17,578		)	(21,831		)	(1,404		)	(1,678		)
	5. Benefit Payments paid directly by Company		(335		)	(2,669		)	—			—
	6. Actual Return on Assets		48,720			23,924			16,299			6,518
	7. Other Adjustment		—			—			(395		)	(408		)
	8. Fair Value of Plan Assets at End of Year		$	401,142		$	360,900		$	85,303		$	70,408



	Table	11.6
Change in accumulated other comprehensive income (loss) ("AOCI")			Pension and Supplemental Executive Retirement Plans						Other Postretirement Benefits
	(in thousands)		12/31/2017			12/31/2016			12/31/2017			12/31/2016
	1. AOCI in Prior Year		$	101,575		$	92,647		$	(18,079	)	$	(23,951	)
	2. Increase/(Decrease) in AOCI
	a. Recognized during year - Prior Service (Cost)/Credit		426			687			6,649			6,649
	b. Recognized during year - Net Actuarial (Losses)/Gains		(6,169		)	(5,856		)	—			—
	c. Occurring during year - Prior Service Cost		10			16			—			—
	d. Occurring during year - Net Actuarial Losses/(Gains)		12,212			15,358			(4,146		)	(777		)
	e. Occurring during year - Net Settlement Losses/(Gains)		—			(1,277		)	—			—
	f. Other adjustments		—			—			—			—
	3. AOCI in Current Year		$	108,054		$	101,575		$	(15,576	)	$	(18,079	)

Table 11.7 shows the amount of amortization on components of net periodic benefit costs expected to be recognized during the year ending December 31, 2018.



	Table	11.7
Amortization expected to be recognized during next fiscal year ending			Pension and Supplemental Executive Retirement Plans			Other Postretirement Benefits
	(In thousands)		12/31/2018			12/31/2018
	1. Amortization of Net Transition Obligation/(Asset)		$	—		$	—
	2. Amortization of Prior Service Cost/(Credit)		(349		)	(4,104		)
	3. Amortization of Net Losses/(Gains)		7,140			(183		)

The projected benefit obligations, net periodic benefit costs and accumulated postretirement benefit obligation for the plans were determined using the following weighted average assumptions.



	Table	11.8
Actuarial assumptions			Pension and Supplemental Executive Retirement Plans				Other Postretirement Benefits
			12/31/2017		12/31/2016		12/31/2017		12/31/2016
	Weighted-Average Assumptions Used to Determine
	Benefit Obligations at year end
	1. Discount Rate		3.75	%	4.30	%	3.55	%	3.95	%
	2. Rate of Compensation Increase		3.00	%	3.00	%	N/A		N/A

	Weighted-Average Assumptions Used to Determine
	Net Periodic Benefit Cost for Year
	1. Discount Rate		4.30	%	4.65	%	3.95	%	4.30	%
	2. Expected Long-term Return on Plan Assets		5.75	%	5.75	%	7.50	%	7.50	%
	3. Rate of Compensation Increase		3.00	%	3.00	%	N/A		N/A

	Assumed Health Care Cost Trend Rates at year end
	1. Health Care Cost Trend Rate Assumed for Next Year		N/A		N/A		6.50	%	6.50	%
	2. Rate to Which the Cost Trend Rate is Assumed to Decline (Ultimate Trend Rate)		N/A		N/A		5.00	%	5.00	%
	3. Year That the Rate Reaches the Ultimate Trend Rate		N/A		N/A		2024		2020

In selecting a discount rate, we performed a hypothetical cash flow bond matching exercise, matching our expected pension plan and postretirement medical plan cash flows, respectively, against a selected portfolio of high quality corporate bonds. The modeling was performed using a bond portfolio of noncallable bonds with at least $50 million outstanding. The average yield of these hypothetical bond portfolios was used as the benchmark for determining the discount rate. In selecting the expected long-term rate of return on assets, we considered the average rate of earnings expected on the classes of funds invested or to be invested to provide for the benefits of these plans. This included considering the trusts' targeted asset allocation for the year and the expected returns likely to be earned over the next 20 years.

The year-end asset allocations of the plans are shown in table 11.9 below.



	Table	11.9
Plan assets			Pension Plan				Other Postretirement Benefits
			12/31/2017		12/31/2016		12/31/2017		12/31/2016
	1. Equity Securities		21	%	23	%	100	%	100	%
	2. Debt Securities		79	%	77	%	—	%	—	%
	3. Total		100	%	100	%	100	%	100	%

In accordance with fair value guidance, we applied the following fair value hierarchy in order to measure fair value of our benefit plan assets:

Level 1 – Quoted prices for identical instruments in active markets that we can access. Financial assets utilizing Level 1 inputs include equity securities, mutual funds, money market funds, certain U.S. Treasury securities and exchange traded funds ("ETFs").

Level 2 – Quoted prices for similar instruments in active markets; quoted prices for identical or similar instruments in markets that are not active; and inputs, other than quoted prices, that are observable in the marketplace for the instrument. The observable inputs are used in valuation models to calculate the fair value of the instruments. Financial assets utilizing Level 2 inputs include certain municipal, corporate and foreign bonds, obligations of U.S. government corporations and agencies, and pooled equity accounts.

To determine the fair value of securities in Level 1 and Level 2 of the fair value hierarchy, independent pricing sources have been utilized. One price is provided per security based on observable market data. To ensure securities are appropriately classified in the fair value hierarchy, we review the pricing techniques and methodologies of the independent pricing sources and believe that their policies adequately consider market activity, either based on specific transactions for the issue valued or based on modeling of securities with similar credit quality, duration, yield and structure that were recently traded. A variety of inputs are utilized by the independent pricing sources including benchmark yields, reported trades, non-binding broker/dealer quotes, issuer spreads, two sided markets, benchmark securities, bids, offers and reference data including market research publications. Inputs may be weighted differently for any security, and not all inputs are used for each security evaluation. Market indicators, industry and economic events are also considered. This information is evaluated using a multidimensional pricing model. In addition, on a quarterly basis, we perform quality controls over values received from the pricing source (the “Trustee”) which include comparing values to other independent pricing sources. In addition, we review annually the Trustee’s auditor’s report on internal controls in order to determine that their controls around valuing securities are operating effectively. We have not made any adjustments to the prices obtained from the independent sources.

Tables 11.10a and 11.10b set forth by level, within the fair value hierarchy, the pension plan assets and related accrued investment income at fair value as of December 31, 2017 and 2016. There were no securities that utilized Level 3 inputs.



	Table	11.10a
Pension plan - current year	Assets at fair value as of December 31, 2017
Pension plan - current year	(in thousands)		Level 1		Level 2		Total
	Domestic Mutual Funds		$	1,006	$	—	$	1,006
	Corporate Bonds		—		202,840		202,840
	U.S. Government Securities		17,996		1,400		19,396
	Municipal Bonds		—		62,293		62,293
	Foreign Bonds		—		32,949		32,949
	ETFs		5,734		—		5,734
	Pooled Equity Accounts		—		76,924		76,924
	Total Assets at fair value		$	24,736	$	376,406	$	401,142



	Table	11.10b
Pension plan - prior year	Assets at fair value as of December 31, 2016
Pension plan - prior year	(in thousands)		Level 1		Level 2		Total
	Domestic Mutual Funds		$	11,805	$	—	$	11,805
	Corporate Bonds		—		178,412		178,412
	U.S. Government Securities		6,761		354		7,115
	Municipal Bonds		—		63,492		63,492
	Foreign Bonds		—		27,917		27,917
	ETFs		5,694		—		5,694
	Pooled Equity Accounts		—		66,465		66,465
	Total Assets at fair value		$	24,260	$	336,640	$	360,900

The pension plan has implemented a strategy to reduce risk through the use of a targeted funded ratio. The liability driven component is key to the asset allocation. The liability driven component seeks to align the duration of the fixed income asset allocation with the expected duration of the plan liabilities or benefit payments. Overall asset allocation is dynamic and specifies target allocation weights and ranges based on the funded status.

An improvement in funded status results in the de-risking of the portfolio, allocating more funds to fixed income and less to equity. A decline in funded status would result in a higher allocation to equity. The maximum equity allocation is 40%.

The equity investments utilize combinations of mutual funds, ETFs, and pooled equity account structures focused on the following strategies:



Strategy	Objective	Investment types
Return seeking growth	Funded ratio improvement over the long term	●	Global quality growth
Return seeking growth	Funded ratio improvement over the long term	●	Global low volatility
Return seeking bridge	Downside protection in the event of a declining equity market	●	Enduring asset
Return seeking bridge		●	Durable company

The fixed income objective is to preserve capital and to provide monthly cash flows for the payment of plan liabilities. Fixed income investments can include government, government agency, corporate, mortgage-backed, asset-backed, and municipal securities, and other classes of bonds. The duration of the fixed income portfolio has an objective of being within one year of the duration of the accumulated benefit obligation. The fixed income investments have an objective of a weighted average credit of A3/A-/A- by Moody’s, S&P, and Fitch, respectively.

Tables 11.11a and 11.11b set forth the other postretirement benefits plan assets at fair value as of December 31, 2017 and 2016. All are Level 1 assets.



	Table	11.11a
Other postretirement benefits plan - current year	Assets at fair value as of December 31, 2017
	(in thousands)		Level 1		Total
	Domestic Mutual Funds		$	64,489	$	64,489
	International Mutual Funds		20,814		20,814
	Total Assets at fair value		$	85,303	$	85,303



	Table	11.11b
Other postretirement benefits plan - prior year	Assets at fair value as of December 31, 2016
	(in thousands)		Level 1		Total
	Domestic Mutual Funds		$	54,426	$	54,426
	International Mutual Funds		15,982		15,982
	Total Assets at fair value		$	70,408	$	70,408

Our postretirement plan portfolio is designed to achieve the following objectives over each market cycle and for at least 5 years:


•	Total return should exceed growth in the Consumer Price Index by 5.75% annually


•	Achieve competitive investment results

The primary focus in developing asset allocation ranges for the portfolio is the assessment of the portfolio's investment objectives and the level of risk that is acceptable to obtain those objectives. To achieve these objectives the minimum and maximum allocation ranges for fixed income securities and equity securities are:



	Minimum		Maximum
Equities (long only)	70	%	100	%
Real estate	0	%	15	%
Commodities	0	%	10	%
Fixed income/Cash	0	%	10	%

Given the long term nature of this portfolio and the lack of any immediate need for significant cash flow, it is anticipated that the equity investments will consist of growth stocks and will typically be at the higher end of the allocation ranges above.

Investment in international mutual funds is limited to a maximum of 30% of the equity range. The allocation as of December 31, 2017 included 3% that was primarily invested in equity securities of emerging market countries and another 21% was invested in securities of companies primarily based in Europe and the Pacific Basin.

Tables 11.12 and 11.13 show the current and estimated future contributions and benefit payments.



	Table	11.12
Company contributions			Pension and Supplemental Executive Retirement Plans		Other Postretirement Benefits
	(in thousands)		12/31/2017		12/31/2017
	Company Contributions for the Year Ending:
	1. Current		$	9,435	$	—
	2. Current + 1		10,950		—



	Table	11.13
Benefit payments - total			Pension and Supplemental Executive Retirement Plans		Other Postretirement Benefits
	(in thousands)		12/31/2017		12/31/2017
	Actual Benefit Payments for the Year Ending:
	1. Current		$	17,913	$	1,086
	Expected Benefit Payments for the Year Ending:
	2. Current + 1		28,639		1,174
	3. Current + 2		33,127		1,368
	4. Current + 3		29,669		1,689
	5. Current + 4		31,085		1,944
	6. Current + 5		31,899		2,044
	7. Current + 6 - 10		151,512		11,914

Health care sensitivities

For measurement purposes for the other post retirement benefits plan, the increase in health care costs is estimated to be 6.5% for 2017 and 2018, decreasing to 5.0% by 2024 and remaining at this level beyond.

Assumed health care cost trend rates have a significant effect on the amounts reported for the other postretirement benefits plan. A 1 percentage point change in the health care trend rate assumption would have the following effects on other postretirement benefits:



	Table	11.14
Health care trend rate assumption	(in thousands)		1-Percentage Point Increase		1-Percentage Point Decrease
	Effect on total service and interest cost components		$	252	$	(217	)
	Effect on postretirement benefit obligation		3,093		(2,748		)

Profit sharing and 401(k)

We have a profit sharing and 401(k) savings plan for employees. At the discretion of the Board of Directors, we may make a contribution to the plan of up to 5% of each participant's eligible compensation. We provide a matching 401(k) savings contribution for employees on their before-tax contributions at a rate of 80% of the first $1,000 contributed and 40% of the next $2,000 contributed. For employees hired after January 1, 2014, the match is 100% up to 4% contributed. We recognized expenses related to these plans of $6.0 million, $5.9 million and $5.1 million in 2017, 2016 and 2015, respectively.

Income Taxes

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

Income Taxes

Net deferred tax assets and liabilities as of December 31, 2017 and 2016 are as follows:



	Table	12.1
Deferred tax assets and liabilities	(in thousands)		2017			2016
	Total deferred tax assets		$	258,663		$	636,449
	Total deferred tax liabilities		(24,282		)	(28,794		)
	Net deferred tax asset		$	234,381		$	607,655

Table 12.2 includes the components of the net deferred tax asset as of December 31, 2017 and 2016.



	Table	12.2
Deferred tax components	(in thousands)		2017			2016
	Unearned premium reserves		$	29,196		$	40,153
	Benefit plans		(7,162		)	(12,350		)
	Federal net operating loss		155,839			520,812
	Loss reserves		4,994			10,883
	Unrealized (appreciation) depreciation in investments		(7,782		)	11,211
	Mortgage investments		8,963			17,751
	Deferred compensation		7,265			12,517
	AMT credit carryforward		37,017			2,215
	Other, net		6,051			4,463
	Net deferred tax asset		$	234,381		$	607,655

We review the need to maintain a deferred tax asset valuation allowance on a quarterly basis. We analyze several factors, among which are the severity and frequency of operating losses, our capacity for the carryback or carryforward of any losses, the existence and current level of taxable operating income, operating results on a three year cumulative basis, the expected occurrence of future income or loss, the expiration dates of the carryforwards, the cyclical nature of our operating results, and available tax planning strategies. Based on our analysis, we reduced our benefit from income tax through the recognition of a valuation allowance from the first quarter of 2009 through the second quarter of 2015.

In the third quarter of 2015, we concluded that it was more likely than not that our deferred tax assets would be fully realizable and that the valuation allowance was no longer necessary and we reversed the valuation allowance. For the year ended December 31, 2015, we reversed $161.1 million of our valuation allowance based on income from 2015. The portion of the valuation allowance reversed related to deferred tax assets that are expected to be realized in future years, totaling $747.5 million, is treated as a discrete period item and is recognized as a component of the tax provision in continuing operations in the period of reversal. Furthermore, in determining the discrete period impact from the reversal, we removed the prior period disproportionate tax effects that had arisen in other comprehensive income because of the valuation allowance. This reduced the amount of tax benefit included in net income and resulted in an allocation of tax benefit of $60.8 million to components of other comprehensive income.

Table 12.3 provides a rollforward of our deferred tax asset valuation allowance for the year ended December 31, 2015.



	Table	12.3
Deferred tax valuation allowance rollforward	(in millions)		For the year ended December 31, 2015
	Balance at December 31, 2014		$	902.3

	Reduction in tax provision in current year		(161.1		)
	Amounts recorded in other comprehensive income in the current year		6.3
	Change in valuation allowance for deferred tax assets in the current year		(154.8		)

	Reduction in tax provision for amounts to be realized in future years		(686.7		)
	Amounts recorded in other comprehensive income to be realized in future years		(60.8		)
	Change in valuation allowance for deferred tax assets realizable in future years		(747.5		)

	Balance at December 31, 2015		$	—

Table 12.4 shows the effect of the change in valuation allowance on the provision for (benefit from) income taxes for the year ended December 31, 2015.



	Table	12.4
Provision for (benefit from) income taxes	(in thousands)		2015
	Provision for income taxes before valuation allowance		$	163,497
	Change in valuation allowance		(161,158		)
	Reversal of valuation allowance		(686,652		)
	Benefit from income taxes		$	(684,313	)

The change in the valuation allowance that was included in other comprehensive income was a decrease $54.5 million for the year ended December 31, 2015.

Giving full effect to the carryback of net operating losses for federal income tax purposes, we have approximately $742 million of net operating loss ("NOL") carryforwards on a regular tax basis as of December 31, 2017. Any unutilized carryforwards are scheduled to expire at the end of tax years 2032 and 2033.

Table 12.5 summarizes the components of the provision for (benefit from) income taxes:



	Table	12.5
Provision for (benefit from) income taxes	(in thousands)		2017		2016		2015
	Current Federal		$	73,348	$	9,470	$	8,067
	Deferred Federal		351,677		160,657		(686,652		)
	Other		3,710		2,070		(5,728		)
	Provision for (benefit from) income taxes		$	428,735	$	172,197	$	(684,313	)

Our income tax expense for 2017 reflects the remeasurement of our net deferred tax assets to reflect the lower corporate tax rate of 21% under the Tax Act, effective January 1, 2018. As a result of the lower tax rate, we have recorded a decrease to our net deferred tax assets of $133 million with a corresponding increase to our deferred income tax expense for the year ended December 31, 2017.

We paid $22.0 million, $4.5 million, and $5.4 million in federal income tax in 2017, 2016 and 2015, respectively.

Table 12.6 reconciles the federal statutory income tax rate to our effective tax provision (benefit) rate.



	Table	12.6
Effective tax rate reconciliation			2017		2016		2015
Effective tax rate reconciliation	Federal statutory income tax rate		35.0	%	35.0	%	35.0	%
	Additional income tax provision related to the rate decrease included in the Tax Act		17.0	%	—	%	—	%
	Additional income tax provision related to IRS litigation		3.7	%	0.1	%	0.1	%
	Valuation allowance		—	%	—	%	(173.8	)%
	Tax exempt municipal bond interest		(1.4	)%	(1.9	)%	(0.8	)%
	Other, net		0.4	%	0.3	%	(0.8	)%
	Effective tax provision (benefit) rate		54.7	%	33.5	%	(140.3	)%

As previously disclosed, the Internal Revenue Service ("IRS") completed examinations of our federal income tax returns for the years 2000 through 2007 and issued proposed assessments for taxes, interest and penalties related to our treatment of the flow-through income and loss from an investment in a portfolio of residual interests of Real Estate Mortgage Investment Conduits ("REMICs"). The IRS indicated that it did not believe that, for various reasons, we had established sufficient tax basis in the REMIC residual interests to deduct the losses from taxable income. We appealed these assessments within the IRS and in August 2010, we reached a tentative settlement agreement with the IRS which was not finalized.

In 2014, we received Notices of Deficiency (commonly referred to as “90 day letters”) covering the 2000-2007 tax years. The Notices of Deficiency reflect taxes and penalties related to the REMIC matters of $197.5 million and at December 31, 2017, there would also be interest related to these matters of approximately $205.0 million. In 2007, we made a payment of $65.2 million to the United States Department of the Treasury which will reduce any amounts we would ultimately owe. The Notices of Deficiency also reflect additional amounts due of $261.4 million, which are primarily associated with the disallowance of the carryback of the 2009 net operating loss to the 2004-2007 tax years. We believe the IRS included the carryback adjustments as a precaution to keep open the statute of limitations on collection of the tax that was refunded when this loss was carried back, and not because the IRS actually intends to disallow the carryback permanently. Depending on the outcome of this matter, additional state income taxes and state interest may become due when a final resolution is reached. As of December 31, 2017, those state taxes and interest would approximate $85.8 million. In addition, there could also be state tax penalties. Our total amount of unrecognized tax benefits as of December 31, 2017 is $142.8 million, which represents the tax benefits generated by the REMIC portfolio included in our tax returns that we have not taken benefit for in our financial statements, including any related interest.

We filed a petition with the U.S. Tax Court contesting most of the IRS’ proposed adjustments reflected in the Notices of Deficiency and the IRS filed an answer to our petition which continued to assert their claim. The case has twice been scheduled for trial and in each instance, the parties jointly filed, and the U.S. Tax Court approved (most recently in February 2016), motions for continuance to postpone the trial date. Also in February 2016, the U.S. Tax Court approved a joint motion to consolidate for trial, briefing, and opinion, our case with similar cases of Radian Group, Inc., as successor to Enhance Financial Services Group, Inc., et al. The parties have reached agreement on all issues in the case and in the fourth quarter of 2017, the IRS submitted documentation reflecting the terms of the agreement to the Joint Committee on Taxation ("JCT") for its review, which must be performed before a settlement can be completed. There is no assurance that a settlement will be completed. Based on information that we currently have regarding the status of our ongoing dispute, we recorded a provision for additional taxes and interest of $29.0 million in 2017.

Should a settlement not be completed, ongoing litigation to resolve our dispute with the IRS could be lengthy and costly in terms of legal fees and related expenses. We would need to make further adjustments, which could be material, to our tax provision and liabilities if our view of the probability of success in this matter changes, and the ultimate resolution of this matter could have a material negative impact on our effective tax rate, results of operations, cash flows, available assets and statutory capital. In this regard, see Note 14 - "Statutory Information."

Under current guidance, when evaluating a tax position for recognition and measurement, an entity shall presume that the tax position will be examined by the relevant taxing authority that has full knowledge of all relevant information. The interpretation adopts a benefit recognition model with a two-step approach, a more-likely-than-not threshold for recognition and derecognition, and a measurement attribute that is the greatest amount of benefit that is cumulatively greater than 50% likely of being realized. A reconciliation of the beginning and ending amount of unrecognized tax benefits is shown in table 12.7.



	Table	12.7
Unrecognized tax benefits reconciliation	(in thousands)		2017			2016		2015
	Balance at beginning of year		$	108,245		$	107,120	$	106,230
	Additions based on tax positions related to the current year		—			—		—
	Additions for tax positions of prior years		35,003			1,125		890
	Reductions for tax positions of prior years		(427		)	—		—
	Settlements		—			—		—
	Balance at end of year		$	142,821		$	108,245	$	107,120

The total amount of the unrecognized tax benefits related to our aforementioned REMIC issue, which would affect our effective tax rate, is $129.3 million. We recognize interest accrued and penalties related to unrecognized tax benefits in income taxes. During 2017, we recognized $23.1 million in interest. As of December 31, 2017 and 2016, we had $52.0 million and $28.9 million of accrued interest related to uncertain tax positions, respectively. The statute of limitations related to the consolidated federal income tax return is closed for all years prior to 2000. It is reasonably possible that our 2000-2007 federal tax case will be resolved, other than through litigation. If it is resolved under the basis of settlement as disclosed above, our total unrecognized tax benefits would be reduced by $142.8 million during 2018. After taking into account prior payments and the effect of available net operating loss carrybacks, any net cash outflows would approximate $55 million.

Shareholders' Equity	12 Months Ended
Shareholders' Equity	Dec. 31, 2017
Stockholders' Equity Note [Abstract]
Shareholders' Equity	Shareholders' Equity Change in accounting principle As of January 1, 2017, we adopted the updated guidance of "Improvements to Employee Share-Based Compensation Accounting." The adoption of this guidance resulted in an immaterial cumulative effect adjustment to our 2017 beginning retained earnings. For the year ending December 31, 2017, we adopted the updated guidance of "Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income." The adoption of this guidance resulted in a $10.4 million reclassification from accumulated other comprehensive loss to retained earnings during the fourth quarter of 2017. Each of these adoptions are more fully described in Note 3 - "Significant Accounting Policies." 2017 Capital transactions 2% Notes As described in Note 7 - "Debt" in April 2017 holders of approximately $202.5 million of the outstanding principal amount of our 2% Notes exercised their rights to convert their notes into shares of our common stock resulting in the delivery of approximately 29.1 million shares of our common stock to the holders. The transactions included the delivery of approximately 18.7 million from our treasury stock and an additional 10.4 million of newly issued shares. Shareholders' equity was increased by the carrying value of the notes at the time of conversion. 2016 Capital transactions As described in Note 7 - "Debt," in 2016 we issued approximately 18.3 million shares of our common stock as consideration for the purchase of certain of our 2% Notes. As of December 31, 2016, we had repurchased all of the shares issued as partial consideration for our 2% Notes repurchases. The weighted average price paid for the share repurchases was $8.03, which included commissions, and the aggregate purchase amount was $147.1 million. As described in Note 7 - "Debt" the purchase of a portion of our 9% Debentures by MGIC, and corresponding elimination of the purchased 9% Debentures in consolidation, resulted in a reduction to our consolidated shareholders' equity of approximately $6.3 million as of December 31, 2016. This reduction represents the allocated portion of the consideration paid to reacquire the equity component of the 9% Debentures, net of tax. The reduction was recognized in paid-in capital and was less than the amount ascribed to paid-in capital at original issuance of the 9% Debentures. Shareholders Rights Agreement Our Amended and Restated Rights Agreement dated July 23, 2015 seeks to diminish the risk that our ability to use our NOLs to reduce potential future federal income tax obligations may become substantially limited and to deter certain abusive takeover practices. The benefit of the NOLs would be substantially limited, and the timing of the usage of the NOLs could be substantially delayed, if we were to experience an “ownership change” as defined by Section 382 of the Internal Revenue Code. Under the Agreement each outstanding share of our Common Stock is accompanied by one Right. The Distribution Date occurs on the earlier of ten days after a public announcement that a person has become an Acquiring Person, or ten business days after a person announces or begins a tender offer in which consummation of such offer would result in a person becoming an Acquiring Person. An Acquiring Person is any person that becomes, by itself or together with its affiliates and associates, a beneficial owner of 5% or more of the shares of our Common Stock then outstanding, but excludes, among others, certain exempt and grandfathered persons as defined in the Agreement. The Rights are not exercisable until the Distribution Date. Each Right will initially entitle shareholders to buy one-tenth of one share of our Common Stock at a Purchase Price of $45 per full share (equivalent to $4.50 for each one-tenth share), subject to adjustment. Each exercisable Right (subject to certain limitations) will entitle its holder to purchase, at the Rights’ then-current Purchase Price, a number of our shares of Common Stock (or if after the Shares Acquisition Date, we are acquired in a business combination, common shares of the acquiror) having a market value at the time equal to twice the Purchase Price. The Rights will expire on August 1, 2018, or earlier as described in the Agreement. The Rights are redeemable at a price of $0.001 per Right at any time prior to the time a person becomes an Acquiring Person. Other than certain amendments, the Board of Directors may amend the Rights in any respect without the consent of the holders of the Rights.

Statutory Information

12 Months Ended

Dec. 31, 2017

Statutory Capital [Abstract]

Statutory Information

Statutory Accounting Principles

The statutory financial statements of our insurance companies are presented on the basis of accounting principles prescribed, or practices permitted, by the Office of the Commissioner of Insurance of the State of Wisconsin (the "OCI"), which has adopted the National Association of Insurance Commissioners ("NAIC") Statements of Statutory Accounting Principles ("SSAP") as the basis of its statutory accounting principles. In converting from statutory to GAAP, typical adjustments include deferral of policy acquisition costs, the inclusion of net unrealized holding gains or losses in shareholders' equity relating to fixed maturities and the inclusion of statutory non-admitted assets.

In addition to the typical adjustments from statutory to GAAP, mortgage insurance companies are required to maintain contingency loss reserves equal to 50% of premiums earned under SSAP and principles prescribed by the OCI, and such amounts cannot be withdrawn for a period of ten years except as permitted by insurance regulations. With regulatory approval, a mortgage guaranty insurance company may make early withdrawals from the contingency reserve when incurred losses exceed 35% of net premiums earned in a calendar year. For the year ended 2017, MGIC's losses incurred were 5% of net premiums earned. Changes in contingency loss reserves impact the statutory statement of operations. Contingency loss reserves are not reflected as liabilities under GAAP and changes in contingency loss reserves do not impact the GAAP statements of operations. A premium deficiency reserve that may be recorded on a GAAP basis when the present value of expected future losses and expenses exceeds the present value of expected future premiums and already established loss reserves, may not be recorded on a statutory basis if the present value of expected future premiums and already established loss reserves and statutory contingency reserves, exceeds the present value of expected future losses and expenses. On a GAAP basis, when calculating a premium deficiency reserve policies are grouped based on how they are acquired, serviced and measured. On a statutory basis, a premium deficiency reserve is calculated on all policies in force.

The statutory net income (loss), policyholders' surplus and contingency reserve liability of the insurance subsidiaries of our holding company are show in table 14.1 below. The statutory net loss in 2015 was driven by the dissolution of an MGIC non-insurance subsidiary. The surplus amounts included in the following table are the combined policyholders' surplus of our insurance operations as utilized in our risk-to-capital calculations.



	Table	14.1
Statutory financial information of holding company insurance subsidiaries			As of and for the Years Ended December 31,
	(in thousands)		2017		2016		2015
	Statutory net income (loss)		$	310,776	$	106,326	$	(72,767	)	⁽¹⁾
	Statutory policyholders' surplus		1,622,115		1,506,475		1,608,214			⁽¹⁾
	Contingency reserve		1,896,701		1,360,088		826,706


⁽¹⁾	The dissolution of an MGIC non-insurance subsidiary in 2015 had no impact on statutory surplus as the equity value of the investment was fully reflected in surplus as an unrealized loss prior to 2015.

The surplus contributions made to MGIC, dividends paid by MGIC, and distributions from other insurance subsidiaries to us, are shown in table 14.2 below.



	Table	14.2
Surplus contributions and dividends of insurance subsidiaries			Years Ended December 31,
	(in thousands)		2017		2016	2015
	Additions to the surplus of MGIC from parent company funds		$	—	36,025	—
	Dividends paid by MGIC to the parent company		$	140,000	64,000	—
	Distributions from other insurance subsidiaries to the parent company		$	—	52,001	38,500

Statutory Capital Requirements

The insurance laws of 16 jurisdictions, including Wisconsin, our domiciliary state, require a mortgage insurer to maintain a minimum amount of statutory capital relative to the RIF (or a similar measure) in order for the mortgage insurer to continue to write new business. We refer to these requirements as the “State Capital Requirements” and, together with the GSE Financial Requirements, the “Financial Requirements.” While they vary among jurisdictions, the most common State Capital Requirements allow for a maximum risk-to-capital ratio of 25 to 1. A risk-to-capital ratio will increase if (i) the percentage decrease in capital exceeds the percentage decrease in insured risk, or (ii) the percentage increase in capital is less than the percentage increase in insured risk. Wisconsin does not regulate capital by using a risk-to-capital measure but instead requires a minimum policyholder position ("MPP"). The “policyholder position” of a mortgage insurer is its net worth or surplus, contingency reserve and a portion of the reserves for unearned premiums.

At December 31, 2017, MGIC’s risk-to-capital ratio was 9.5 to 1, below the maximum allowed by the jurisdictions with State Capital Requirements and its policyholder position was $2.1 billion above the required MPP of $1.2 billion. In calculating our risk-to-capital ratio and MPP, we are allowed full credit for the risk ceded under our reinsurance transaction with a group of unaffiliated reinsurers. It is possible that under the revised State Capital Requirements discussed below, MGIC will not be allowed full credit for the risk ceded to the reinsurers. If MGIC is not allowed an agreed level of credit under either the State Capital Requirements or the PMIERs, MGIC may terminate the reinsurance agreement, without penalty. At this time, we expect MGIC to continue to comply with the current State Capital Requirements; however, you should read the rest of these financial statement footnotes for information about matters that could negatively affect such compliance.

At December 31, 2017, the risk-to-capital ratio of our combined insurance operations (which includes a reinsurance affiliate) was 10.5 to 1. Reinsurance transactions with our affiliate permit MGIC to write insurance with a higher coverage percentage than it could on its own under certain state-specific requirements. A higher risk-to-capital ratio on a combined basis may indicate that, in order for MGIC to continue to utilize reinsurance arrangements with its reinsurance affiliate, additional capital contributions to the affiliate could be needed.

The NAIC plans to revise the minimum capital and surplus requirements for mortgage insurers that are provided for in its Mortgage Guaranty Insurance Model Act. In May 2016, a working group of state regulators released an exposure draft of a risk-based capital framework to establish capital requirements for mortgage insurers, although no date has been established by which the NAIC must propose revisions to the capital requirements and certain items have not yet been completely addressed by the framework, including the treatment of ceded risk, minimum capital floors, and action level triggers. Currently we believe that the PMIERs contain the more restrictive capital requirements in most circumstances.

While MGIC currently meets the State Capital Requirements of Wisconsin and all other jurisdictions, it could be prevented from writing new business in the future in all jurisdictions if it fails to meet the State Capital Requirements of Wisconsin, or it could be prevented from writing new business in a particular jurisdiction if it fails to meet the State Capital Requirements of that jurisdiction and in each case MGIC does not obtain a waiver of such requirements. It is possible that regulatory action by one or more jurisdictions, including those that do not have specific State Capital Requirements, may prevent MGIC from continuing to write new insurance in such jurisdictions. If we are unable to write business in all jurisdictions, lenders may be unwilling to procure insurance from us anywhere. In addition, a lender’s assessment of the future ability of our insurance operations to meet the State Capital Requirements or the PMIERs may affect its willingness to procure insurance from us. A possible future failure by MGIC to meet the State Capital Requirements or the PMIERs will not necessarily mean that MGIC lacks sufficient resources to pay claims on its insurance liabilities. While we believe MGIC has sufficient claims paying resources to meet its claim obligations on its IIF on a timely basis, you should read the rest of these financial statement footnotes for information about matters that could negatively affect MGIC’s claims paying resources.

Dividend restrictions

In 2017, MGIC paid a total of $140 million in dividends to our holding company, and we expect MGIC to continue to pay quarterly dividends. During 2016, distributions of $52 million were paid to our holding company from other insurance subsidiaries. These distributions were completed in conjunction with the transfer of risk and the final dissolution of those insurance entities during 2016. Our holding company subsequently contributed the majority of the funds to MGIC in relation to the transfer of risk. During 2015, distributions of $38.5 million were paid to our holding company from other insurance subsidiaries.

MGIC is subject to statutory regulations as to payment of dividends. The maximum amount of dividends that MGIC may pay in any twelve-month period without regulatory approval by the OCI is the lesser of adjusted statutory net income or 10% of statutory policyholders' surplus as of the preceding calendar year end. Adjusted statutory net income is defined for this purpose to be the greater of statutory net income, net of realized investment gains, for the calendar year preceding the date of the dividend or statutory net income, net of realized investment gains, for the three calendar years preceding the date of the dividend less dividends paid within the first two of the preceding three calendar years. The OCI recognizes only statutory accounting principles prescribed, or practices permitted, by the State of Wisconsin for determining and reporting the financial condition and results of operations of an insurance company. The OCI has adopted certain prescribed accounting practices that differ from those found in other states. Specifically, Wisconsin domiciled companies record changes in the contingency reserves through the income statement as a change in underwriting deduction. As a result, in periods in which MGIC is increasing contingency reserves, statutory net income is reduced. For the year ended December 31, 2017, MGIC’s statutory net income was reduced by $473 million to account for the increase in contingency reserves.

Share-based Compensation Plans

12 Months Ended

Dec. 31, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Share-based Compensation Plans

We have an omnibus incentive plan that was adopted on April 23, 2015. The purpose of the 2015 plan is to motivate and incent performance by, and to retain the services of, key employees and non-employee directors through receipt of equity-based and other incentive awards under the plan. The maximum number of shares of stock that can be awarded under the 2015 plan is 10.0 million. Awards issued under the plan that are subsequently forfeited will not count against the limit on the maximum number of shares that may be issued under the plan. The 2015 plan provides for the award of stock options, stock appreciation rights, restricted stock and restricted stock units, as well as cash incentive awards. No awards may be granted after April 23, 2025 under the 2015 plan. The vesting provisions of options, restricted stock and restricted stock units are determined at the time of grant. Shares issued under the 2015 plan will be newly issued shares.

The compensation cost that has been charged against income for share-based plans was $14.9 million, $11.4 million, and $11.9 million for the years ended December 31, 2017, 2016 and 2015, respectively. The related income tax benefit recognized for share-based plans was $5.2 million, $4.0 million, and $4.2 million for the years ended December 31, 2017, 2016, and 2015, respectively.

Table 15.1 summarizes restricted stock or restricted stock unit (collectively called “restricted stock”) activity during 2017.



Table	15.1
		Weighted Average Grant Date Fair Market Value		Shares
Restricted stock outstanding at December 31, 2016		$	7.44	3,146,672
Granted		10.41		1,631,744
Vested		7.71		(1,409,347	)
Forfeited		8.43		(68,460	)
Restricted stock outstanding at December 31, 2017		$	8.78	3,300,609

At December 31, 2017, the 3.3 million shares of restricted stock outstanding consisted of 2.5 million shares that are subject to performance conditions (“performance shares”) and 0.8 million shares that are subject only to service conditions (“time vested shares”). The weighted-average grant date fair value of restricted stock granted during 2016 and 2015 was $5.66 and $9.03, respectively. The fair value of restricted stock granted is the closing price of the common stock on the New York Stock Exchange on the date of grant. The total fair value of restricted stock vested during 2017, 2016 and 2015 was $15.3 million, $12.2 million, and $17.2 million, respectively.

As of December 31, 2017, there was $13.2 million of total unrecognized compensation cost related to non-vested share-based compensation agreements granted under the plans. Of this total, $9.9 million of unrecognized compensation costs relate to performance shares and $3.3 million relates to time vested shares. A portion of the unrecognized costs associated with the performance shares may or may not be recognized in future periods, depending upon whether or not the performance and service conditions are met. The cost associated with the time vested shares is expected to be recognized over a weighted-average period of 1.5 years.

At December 31, 2017, 6.7 million shares were available for future grant under the 2015 Omnibus Incentive Plan.

Leases

12 Months Ended

Dec. 31, 2017

Leases [Abstract]

Leases

We lease certain office space as well as data processing equipment and autos under operating leases that expire during the next five years. Generally, rental payments are fixed.

Table 16.1 shows minimum the future operating lease payments as of December 31, 2017.



	Table	16.1
Minimum future operating lease payments	(in thousands)		Amount
	2018		$	808
	2019		823
	2020		583
	2021		48
	2022 and thereafter		—
	Total		$	2,262

Total rental expense under operating leases was $2.0 million in 2017, $2.1 million in 2016, and $2.2 million in 2015.

Litigation and Contingencies	12 Months Ended
Litigation and Contingencies	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Litigation and Contingencies	Litigation and Contingencies Before paying an insurance claim, we review the loan and servicing files to determine the appropriateness of the claim amount. When reviewing the files, we may determine that we have the right to rescind coverage on the loan. We refer to insurance rescissions and denials of claims collectively as “rescissions” and variations of that term. In addition, our insurance policies generally provide that we can reduce or deny a claim if the servicer did not comply with its obligations under our insurance policy. We call such reduction of claims “curtailments.” In recent quarters, an immaterial percentage of claims received in a quarter have been resolved by rescissions. In 2016 and 2017, curtailments reduced our average claim paid by approximately 5.5% and 5.6%, respectively. Our loss reserving methodology incorporates our estimates of future rescissions, curtailments, and reversals of rescissions and curtailments. A variance between ultimate actual rescission, curtailment, and reversal rates and our estimates, as a result of the outcome of litigation, settlements or other factors, could materially affect our losses. When the insured disputes our right to rescind coverage or curtail claims, we generally engage in discussions in an attempt to settle the dispute. If we are unable to reach a settlement, the outcome of a dispute ultimately would be determined by legal proceedings. Under ASC 450-20, until a liability associated with settlement discussions or legal proceedings becomes probable and can be reasonably estimated, we consider our claim payment or rescission resolved for financial reporting purposes and do not accrue an estimated loss. Where we have determined that a loss is probable and can be reasonably estimated we have recorded our best estimate of our probable loss. If we are not able to implement settlements we consider probable, we intend to defend MGIC vigorously against any related legal proceedings. In addition to matters for which we have recorded a probable loss, we are involved in other discussions and/or proceedings with insureds with respect to our claims paying practices. Although it is reasonably possible that when these matters are resolved we will not prevail in all cases, we are unable to make a reasonable estimate or range of estimates of the potential liability. We estimate the maximum exposure associated with matters where a loss is reasonably possible to be approximately $285 million, although we believe (but can give no assurance that) we will ultimately resolve these matters for significantly less than this amount. This estimate of our maximum exposure does not include interest or consequential or exemplary damages. Mortgage insurers, including MGIC, have been involved in litigation and regulatory actions related to alleged violations of the anti-referral fee provisions of the Real Estate Settlement Procedures Act, which is commonly known as RESPA, and the notice provisions of the Fair Credit Reporting Act, which is commonly known as FCRA. While these proceedings in the aggregate have not resulted in material liability for MGIC, there can be no assurance that the outcome of future proceedings, if any, under these laws would not have a material adverse affect on us. In addition, various regulators, including the CFPB, state insurance commissioners and state attorneys general may bring other actions seeking various forms of relief in connection with alleged violations of RESPA. The insurance law provisions of many states prohibit paying for the referral of insurance business and provide various mechanisms to enforce this prohibition. While we believe our practices are in conformity with applicable laws and regulations, it is not possible to predict the eventual scope, duration or outcome of any such reviews or investigations nor is it possible to predict their effect on us or the mortgage insurance industry. Through a non-insurance subsidiary, we utilize our underwriting skills to provide an outsourced underwriting service to our customers known as contract underwriting. As part of the contract underwriting activities, that subsidiary is responsible for the quality of the underwriting decisions in accordance with the terms of the contract underwriting agreements with customers. That subsidiary may be required to provide certain remedies to its customers if certain standards relating to the quality of our underwriting work are not met, and we have an established reserve for such future obligations. Claims for remedies may be made a number of years after the underwriting work was performed. The related contract underwriting remedy expense for the years ended December 31, 2017, 2016, and 2015, respectively, was immaterial to our consolidated financial statements. In addition to the matters described above, we are involved in other legal proceedings in the ordinary course of business. In our opinion, based on the facts known at this time, the ultimate resolution of these ordinary course legal proceedings will not have a material adverse effect on our financial position or consolidated results of operations. See Note 12 – “Income Taxes” for a description of federal income tax contingencies.

Unaudited Quarterly Financial Data

12 Months Ended

Dec. 31, 2017

Quarterly Financial Information Disclosure [Abstract]

Unaudited Quarterly Financial Data



	Table:	18.1a
Unaudited quarterly financial data - current year	2017:		Quarter												Full
	(in thousands, except per share data)		First			Second			Third			Fourth			Year
	Net premiums earned		$	229,103		$	231,136		$	237,083		$	237,425		$	934,747
	Investment income, net of expenses		29,477			29,716			30,402			31,276			120,871
	Realized (losses) gains		(122		)	(42		)	(47		)	460			249
	Other revenue		2,422			2,502			2,922			2,341			10,187
	Loss incurred, net		27,619			27,339			29,747			(30,996		)	53,709
	Underwriting and other expenses, net		59,304			55,292			56,146			57,042			227,784
	Loss on debt extinguishment		—			65			—			—			65
	Provision for income tax		84,159			61,994			64,440			218,142			428,735
	Net income		89,798			118,622			120,027			27,314			355,761
	Income per share ^{(a) (b)}:
	Basic		0.26			0.32			0.32			0.07			0.98
	Diluted		0.24			0.31			0.32			0.07			0.95



	Table:	18.1b
Unaudited quarterly financial data - prior year	2016:		Quarter									Full
	(in thousands, except per share data)		First		Second		Third		Fourth			Year
	Net premiums earned		$	221,341	$	231,456	$	237,376	$	235,053		$	925,226
	Investment income, net of expenses		27,809		27,248		27,515		28,094			110,666
	Realized gains (losses)		3,056		836		5,092		(52		)	8,932
	Other revenue		6,373		3,994		3,867		3,425			17,659
	Loss incurred, net		85,012		46,590		60,897		47,658			240,157
	Underwriting and other expenses, net		56,439		49,837		53,981		56,824			217,081
	Loss on debt extinguishment		13,440		1,868		75,223		—			90,531
	Provision for income tax		34,497		56,018		27,131		54,551			172,197
	Net income		69,191		109,221		56,618		107,487			342,517
	Income per share^{(a) (b)}:
	Basic		0.20		0.32		0.16		0.31			1.00
	Diluted		0.17		0.26		0.14		0.28			0.86


^(a)	Due to the use of weighted average shares outstanding when calculating earnings per share, the sum of the quarterly per share data may not equal the per share data for the year.


^(b)	In periods where convertible debt instruments are dilutive to earnings per share the “if-converted” method of computing diluted EPS requires an interest expense adjustment, net of tax, to net income available to shareholders. See Note 4 – “Earnings Per Share” for further discussion on our calculation of diluted EPS.

SCHEDULE I - SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES

12 Months Ended

Dec. 31, 2017

Summary of Investments, Other than Investments in Related Parties [Abstract]

SCHEDULE I - SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES

SCHEDULE I — SUMMARY OF INVESTMENTS -

OTHER THAN INVESTMENTS IN RELATED PARTIES

December 31, 2017




(In thousands) Type of Investment	Amortized Cost		Fair Value		Amount at which shown in the balance sheet
Fixed income:
Bonds:
United States Government and government agencies and authorities	$	179,850	$	178,846	$	178,846
States, municipalities and political subdivisions	2,105,063		2,152,524		2,152,524
Public utilities	222,619		222,806		222,806
Asset-backed securities	4,925		4,923		4,923
Collateralized loan obligations	100,798		101,023		101,023
Mortgage-backed	490,167		479,161		479,161
All other corporate bonds	1,842,856		1,844,032		1,844,032
Total fixed income	4,946,278		4,983,315		4,983,315

Equity securities:
Common stocks:
Industrial, miscellaneous and all other	7,223		7,246		7,246
Total equity securities	7,223		7,246		7,246

Total investments	$	4,953,501	$	4,990,561	$	4,990,561

SCHEDULE II - CONDENSED FINANCIAL INFORMATION OF REGISTRANT

12 Months Ended

Dec. 31, 2017

Condensed Financial Information of Parent Company Only Disclosure [Abstract]

SCHEDULE II - CONDENSED FINANCIAL INFORMATION OF REGISTRANT

CONDENSED BALANCE SHEETS

PARENT COMPANY ONLY




	December 31,
(In thousands)	2017			2016
ASSETS
Fixed income (amortized cost, 2017 – $195,846; 2016 – $247,396)	$	194,061		$	245,435
Cash and cash equivalents	22,247			37,666
Investment in subsidiaries, at equity in net assets	3,567,034			3,150,671
Accounts receivable - affiliates	1,414			780
Income taxes - current and deferred	192,570			289,703
Accrued investment income	1,941			1,749
Other assets	1,275			80
Total assets	$	3,980,542		$	3,726,084

LIABILITIES AND SHAREHOLDERS' EQUITY
Liabilities:
Senior notes	$	418,560		$	417,406
Convertible senior notes	—			349,461
Convertible junior subordinated debentures	389,522			389,522
Accrued interest	17,934			20,853
Total liabilities	826,016			1,177,242

Shareholders’ equity:
Common stock, (one dollar par value, shares authorized 1,000,000; shares issued 2017 – 370,567; 2016 – 359,400; outstanding 2017 – 370,567; 2016 – 340,663)	370,567			359,400
Paid-in capital	1,850,582			1,782,337
Treasury stock (shares at cost 2016 – 18,737)	—			(150,359		)
Accumulated other comprehensive loss, net of tax	(43,783		)	(75,100		)
Retained earnings	977,160			632,564
Total shareholders’ equity	3,154,526			2,548,842
Total liabilities and shareholders’ equity	$	3,980,542		$	3,726,084

See accompanying supplementary notes to Parent Company condensed financial statements.

MGIC INVESTMENT CORPORATION

SCHEDULE II - CONDENSED FINANCIAL INFORMATION OF REGISTRANT

CONDENSED STATEMENTS OF OPERATIONS

PARENT COMPANY ONLY




	Years Ended December 31,
(In thousands)	2017			2016			2015
Revenues:
Investment income, net of expenses	$	3,177		$	3,807		$	7,586
Net realized investment (losses) gains	(13		)	646			357
Total revenues	3,164			4,453			7,943

Expenses:
Operating expenses	642			1,409			582
Interest expense	65,972			64,598			68,932
Loss on debt extinguishment	65			82,234			507
Total expenses	66,679			148,241			70,021
Loss before tax	(63,515		)	(143,788		)	(62,078		)
Provision for (benefit from) income taxes	95,517			(52,575		)	(125,487		)
Equity in net income of subsidiaries	514,793			433,730			1,108,591
Net income	355,761			342,517			1,172,000
Other comprehensive income (loss), net of tax	41,739			(14,220		)	20,461
Comprehensive income	$	397,500		$	328,297		$	1,192,461

See accompanying supplementary notes to Parent Company condensed financial statements.

MGIC INVESTMENT CORPORATION

SCHEDULE II - CONDENSED FINANCIAL INFORMATION OF REGISTRANT

CONDENSED STATEMENTS OF CASH FLOWS

PARENT COMPANY ONLY




	Years Ended December 31,
(In thousands)	2017			2016			2015
Cash flows from operating activities:
Net income	$	355,761		$	342,517		$	1,172,000
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Equity in net income of subsidiaries	(514,793		)	(433,730		)	(1,108,591		)
Dividends received from subsidiaries	110,145			64,000			6,500
Deferred tax benefit	96,741			(55,988		)	(125,532		)
Loss on debt extinguishment	65			82,234			507
Other	18,716			16,722			31,701
Change in certain assets and liabilities:
Accounts receivable - affiliates	(634		)	158			(626		)
Income taxes receivable	297			3,602			(8,308		)
Accrued investment income	(192		)	1,951			(265		)
Accrued interest	(2,819		)	6,811			(652		)
Net cash provided by (used in) operating activities	63,287			28,277			(33,266		)
Cash flows from investing activities:
Capital distributions from subsidiaries	—			51,987			32,000
Capital contributions to subsidiaries	—			(36,025		)	—
Purchase of fixed income	(97,091		)	(194,751		)	(295,010		)
Sale of fixed income	176,960			330,142			386,385
Net cash provided by investing activities	79,869			151,353			123,375
Cash flows from financing activities:
Proceeds from revolving credit facility	150,000			—			—
Repayment of revolving credit facility	(150,000		)	—			—
Net proceeds from issuance of long-term debt	—			418,094			—
Repayment of long-term debt	—			—			(61,953		)
Repurchase of convertible senior notes	(150,124		)	(426,191		)	(12,004		)
Repurchase of common stock	—			(147,127		)	—
Payment of debt issuance costs	(1,630		)	(1,127		)	—
Payment of withholding taxes related to share-based compensation net share settlement	(6,821		)	(5,030		)	(7,242		)
Net cash used in financing activities	(158,575		)	(161,381		)	(81,199		)
Net (decrease) increase in cash and cash equivalents	(15,419		)	18,249			8,910
Cash and cash equivalents at beginning of year	37,666			19,417			10,507
Cash and cash equivalents at end of year	$	22,247		$	37,666		$	19,417

See accompanying supplementary notes to Parent Company condensed financial statements.

SCHEDULE II — CONDENSED FINANCIAL INFORMATION OF REGISTRANT

PARENT COMPANY ONLY

SUPPLEMENTARY NOTES

Note A

The accompanying Parent Company financial statements should be read in conjunction with the consolidated financial statements and notes to consolidated financial statements appearing this annual report.

Note B

Our insurance subsidiaries are subject to statutory regulations as to maintenance of policyholders’ surplus and payment of dividends. The maximum amount of dividends that the insurance subsidiaries may pay in any twelve-month period without regulatory approval by the OCI is the lesser of adjusted statutory net income or 10% of statutory policyholders’ surplus as of the preceding calendar year end. Adjusted statutory net income is defined for this purpose to be the greater of statutory net income, net of realized investment gains, for the calendar year preceding the date of the dividend or statutory net income, net of realized investment gains, for the three calendar years preceding the date of the dividend less dividends paid within the first two of the preceding three calendar years.

The payment of dividends from our insurance subsidiaries is the principal source of cash inflow for MGIC Investment Corporation, our holding company, other than investment income and raising capital in the public markets. The payment of dividends by our insurance subsidiaries is restricted by insurance regulation as discussed above. MGIC is the principal source of dividend-paying capacity and, in 2017, it paid a total of $140 million in dividends in cash and securities to our holding company, and we expect MGIC to continue to pay quarterly dividends. During 2016, MGIC paid a total of $64 million in dividends to our holding company and distributions of $52 million were paid to our holding company from other insurance subsidiaries. These distributions were completed in conjunction with the transfer of risk and the final dissolution of those insurance entities during 2016. Our holding company subsequently contributed the majority of the funds, approximately $36 million, to MGIC in relation to the transfer of risk. During 2015, distributions of $38.5 million, which includes dividends of $6.5 million, were paid to the holding company from other insurance subsidiaries. No contributions were made to our insurance subsidiaries in 2017 or 2015.

Note C

The senior notes and convertible junior subordinated debentures ("9% Debentures"), discussed in Note 7 – “Debt” to our consolidated financial statements, are obligations of MGIC Investment Corporation, our holding company, and not of its subsidiaries. In February 2016, MGIC purchased $132.7 million in aggregate principal of the 9% Debentures. The details of this transaction are discussed in Note 7 – “Debt” to our consolidated financial statements. The 9% Debentures owned by MGIC remain obligations of our holding company. The carrying amount outstanding of the 9% Debentures of $389.5 million is reported on the Parent Company only condensed balance sheet. For GAAP accounting purposes, the 9% Debentures owned by MGIC are eliminated in our consolidated financial statements.

- Definition

The entire disclosure for condensed financial information, including the financial position, cash flows, and the results of operations of the registrant (parent company) as of the same dates or for the same periods for which audited consolidated financial statements are being presented. Alternatively, the details of this disclosure can be reported by the specific parent company taxonomy elements, indicating the appropriate date and period contexts in an instance document.

+ References + Details

SCHEDULE IV - REINSURANCE

12 Months Ended

Dec. 31, 2017

Supplemental Schedule of Reinsurance Premiums for Insurance Companies [Abstract]

SCHEDULE IV - REINSURANCE

SCHEDULE IV — REINSURANCE

MORTGAGE INSURANCE PREMIUMS EARNED

Years Ended December 31, 2017, 2016 and 2015




(Dollars in thousands)	Gross Amount		Ceded to Other Companies		Assumed From Other Companies		Net Amount		Percentage of Amount Assumed to Net
Years ended December 31,
2017	$	1,059,973	$	125,735	$	509	$	934,747	0.1	%
2016	1,058,545		133,981		662		925,226		0.1	%
2015	997,892		102,848		1,178		896,222		0.1	%

Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2017

Accounting Policies [Abstract]

Basis of presentation

The accompanying consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America ("GAAP"), as codified in the Accounting Standards Codification ("ASC"). Our consolidated financial statements include the accounts of MGIC Investment Corporation and its majority-owned subsidiaries. Intercompany transactions and balances have been eliminated. In accordance with GAAP, we are required to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting periods. Actual results could differ from those estimates. We have considered subsequent events through the date of this filing.

Reclassifications

Certain reclassifications to 2016 and 2015 amounts have been made in the accompanying consolidated financial statements to conform to the 2017 presentation.

Cash and Cash Equivalents

We consider money market funds and investments with original maturities of three months or less to be cash equivalents.

Fair value measurements

In accordance with fair value accounting guidance, we applied the following fair value hierarchy in order to measure fair value for assets and liabilities:

The independent pricing sources utilize these approaches to determine the fair value of the instruments in Level 2 of the fair value hierarchy based on type of instrument:

Investments


▪	our intent to sell the security or whether it is more likely than not that we will be required to sell the security before recovery of its amortized cost basis;


▪	the present value of the discounted cash flows we expect to collect compared to the amortized cost basis of the security;


▪	extent and duration of the decline;


▪	failure of the issuer to make scheduled interest or principal payments;


▪	change in rating below investment grade; and


▪	adverse conditions specifically related to the security, an industry, or a geographic area.

Home office and equipment

Deferred Insurance Policy Acquisition Costs

Loss Reserves

Premium Deficiency Reserve

Share-Based Compensation

Earnings per Share

Recent accounting and reporting developments

Accounting standards effective in 2017, or early adopted, and relevant to our financial statements



	Table	3.1
Standard / Interpretation					Effective date
Standard / Interpretation	Amended Standards
	ASC 220		Income Statement - Reporting Comprehensive Income
			•	ASU 2018-02 - Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income	January 1, 2019
	ASC 718		Compensation - Stock Compensation
			•	ASU 2016-09 - Improvements to Employee Share-Based Compensation Accounting	January 1, 2017

Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income

◦

Improvements to Employee Share-Based Compensation Accounting


•	Tax effects related to share-based compensation are made through the statement of operations at the time of settlement instead of recognizing them in paid-in capital.


◦	Adoption impact: We recognized discrete tax benefits of $1.6 million in the provision for income taxes on our statement of operations for the year ended December 31, 2017 related to excess tax benefits upon vesting of share-based awards during the period.


•	Recognition of a tax benefit is no longer required to be delayed until it reduces current taxes payable.

◦


•	Tax related cash flows resulting from share-based compensation are to be reported as operating activities on the statement of cash flows, instead of as an inflow from financing activities and an outflow from operating activities.


◦	Adoption impact: We reclassified excess tax benefits related to share-based compensation for 2016 and 2015 to operating activities from financing activities.


•	Shares withheld by an employer for tax-withholding purposes upon vesting of equity compensation represents a cash outflow required to be classified as a financing activity on the statements of cash flows.


◦	Adoption impact: We reclassified employee taxes paid for withheld shares for 2016 and 2015 to financing activities from operating activities.

Prospective Accounting Standards

Table 3.2 shows the relevant new amendments to accounting standards, which are not yet effective or adopted.



	Table	3.2
Standard / Interpretation					Effective date
Standard / Interpretation	Amended Standards
	ASC 718		Compensation - Stock Compensation
			•	ASU 2017-09 - Scope of Modification Accounting	January 1, 2018
	ASC 715		Compensation - Retirement Benefits
			•	ASU 2017-07 - Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost	January 1, 2018
	ASC 310		Receivables - Nonrefundable Fees and Other Costs
			•	ASU 2017-08 - Premium Amortization on Purchased Callable Debt Securities	January 1, 2019
	ASC 326		Financial Instruments - Credit Losses
			•	ASU 2016-13 - Measurement of Credit Losses on Financial Instruments	January 1, 2020
	ASC 825		Financial Instruments - Overall
			•	ASU 2016-01 - Recognition and Measurement of Financial Assets and Financial Liabilities	January 1, 2018

Stock Compensation - Scope of Modification Accounting

Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost

Premium Amortization on Purchased Callable Debt Securities

Measurement of Credit Losses on Financial Instruments

Recognition and Measurement of Financial Assets and Financial Liabilities

Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2017

Accounting Policies [Abstract]

Schedule of Recent Accounting and Reporting Developments



	Table	3.1
Standard / Interpretation					Effective date
Standard / Interpretation	Amended Standards
	ASC 220		Income Statement - Reporting Comprehensive Income
			•	ASU 2018-02 - Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income	January 1, 2019
	ASC 718		Compensation - Stock Compensation
			•	ASU 2016-09 - Improvements to Employee Share-Based Compensation Accounting	January 1, 2017

Schedule of Prospective Accounting Standards, Not Yet Effective Or Adopted

Table 3.2 shows the relevant new amendments to accounting standards, which are not yet effective or adopted.



	Table	3.2
Standard / Interpretation					Effective date
Standard / Interpretation	Amended Standards
	ASC 718		Compensation - Stock Compensation
			•	ASU 2017-09 - Scope of Modification Accounting	January 1, 2018
	ASC 715		Compensation - Retirement Benefits
			•	ASU 2017-07 - Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost	January 1, 2018
	ASC 310		Receivables - Nonrefundable Fees and Other Costs
			•	ASU 2017-08 - Premium Amortization on Purchased Callable Debt Securities	January 1, 2019
	ASC 326		Financial Instruments - Credit Losses
			•	ASU 2016-13 - Measurement of Credit Losses on Financial Instruments	January 1, 2020
	ASC 825		Financial Instruments - Overall
			•	ASU 2016-01 - Recognition and Measurement of Financial Assets and Financial Liabilities	January 1, 2018

Earnings per Share (Tables)

12 Months Ended

Dec. 31, 2017

Earnings Per Share [Abstract]

Calculation of earnings (loss) per share

Table 4.1 reconciles basic and diluted EPS amounts:



	Table	4.1
Earnings per share			Years Ended December 31,
Earnings per share	(In thousands, except per share data)		2017		2016		2015
	Basic earnings per share:
	Net income		$	355,761	$	342,517	$	1,172,000
	Weighted average common shares outstanding - basic		362,380		342,890		339,552
	Basic earnings per share		$	0.98	$	1.00	$	3.45
	Diluted earnings per share:
	Net income		$	355,761	$	342,517	$	1,172,000
	Interest expense, net of tax ⁽¹⁾:
	2% Notes		907		6,111		7,928
	5% Notes		1,709		6,362		12,228
	9% Debentures		15,027		15,893		22,786
	Diluted income available to common shareholders		$	373,404	$	370,883	$	1,214,942
	Weighted-average shares - Basic		362,380		342,890		339,552
	Effect of dilutive securities:
	Unvested restricted stock units		1,493		1,470		2,113
	2% Notes		8,317		54,450		71,917
	5% Notes		3,548		13,107		25,603
	9% Debentures		19,028		20,075		28,854
	Weighted average common shares outstanding - diluted		394,766		431,992		468,039
	Diluted income per share		$	0.95	$	0.86	$	2.60


⁽¹⁾	Interest expense for the years ended December 31, 2017, 2016 and 2015 has been tax effected at a rate of 35%.

Investments (Tables)

12 Months Ended

Dec. 31, 2017

Investments [Abstract]

Amortized cost, gross unrealized gains and losses and fair value of investment portfolio

The amortized cost, gross unrealized gains and losses and fair value of the investment portfolio as of December 31, 2017 and 2016 are shown below:



	Table	5.1a
Details of investments by category - current year			December 31, 2017
Details of investments by category - current year	(In thousands)		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses ⁽¹⁾			Fair Value
	U.S. Treasury securities and obligations of U.S. government corporations and agencies		$	179,850	$	274	$	(1,278	)	$	178,846
	Obligations of U.S. states and political subdivisions		2,105,063		56,210		(8,749		)	2,152,524
	Corporate debt securities		2,065,475		10,532		(9,169		)	2,066,838
	ABS		4,925		—		(2		)	4,923
	RMBS		189,153		60		(7,364		)	181,849
	CMBS		301,014		1,204		(4,906		)	297,312
	CLOs		100,798		304		(79		)	101,023
	Total debt securities		4,946,278		68,584		(31,547		)	4,983,315
	Equity securities		7,223		39		(16		)	7,246
	Total investment portfolio		$	4,953,501	$	68,623	$	(31,563	)	$	4,990,561



	Table	5.1b
Details of investments by category - prior year			December 31, 2016
Details of investments by category - prior year	(In thousands)		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses ⁽¹⁾			Fair Value
	U.S. Treasury securities and obligations of U.S. government corporations and agencies		$	73,847	$	407	$	(724	)	$	73,530
	Obligations of U.S. states and political subdivisions		2,147,458		20,983		(25,425		)	2,143,016
	Corporate debt securities		1,756,461		6,059		(18,610		)	1,743,910
	ABS		59,519		74		(28		)	59,565
	RMBS		231,733		102		(7,626		)	224,209
	CMBS		327,042		769		(7,994		)	319,817
	CLOs		121,151		226		(202		)	121,175
	Total debt securities		4,717,211		28,620		(60,609		)	4,685,222
	Equity securities		7,144		8		(24		)	7,128
	Total investment portfolio		$	4,724,355	$	28,628	$	(60,633	)	$	4,692,350


⁽¹⁾	There were no OTTI losses recorded in other comprehensive (loss) income as of December 31, 2017 and 2016.

Amortized cost and fair values of debt securities by contractual maturity

Table 5.2 compares the amortized cost and fair values of debt securities, by contractual maturity, as of December 31, 2017.



	Table	5.2
Debt securities maturity schedule			December 31, 2017
	(In thousands)		Amortized Cost		Fair Value
	Due in one year or less		$	541,755	$	541,695
	Due after one year through five years		1,547,712		1,544,943
	Due after five years through ten years		925,751		929,883
	Due after ten years		1,335,170		1,381,687
			4,350,388		4,398,208

	ABS		4,925		4,923
	RMBS		189,153		181,849
	CMBS		301,014		297,312
	CLOs		100,798		101,023
	Total as of December 31, 2017		$	4,946,278	$	4,983,315

Aging of the fair values of securities in an unrealized loss position

Tables 5.3a and 5.3b show the components of our unrealized losses on our investment portfolio in the amount of $32 million and $61 million as of December 31, 2017 and 2016, respectively.



	Table	5.3a
Investments unrealized losses - current year	December 31, 2017		Less Than 12 Months					12 Months or Greater					Total
Investments unrealized losses - current year	(In thousands)		Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
	U.S. Treasury securities and obligations of U.S. government corporations and agencies		$	144,042	$	(796	)	$	31,196	$	(482	)	$	175,238	$	(1,278	)
	Obligations of U.S. states and political subdivisions		505,311		(3,624		)	211,684		(5,125		)	716,995		(8,749		)
	Corporate debt securities		932,350		(4,288		)	200,716		(4,881		)	1,133,066		(9,169		)
	ABS		4,923		(2		)	—		—			4,923		(2		)
	RMBS		14,979		(280		)	166,329		(7,084		)	181,308		(7,364		)
	CMBS		51,096		(358		)	138,769		(4,548		)	189,865		(4,906		)
	CLOs		14,243		(7		)	3,568		(72		)	17,811		(79		)
	Equity securities		226		(2		)	431		(14		)	657		(16		)
	Total investment portfolio		$	1,667,170	$	(9,357	)	$	752,693	$	(22,206	)	$	2,419,863	$	(31,563	)



	Table	5.3b
Investments unrealized losses - prior year	December 31, 2016		Less Than 12 Months					12 Months or Greater					Total
Investments unrealized losses - prior year	(In thousands)		Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
	U.S. Treasury securities and obligations of U.S. government corporations and agencies		$	48,642	$	(724	)	$	—	$	—		$	48,642	$	(724	)
	Obligations of U.S. states and political subdivisions		1,136,676		(24,918		)	13,681		(507		)	1,150,357		(25,425		)
	Corporate debt securities		915,777		(16,771		)	35,769		(1,839		)	951,546		(18,610		)
	ABS		3,366		(28		)	656		—			4,022		(28		)
	RMBS		46,493		(857		)	171,326		(6,769		)	217,819		(7,626		)
	CMBS		205,545		(7,529		)	38,587		(465		)	244,132		(7,994		)
	CLOs		13,278		(73		)	34,760		(129		)	48,038		(202		)
	Equity securities		568		(15		)	137		(9		)	705		(24		)
	Total investment portfolio		$	2,370,345	$	(50,915	)	$	294,916	$	(9,718	)	$	2,665,261	$	(60,633	)

Net investment income

The source of net investment income is shown in Table 5.4 below.



	Table	5.4
Investment income by source	(In thousands)		2017			2016			2015
Investment income by source	Fixed income		$	122,105		$	112,513		$	105,882
	Equity securities		206			182			208
	Cash equivalents		1,447			754			191
	Other		620			433			455
	Investment income		124,378			113,882			106,736
	Investment expenses		(3,507		)	(3,216		)	(2,995		)
	Net investment income		$	120,871		$	110,666		$	103,741

Net realized investment gains (losses), including impairment losses, and change in unrealized gains (losses) of investments

The net realized investment gains (table 5.5) and the change in unrealized gains (losses) of investments (table 5.6) are shown below.



	Table	5.5
Net realized investment gains	(In thousands)		2017		2016		2015
Net realized investment gains	Fixed income		$	228	$	5,310	$	28,335
	Equity securities		21		3,622		26
	Other		—		—		—
	Total net realized investment gains		$	249	$	8,932	$	28,361



	Table	5.6
Change in unrealized gains (losses)	(In thousands)		2017			2016			2015
	Fixed income		$	69,026		$	(5,403	)	$	(33,687	)
	Equity securities		39			(36		)	(32		)
	Other		(13		)	14			1
	Total increase (decrease) in unrealized gains/losses		$	69,052		$	(5,425	)	$	(33,718	)

Gross realized gains, gross realized losses and impairment losses

Gross realized gains and losses on investments are shown in Table 5.7 below.



	Table	5.7
Gross realized investment gains	(In thousands)		2017			2016			2015
Gross realized investment gains	Gross realized gains		$	1,599		$	11,909		$	30,039
	Gross realized losses		(1,350		)	(2,977		)	(1,678		)
	Net realized gains on securities		$	249		$	8,932		$	28,361

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2017

Fair Value Disclosures [Abstract]

Fair value measurements for items measured at fair value

Assets measured at fair value included those listed, by hierarchy level, in the following tables as of December 31, 2017 and 2016:



	Table	6.1a
Fair value hierarchy - current year	December 31, 2017
Fair value hierarchy - current year	(In thousands)		Fair Value		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
	U.S. Treasury securities and obligations of U.S. government corporations and agencies		$	178,846	$	81,598	$	97,248	$	—
	Obligations of U.S. states and political subdivisions		2,152,524		—		2,152,253		271
	Corporate debt securities		2,066,838		—		2,066,838		—
	ABS		4,923		—		4,923		—
	RMBS		181,849		—		181,849		—
	CMBS		297,312		—		297,312		—
	CLOs		101,023		—		101,023		—
	Total debt securities		4,983,315		81,598		4,901,446		271
	Equity securities ⁽¹⁾		7,246		2,978		—		4,268
	Total investments		$	4,990,561	$	84,576	$	4,901,446	$	4,539
	Real estate acquired ⁽²⁾		$	12,713	$	—	$	—	$	12,713



	Table	6.1b
Fair value hierarchy - prior year	December 31, 2016
Fair value hierarchy - prior year	(In thousands)		Fair Value		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
	U.S. Treasury securities and obligations of U.S. government corporations and agencies		$	73,530	$	30,690	$	42,840	$	—
	Obligations of U.S. states and political subdivisions		2,143,016		—		2,142,325		691
	Corporate debt securities		1,743,910		—		1,743,910		—
	ABS		59,565		—		59,565		—
	RMBS		224,209		—		224,209		—
	CMBS		319,817		—		319,817		—
	CLOs		121,175		—		121,175		—
	Total debt securities		4,685,222		30,690		4,653,841		691
	Equity securities ⁽¹⁾		7,128		2,860		—		4,268
	Total investments		$	4,692,350	$	33,550	$	4,653,841	$	4,959
	Real estate acquired ⁽²⁾		$	11,748	$	—	$	—	$	11,748


⁽¹⁾	Equity securities in Level 3 are carried at cost, which approximates fair value.


⁽²⁾	Real estate acquired through claim settlement, which is held for sale, is reported in other assets on the consolidated balance sheets.

Reconciliation of beginning and ending balance for assets and liabilities measured at fair value with significant unobservable inputs (level 3)



	Table	6.2a
Development of assets and liabilities classified within level 3 - current year	(In thousands)		Debt Securities			Equity Securities		Total Investments			Real Estate Acquired
	Balance at December 31, 2016		$	691		$	4,268	$	4,959		$	11,748
	Total realized/unrealized gains (losses):
	Included in earnings and reported as losses incurred, net		—			—		—			(1,315		)
	Purchases		—			—		—			34,749
	Sales		(420		)	—		(420		)	(32,469		)
	Balance at December 31, 2017		$	271		$	4,268	$	4,539		$	12,713



	Table	6.2b
Development of assets and liabilities classified within level 3 - prior year	(In thousands)		Debt Securities			Equity Securities			Total Investments			Real Estate Acquired
	Balance at December 31, 2015		$	1,228		$	2,855		$	4,083		$	12,149
	Total realized/unrealized gains (losses):
	Included in earnings and reported as net realized investment gains		—			3,579			3,579			—
	Included in earnings and reported as losses incurred, net		—			—			—			(1,142		)
	Purchases		—			4,258			4,258			36,859
	Sales		(537		)	(6,424		)	(6,961		)	(36,118		)
	Balance at December 31, 2016		$	691		$	4,268		$	4,959		$	11,748



	Table	6.2c
Development of assets and liabilities classified within level 3 - two years prior	(In thousands)		Debt Securities			Equity Securities		Total Investments			Real Estate Acquired
	Balance at December 31, 2014		$	1,846		$	321	$	2,167		$	12,658
	Total realized/unrealized gains (losses):
	Included in earnings and reported as losses incurred, net		—			—		—			(2,322		)
	Purchases		7			2,534		2,541			34,624
	Sales		(625		)	—		(625		)	(32,811		)
	Balance at December 31, 2015		$	1,228		$	2,855	$	4,083		$	12,149

Schedule of carrying value and fair value of financial liabilities measured on a recurring basis

Table 6.3 compares the carrying value and fair value of our financial liabilities disclosed, but not carried, at fair value as of December 31, 2017 and 2016.



	Table	6.3
Fair value measurements - liabilities			December 31, 2017				December 31, 2016
	(In thousands)		Carrying Value		Fair Value		Carrying Value		Fair Value
	FHLB Advance		$	155,000	$	152,124	$	155,000	$	151,905
	5% Notes		—		—		144,789		147,679
	2% Notes		—		—		204,672		308,605
	5.75% Notes		418,560		465,473		417,406		445,987
	9% Debentures		256,872		353,507		256,872		323,040
	Total financial liabilities		$	830,432	$	971,104	$	1,178,739	$	1,377,216

Debt (Tables)

12 Months Ended

Dec. 31, 2017

Debt Disclosure [Abstract]

Schedule of debt

Table 7.1 shows the par value of our long-term debt obligations and their aggregate carrying values as of December 31, 2017 and 2016.



	Table	7.1
Long-term debt obligations			December 31,
	(In millions)		2017			2016
	FHLB Advance		$	155.0		$	155.0
	5% Notes		—			145.0
	2% Notes		—			207.6
	5.75% Notes		425.0			425.0
	9% Debentures		256.9			256.9
	Long-term debt, par value		836.9			1,189.5
	Debt issuance costs		(6.5		)	(10.8		)
	Long-term debt, carrying value		$	830.4		$	1,178.7

Interest Payments Made

Table 7.2 shows the interest payments, on a consolidated basis, for our debt obligations outstanding during 2017 and 2016.



	Table	7.2
Interest payments on debt obligations			Years Ended December 31,
	(In millions)		2017		2016
	Revolving credit facility		$	0.9	$	—
	FHLB Advance		3.0		2.4
	5% Notes		3.6		10.6
	2% Notes		2.1		9.1
	5.75% Notes		25.1		—
	9% Debentures		23.1		27.4
	Total interest payments		$	57.8	$	49.5

Loss Reserves (Tables)

12 Months Ended

Dec. 31, 2017

Insurance Loss Reserves [Abstract]

Reconciliation of beginning and ending loss reserves

Table 8.1 provides a reconciliation of beginning and ending loss reserves for each of the past three years:



	Table	8.1
Development of reserves for losses and loss adjustment expenses	(In thousands)		2017			2016			2015
	Reserve at beginning of year		$	1,438,813		$	1,893,402		$	2,396,807
	Less reinsurance recoverable		50,493			44,487			57,841
	Net reserve at beginning of year		1,388,320			1,848,915			2,338,966

	Losses incurred:
	Losses and LAE incurred in respect of delinquent notices received in:
	Current year		284,913			387,815			453,849
	Prior years ⁽¹⁾		(231,204		)	(147,658		)	(110,302		)
	Total losses incurred		53,709			240,157			343,547

	Losses paid:
	Losses and LAE paid in respect of delinquent notices received in:
	Current year		11,267			14,823			25,980
	Prior years		493,300			689,258			823,058
	Reinsurance terminations ⁽²⁾		301			(3,329		)	(15,440		)
	Total losses paid		504,868			700,752			833,598
	Net reserve at end of year		937,161			1,388,320			1,848,915
	Plus reinsurance recoverables		48,474			50,493			44,487
	Reserve at end of year		$	985,635		$	1,438,813		$	1,893,402


⁽¹⁾	A negative number for prior year losses incurred indicates a redundancy of prior year loss reserves. See table 8.2 below for more information about prior year loss development.

⁽²⁾

Prior year development of the reserves

Table 8.2 below shows the development of reserves in 2017, 2016 and 2015 for previously received delinquencies.



	Table	8.2
Reserve development on previously received delinquencies	(In millions)		2017			2016			2015
	Decrease in estimated claim rate on primary delinquencies		$	(248	)	$	(148	)	$	(141	)
	Increase in estimated severity on primary delinquencies		9			9			43
	Change in estimates related to pool reserves, LAE reserves, reinsurance and other		8			(9		)	(12		)
	Total prior year loss development ⁽¹⁾		$	(231	)	$	(148	)	$	(110	)


⁽¹⁾	A negative number for prior year loss development indicates a redundancy of prior year loss reserves.

Rollforward of primary default inventory



	Table	8.3
Delinquent inventory rollforward			2017		2016		2015
	Delinquent inventory at beginning of year		50,282		62,633		79,901
	New Notices		68,268		67,434		74,315
	Cures		(61,094	)	(65,516	)	(73,610	)
	Paids (including those charged to a deductible or captive)		(9,206	)	(12,367	)	(16,004	)
	Rescissions and denials		(357	)	(629	)	(848	)
	Other items removed from inventory		(1,337	)	(1,273	)	(1,121	)
	Delinquent inventory at end of year		46,556		50,282		62,633

Aging of the primary default inventory

The number of consecutive months that a borrower has been delinquent is shown in the table below.



	Table	8.4
Delinquent inventory - consecutive months delinquent			December 31,
			2017			2016			2015
	3 months or less		17,119	37	%	12,194	24	%	13,053	21	%
	4 - 11 months		12,050	26	%	13,450	27	%	15,763	25	%
	12 months or more⁽¹⁾		17,387	37	%	24,638	49	%	33,817	54	%
	Total primary delinquent inventory		46,556	100	%	50,282	100	%	62,633	100	%

	Primary claims received inventory included in ending delinquent inventory		954	2	%	1,385	3	%	2,769	4	%


⁽¹⁾	Approximately 45%, 47% and 50% of the primary delinquent inventory delinquent for 12 consecutive months or more has been delinquent for at least 36 consecutive months as of December 31, 2017, 2016 and 2015, respectively.

Number of payments delinquent

The number of payments that a borrower is delinquent is shown in table 8.5 below.



	Table	8.5
Delinquent inventory - number of payments delinquent			December 31,
			2017			2016			2015
	3 payments or less		21,678	46	%	18,419	36	%	20,360	33	%
	4 - 11 payments		12,446	27	%	12,892	26	%	15,092	24	%
	12 payments or more		12,432	27	%	18,971	38	%	27,181	43	%
	Total primary delinquent inventory		46,556	100	%	50,282	100	%	62,633	100	%

Reinsurance (Tables)

12 Months Ended

Dec. 31, 2017

Reinsurance Disclosures [Abstract]

Effect of reinsurance agreements on premiums earned and losses incurred

Table 9.1 below shows the effect of all reinsurance agreements on premiums earned and losses incurred as reflected in the consolidated statements of operations.



	Table	9.1
Reinsurance			Years ended December 31,
	(In thousands)		2017			2016			2015
	Premiums earned:
	Direct		$	1,059,973		$	1,058,545		$	997,892
	Assumed		509			662			1,178
	Ceded		(125,735		)	(133,981		)	(102,848		)
	Net premiums earned		$	934,747		$	925,226		$	896,222

	Losses incurred:
	Direct		$	74,727		$	273,207		$	369,680
	Assumed		183			1,138			1,552
	Ceded		(21,201		)	(34,188		)	(27,685		)
	Net losses incurred		$	53,709		$	240,157		$	343,547

Quota share reinsurance, excluding captive agreements

Table 9.2 provides a summary of our quota share reinsurance agreements, excluding captive agreements, for 2017, 2016 and 2015.



	Table	9.2
Quota share reinsurance			Years ended December 31,
Quota share reinsurance	(In thousands)		2017		2016		2015 ⁽³⁾
	Ceded premiums written, net of profit commission ⁽¹⁾		$	120,974	$	125,460	$	41,233
	Ceded premiums earned, net of profit commission ⁽¹⁾		120,974		125,460		88,587
	Ceded losses incurred		22,336		30,201		17,484
	Ceding commissions ⁽²⁾		49,321		47,629		30,816
	Profit commission		125,629		112,685		112,847


⁽¹⁾	Since July 1, 2015, premiums are ceded on an earned and received basis as defined in our QSR Transactions currently in effect.


⁽²⁾	Ceding commissions are reported within Other underwriting and operating expenses, net on the consolidated statements of operations.


⁽³⁾	The year ended December 31, 2015 includes the non-recurring impact of commuting our 2013 QSR Transaction (see "2013 QSR Transaction" above for additional information). The commutation had no impact on ceded losses incurred.

Other Comprehensive Income (Loss) (Tables)

12 Months Ended

Dec. 31, 2017

Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]

Other comprehensive income

The pretax components of our other comprehensive income (loss) and related income tax (expense) benefit for the years ended December 31, 2017, 2016 and 2015 are included in table 10.1 below:



	Table	10.1
Components of other comprehensive income (loss)	(In thousands)		2017			2016			2015
	Net unrealized investment gains (losses) arising during the year		$	69,052		$	(5,425	)	$	(33,718	)
	Income tax (expense) benefit		(21,505		)	1,776			11,738
	Valuation allowance ⁽¹⁾		—			—			62,383
	Net of taxes		47,547			(3,649		)	40,403

	Net changes in benefit plan assets and obligations		(8,983		)	(14,799		)	(12,818		)
	Income tax benefit		3,144			5,179			4,487
	Valuation allowance ⁽¹⁾		—			—			(7,383		)
	Net of taxes		(5,839		)	(9,620		)	(15,714		)

	Net changes in unrealized foreign currency translation adjustment		45			(1,463		)	(5,699		)
	Income tax (expense) benefit		(14		)	512			2,000
	Valuation allowance ⁽¹⁾		—			—			(529		)
	Net of taxes		31			(951		)	(4,228		)

	Total other comprehensive income (loss)		60,114			(21,687		)	(52,235		)
	Total income tax (expense) benefit, net of valuation allowance		(18,375		)	7,467			72,696
	Total other comprehensive income (loss), net of tax		$	41,739		$	(14,220	)	$	20,461


⁽¹⁾	See Note 12 – “Income Taxes” for a discussion of the valuation allowance recorded against deferred tax assets in 2015.

Reclassification out of accumulated other comprehensive income



	Table	10.2
Reclassifications from AOCL	(In thousands)		2017			2016			2015
	Reclassification adjustment for net realized (losses) gains included in net income ⁽¹⁾		$	(2,580	)	$	6,207		$	11,693
	Income tax benefit (expense)		903			(2,050		)	(4,076		)
	Valuation allowance ⁽²⁾		—			—			3,635
	Net of taxes		(1,677		)	4,157			11,252

	Reclassification adjustment related to benefit plan assets and obligations ⁽³⁾		906			1,480			2,184
	Income tax (expense)		(317		)	(518		)	(764		)
	Valuation allowance ⁽²⁾		—			—			574
	Net of taxes		589			962			1,994

	Reclassification adjustment related to foreign currency ⁽⁴⁾		—			1,467			—
	Income tax (expense)		—			(513		)	—
	Net of taxes		—			954			—

	Total reclassifications		(1,674		)	9,154			13,877
	Total income tax benefit (expense), net of valuation allowance		586			(3,081		)	(631		)
	Total reclassifications, net of tax		$	(1,088	)	$	6,073		$	13,246


⁽¹⁾	(Decreases) increases Net realized investment gains on the consolidated statements of operations.


⁽²⁾	See Note 12 – “Income Taxes” for a discussion of the valuation allowance recorded against deferred tax assets in 2015.


⁽³⁾	Decreases (increases) Other underwriting and operating expenses, net on the consolidated statements of operations.


⁽⁴⁾	Increases (decreases) Other revenue on the consolidated statements of operations.

Accumulated other comprehensive income (loss)

A rollforward of AOCL for the years ended December 31, 2017, 2016, and 2015, including amounts reclassified from AOCL, is included in table 10.3 below.



	Table	10.3
Rollforward of AOCL	(In thousands)		Net unrealized gains and losses on available-for-sale securities			Net benefit plan assets and obligations recognized in shareholders' equity			Net unrealized foreign currency translation			Total AOCL
	Balance, December 31, 2014, net of tax		$	(57,551	)	$	(28,938	)	$	5,148		$	(81,341	)
	Other comprehensive income (loss) before reclassifications		51,655			(13,720		)	(4,228		)	33,707
	Less: Amounts reclassified from AOCL		11,252			1,994			—			13,246
	Balance, December 31, 2015, net of tax		(17,148		)	(44,652		)	920			(60,880		)
	Other comprehensive income (loss) before reclassifications		508			(8,658		)	3			(8,147		)
	Less: Amounts reclassified from AOCL		4,157			962			954			6,073
	Balance, December 31, 2016, net of tax		(20,797		)	(54,272		)	(31		)	(75,100		)
	Other comprehensive income (loss) before reclassifications		45,870			(5,250		)	31			40,651
	Less: Amounts reclassified from AOCL		(1,677		)	589			—			(1,088		)
	Less: Amounts reclassified for lower enacted corporate tax rate		(2,525		)	12,947			—			10,422
	Balance, December 31, 2017, net of tax		$	29,275		$	(73,058	)	$	—		(43,783		)

Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2017

Retirement Benefits [Abstract]

Components of net periodic benefit cost

The following tables 11.1, 11.2, and 11.3 provide the components of aggregate annual net periodic benefit cost for each of the years ended December 31, 2017, 2016, and 2015 and changes in the benefit obligation and the funded status of the pension, supplemental executive retirement and other postretirement benefit plans as recognized in the consolidated balance sheets as of December 31, 2017 and 2016.



	Table	11.1
Components of net periodic benefit cost			Pension and Supplemental Executive Retirement Plans									Other Postretirement Benefits
Components of net periodic benefit cost	(in thousands)		12/31/2017			12/31/2016			12/31/2015			12/31/2017			12/31/2016			12/31/2015
	1. Company Service Cost		$	9,556		$	9,130		$	10,256		$	813		$	751		$	833
	2. Interest Cost		15,475			15,906			15,847			706			704			697
	3. Expected Return on Assets		(20,099		)	(19,508		)	(21,109		)	(5,248		)	(4,886		)	(4,991		)
	4. Other Adjustments		—			—			—			—			—			—
	Subtotal		4,932			5,528			4,994			(3,729		)	(3,431		)	(3,461		)
	5. Amortization of:
	a. Net Transition Obligation/(Asset)		—			—			—			—			—			—
	b. Net Prior Service Cost/(Credit)		(426		)	(687		)	(845		)	(6,649		)	(6,649		)	(6,649		)
	c. Net Losses/(Gains)		6,169			5,856			5,485			—			—			(175		)
	Total Amortization		5,743			5,169			4,640			(6,649		)	(6,649		)	(6,824		)
	6. Net Periodic Benefit Cost		10,675			10,697			9,634			(10,378		)	(10,080		)	(10,285		)
	7. Cost of settlements		—			1,277			3,172			—			—			—
	8. Total Expense for Year		$	10,675		$	11,974		$	12,806		$	(10,378	)	$	(10,080	)	$	(10,285	)

Development of funded status



	Table	11.2
Development of funded status			Pension and Supplemental Executive Retirement Plans						Other Postretirement Benefits
	(in thousands)		12/31/2017			12/31/2016			12/31/2017			12/31/2016
	Actuarial Value of Benefit Obligations
	1. Measurement Date		12/31/2017			12/31/2016			12/31/2017			12/31/2016
	2. Accumulated Benefit Obligation		$	411,996		$	360,423		$	24,716		$	17,378

	Funded Status/Asset (Liability) on the Consolidated Balance Sheet
	1. Projected Benefit Obligation		$	(417,770	)	$	(369,808	)	$	(24,716	)	$	(17,378	)
	2. Plan Assets at Fair Value		401,142			360,900			85,303			70,408
	3. Funded Status - Overfunded/Asset		N/A			N/A			$	60,587		$	53,030
	4. Funded Status - Underfunded/Liability		(16,628		)	(8,908		)	N/A			N/A



	Table	11.3
Accumulated other comprehensive income (loss)			Pension and Supplemental Executive Retirement Plans						Other Postretirement Benefits
	(in thousands)		12/31/2017			12/31/2016			12/31/2017			12/31/2016
	1. Net Actuarial (Gain)/Loss		$	109,904		$	103,861		$	(10,234	)	$	(6,088	)
	2. Net Prior Service Cost/(Credit)		(1,850		)	(2,286		)	(5,342		)	(11,991		)
	3. Net Transition Obligation/(Asset)		—			—			—			—
	4. Total at Year End		$	108,054		$	101,575		$	(15,576	)	$	(18,079	)

Change in projected benefit obligation

Table 11.4 shows the changes in the projected benefit obligation for 2017 and 2016.



	Table	11.4
Change in projected benefit / accumulated benefit obligation			Pension and Supplemental Executive Retirement Plans						Other Postretirement Benefits
	(in thousands)		12/31/2017			12/31/2016			12/31/2017			12/31/2016
	1. Benefit Obligation at Beginning of Year		$	369,808		$	349,483		$	17,378		$	16,423
	2. Company Service Cost		9,556			9,130			813			751
	3. Interest Cost		15,475			15,906			706			704
	4. Plan Participants' Contributions		—			—			395			408
	5. Net Actuarial (Gain)/Loss due to Assumption Changes		38,496			14,450			5,981			497
	6. Net Actuarial (Gain)/Loss due to Plan Experience		2,338			5,428			924			357
	7. Benefit Payments from Fund ⁽¹⁾		(17,578		)	(21,831		)	(1,404		)	(1,678		)
	8. Benefit Payments Directly by Company		(335		)	(2,669		)	—			—
	9. Plan Amendments		10			16			—			—
	10. Other Adjustment		—			(105		)	(77		)	(84		)
	11. Benefit Obligation at End of Year		$	417,770		$	369,808		$	24,716		$	17,378


⁽¹⁾	Includes lump sum payments of $6.3 million and $11.2 million in 2017 and 2016, respectively, from our pension plan to eligible participants, which were former employees with vested benefits.

Change in plan assets

Tables 11.5 and 11.6 shows the changes in the fair value of the net assets available for plan benefits, and changes in other comprehensive income (loss) during 2017 and 2016.



	Table	11.5
Change in plan assets			Pension and Supplemental Executive Retirement Plans						Other Postretirement Benefits
	(in thousands)		12/31/2017			12/31/2016			12/31/2017			12/31/2016
	1. Fair Value of Plan Assets at Beginning of Year		$	360,900		$	350,107		$	70,408		$	65,568
	2. Company Contributions		9,435			11,369			—			—
	3. Plan Participants' Contributions		—			—			395			408
	4. Benefit Payments from Fund		(17,578		)	(21,831		)	(1,404		)	(1,678		)
	5. Benefit Payments paid directly by Company		(335		)	(2,669		)	—			—
	6. Actual Return on Assets		48,720			23,924			16,299			6,518
	7. Other Adjustment		—			—			(395		)	(408		)
	8. Fair Value of Plan Assets at End of Year		$	401,142		$	360,900		$	85,303		$	70,408

Change in accumulated other comprehensive income (AOCI)



	Table	11.6
Change in accumulated other comprehensive income (loss) ("AOCI")			Pension and Supplemental Executive Retirement Plans						Other Postretirement Benefits
	(in thousands)		12/31/2017			12/31/2016			12/31/2017			12/31/2016
	1. AOCI in Prior Year		$	101,575		$	92,647		$	(18,079	)	$	(23,951	)
	2. Increase/(Decrease) in AOCI
	a. Recognized during year - Prior Service (Cost)/Credit		426			687			6,649			6,649
	b. Recognized during year - Net Actuarial (Losses)/Gains		(6,169		)	(5,856		)	—			—
	c. Occurring during year - Prior Service Cost		10			16			—			—
	d. Occurring during year - Net Actuarial Losses/(Gains)		12,212			15,358			(4,146		)	(777		)
	e. Occurring during year - Net Settlement Losses/(Gains)		—			(1,277		)	—			—
	f. Other adjustments		—			—			—			—
	3. AOCI in Current Year		$	108,054		$	101,575		$	(15,576	)	$	(18,079	)

Amortizations expected to be recognized during next fiscal year

Table 11.7 shows the amount of amortization on components of net periodic benefit costs expected to be recognized during the year ending December 31, 2018.



	Table	11.7
Amortization expected to be recognized during next fiscal year ending			Pension and Supplemental Executive Retirement Plans			Other Postretirement Benefits
	(In thousands)		12/31/2018			12/31/2018
	1. Amortization of Net Transition Obligation/(Asset)		$	—		$	—
	2. Amortization of Prior Service Cost/(Credit)		(349		)	(4,104		)
	3. Amortization of Net Losses/(Gains)		7,140			(183		)

Actuarial assumptions

The projected benefit obligations, net periodic benefit costs and accumulated postretirement benefit obligation for the plans were determined using the following weighted average assumptions.



	Table	11.8
Actuarial assumptions			Pension and Supplemental Executive Retirement Plans				Other Postretirement Benefits
			12/31/2017		12/31/2016		12/31/2017		12/31/2016
	Weighted-Average Assumptions Used to Determine
	Benefit Obligations at year end
	1. Discount Rate		3.75	%	4.30	%	3.55	%	3.95	%
	2. Rate of Compensation Increase		3.00	%	3.00	%	N/A		N/A

	Weighted-Average Assumptions Used to Determine
	Net Periodic Benefit Cost for Year
	1. Discount Rate		4.30	%	4.65	%	3.95	%	4.30	%
	2. Expected Long-term Return on Plan Assets		5.75	%	5.75	%	7.50	%	7.50	%
	3. Rate of Compensation Increase		3.00	%	3.00	%	N/A		N/A

	Assumed Health Care Cost Trend Rates at year end
	1. Health Care Cost Trend Rate Assumed for Next Year		N/A		N/A		6.50	%	6.50	%
	2. Rate to Which the Cost Trend Rate is Assumed to Decline (Ultimate Trend Rate)		N/A		N/A		5.00	%	5.00	%
	3. Year That the Rate Reaches the Ultimate Trend Rate		N/A		N/A		2024		2020

Year-end asset allocations of the plans

The year-end asset allocations of the plans are shown in table 11.9 below.



	Table	11.9
Plan assets			Pension Plan				Other Postretirement Benefits
			12/31/2017		12/31/2016		12/31/2017		12/31/2016
	1. Equity Securities		21	%	23	%	100	%	100	%
	2. Debt Securities		79	%	77	%	—	%	—	%
	3. Total		100	%	100	%	100	%	100	%

Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]

Schedule of investment allocation strategies

The equity investments utilize combinations of mutual funds, ETFs, and pooled equity account structures focused on the following strategies:



Strategy	Objective	Investment types
Return seeking growth	Funded ratio improvement over the long term	●	Global quality growth
Return seeking growth	Funded ratio improvement over the long term	●	Global low volatility
Return seeking bridge	Downside protection in the event of a declining equity market	●	Enduring asset
Return seeking bridge		●	Durable company

Minimum and maximum allocation ranges for fixed income securities and equity securities



	Minimum		Maximum
Equities (long only)	70	%	100	%
Real estate	0	%	15	%
Commodities	0	%	10	%
Fixed income/Cash	0	%	10	%

Actual and estimated future contributions and actual and estimated future benefit payments

Tables 11.12 and 11.13 show the current and estimated future contributions and benefit payments.



	Table	11.12
Company contributions			Pension and Supplemental Executive Retirement Plans		Other Postretirement Benefits
	(in thousands)		12/31/2017		12/31/2017
	Company Contributions for the Year Ending:
	1. Current		$	9,435	$	—
	2. Current + 1		10,950		—



	Table	11.13
Benefit payments - total			Pension and Supplemental Executive Retirement Plans		Other Postretirement Benefits
	(in thousands)		12/31/2017		12/31/2017
	Actual Benefit Payments for the Year Ending:
	1. Current		$	17,913	$	1,086
	Expected Benefit Payments for the Year Ending:
	2. Current + 1		28,639		1,174
	3. Current + 2		33,127		1,368
	4. Current + 3		29,669		1,689
	5. Current + 4		31,085		1,944
	6. Current + 5		31,899		2,044
	7. Current + 6 - 10		151,512		11,914

Effect of a 1% change in the health care trend rate assumption

A 1 percentage point change in the health care trend rate assumption would have the following effects on other postretirement benefits:



	Table	11.14
Health care trend rate assumption	(in thousands)		1-Percentage Point Increase		1-Percentage Point Decrease
	Effect on total service and interest cost components		$	252	$	(217	)
	Effect on postretirement benefit obligation		3,093		(2,748		)

Pension Plan

Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]

Fair value of plan assets



	Table	11.10a
Pension plan - current year	Assets at fair value as of December 31, 2017
Pension plan - current year	(in thousands)		Level 1		Level 2		Total
	Domestic Mutual Funds		$	1,006	$	—	$	1,006
	Corporate Bonds		—		202,840		202,840
	U.S. Government Securities		17,996		1,400		19,396
	Municipal Bonds		—		62,293		62,293
	Foreign Bonds		—		32,949		32,949
	ETFs		5,734		—		5,734
	Pooled Equity Accounts		—		76,924		76,924
	Total Assets at fair value		$	24,736	$	376,406	$	401,142



	Table	11.10b
Pension plan - prior year	Assets at fair value as of December 31, 2016
Pension plan - prior year	(in thousands)		Level 1		Level 2		Total
	Domestic Mutual Funds		$	11,805	$	—	$	11,805
	Corporate Bonds		—		178,412		178,412
	U.S. Government Securities		6,761		354		7,115
	Municipal Bonds		—		63,492		63,492
	Foreign Bonds		—		27,917		27,917
	ETFs		5,694		—		5,694
	Pooled Equity Accounts		—		66,465		66,465
	Total Assets at fair value		$	24,260	$	336,640	$	360,900

Other Postretirement Benefit Plan

Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]

Fair value of plan assets

Tables 11.11a and 11.11b set forth the other postretirement benefits plan assets at fair value as of December 31, 2017 and 2016. All are Level 1 assets.



	Table	11.11a
Other postretirement benefits plan - current year	Assets at fair value as of December 31, 2017
	(in thousands)		Level 1		Total
	Domestic Mutual Funds		$	64,489	$	64,489
	International Mutual Funds		20,814		20,814
	Total Assets at fair value		$	85,303	$	85,303



	Table	11.11b
Other postretirement benefits plan - prior year	Assets at fair value as of December 31, 2016
	(in thousands)		Level 1		Total
	Domestic Mutual Funds		$	54,426	$	54,426
	International Mutual Funds		15,982		15,982
	Total Assets at fair value		$	70,408	$	70,408

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

Net deferred tax assets and liabilities

Net deferred tax assets and liabilities as of December 31, 2017 and 2016 are as follows:



	Table	12.1
Deferred tax assets and liabilities	(in thousands)		2017			2016
	Total deferred tax assets		$	258,663		$	636,449
	Total deferred tax liabilities		(24,282		)	(28,794		)
	Net deferred tax asset		$	234,381		$	607,655

Components of the net deferred tax asset (liability)

Table 12.2 includes the components of the net deferred tax asset as of December 31, 2017 and 2016.



	Table	12.2
Deferred tax components	(in thousands)		2017			2016
	Unearned premium reserves		$	29,196		$	40,153
	Benefit plans		(7,162		)	(12,350		)
	Federal net operating loss		155,839			520,812
	Loss reserves		4,994			10,883
	Unrealized (appreciation) depreciation in investments		(7,782		)	11,211
	Mortgage investments		8,963			17,751
	Deferred compensation		7,265			12,517
	AMT credit carryforward		37,017			2,215
	Other, net		6,051			4,463
	Net deferred tax asset		$	234,381		$	607,655

Summary of valuation allowance

Table 12.3 provides a rollforward of our deferred tax asset valuation allowance for the year ended December 31, 2015.



	Table	12.3
Deferred tax valuation allowance rollforward	(in millions)		For the year ended December 31, 2015
	Balance at December 31, 2014		$	902.3

	Reduction in tax provision in current year		(161.1		)
	Amounts recorded in other comprehensive income in the current year		6.3
	Change in valuation allowance for deferred tax assets in the current year		(154.8		)

	Reduction in tax provision for amounts to be realized in future years		(686.7		)
	Amounts recorded in other comprehensive income to be realized in future years		(60.8		)
	Change in valuation allowance for deferred tax assets realizable in future years		(747.5		)

	Balance at December 31, 2015		$	—

Tax provision (benefit)

Table 12.4 shows the effect of the change in valuation allowance on the provision for (benefit from) income taxes for the year ended December 31, 2015.



	Table	12.4
Provision for (benefit from) income taxes	(in thousands)		2015
	Provision for income taxes before valuation allowance		$	163,497
	Change in valuation allowance		(161,158		)
	Reversal of valuation allowance		(686,652		)
	Benefit from income taxes		$	(684,313	)

Components of the provision for (benefit from) income taxes

Table 12.5 summarizes the components of the provision for (benefit from) income taxes:



	Table	12.5
Provision for (benefit from) income taxes	(in thousands)		2017		2016		2015
	Current Federal		$	73,348	$	9,470	$	8,067
	Deferred Federal		351,677		160,657		(686,652		)
	Other		3,710		2,070		(5,728		)
	Provision for (benefit from) income taxes		$	428,735	$	172,197	$	(684,313	)

Reconciliation of federal statutory income tax rate

Table 12.6 reconciles the federal statutory income tax rate to our effective tax provision (benefit) rate.



	Table	12.6
Effective tax rate reconciliation			2017		2016		2015
Effective tax rate reconciliation	Federal statutory income tax rate		35.0	%	35.0	%	35.0	%
	Additional income tax provision related to the rate decrease included in the Tax Act		17.0	%	—	%	—	%
	Additional income tax provision related to IRS litigation		3.7	%	0.1	%	0.1	%
	Valuation allowance		—	%	—	%	(173.8	)%
	Tax exempt municipal bond interest		(1.4	)%	(1.9	)%	(0.8	)%
	Other, net		0.4	%	0.3	%	(0.8	)%
	Effective tax provision (benefit) rate		54.7	%	33.5	%	(140.3	)%

Reconciliation of unrecognized tax benefits

A reconciliation of the beginning and ending amount of unrecognized tax benefits is shown in table 12.7.



	Table	12.7
Unrecognized tax benefits reconciliation	(in thousands)		2017			2016		2015
	Balance at beginning of year		$	108,245		$	107,120	$	106,230
	Additions based on tax positions related to the current year		—			—		—
	Additions for tax positions of prior years		35,003			1,125		890
	Reductions for tax positions of prior years		(427		)	—		—
	Settlements		—			—		—
	Balance at end of year		$	142,821		$	108,245	$	107,120

Statutory Information (Tables)

12 Months Ended

Dec. 31, 2017

Statutory Capital [Abstract]

Summary of amounts disclosed under statutory accounting practices



	Table	14.1
Statutory financial information of holding company insurance subsidiaries			As of and for the Years Ended December 31,
	(in thousands)		2017		2016		2015
	Statutory net income (loss)		$	310,776	$	106,326	$	(72,767	)	⁽¹⁾
	Statutory policyholders' surplus		1,622,115		1,506,475		1,608,214			⁽¹⁾
	Contingency reserve		1,896,701		1,360,088		826,706


⁽¹⁾	The dissolution of an MGIC non-insurance subsidiary in 2015 had no impact on statutory surplus as the equity value of the investment was fully reflected in surplus as an unrealized loss prior to 2015.

The surplus contributions made to MGIC, dividends paid by MGIC, and distributions from other insurance subsidiaries to us, are shown in table 14.2 below.



	Table	14.2
Surplus contributions and dividends of insurance subsidiaries			Years Ended December 31,
	(in thousands)		2017		2016	2015
	Additions to the surplus of MGIC from parent company funds		$	—	36,025	—
	Dividends paid by MGIC to the parent company		$	140,000	64,000	—
	Distributions from other insurance subsidiaries to the parent company		$	—	52,001	38,500

- Definition

Tabular disclosure of how the entity's reporting under GAAP as of the balance sheet date differs from the results based on prescribed and permitted accounting practices of the state or country of domicile in which a relevant statutory filing is made, or differences in results based on the National Association of Insurance Commissioners (NAIC) prescribed practices, or a combination thereof. Describes the accounting practices used and the related monetary effect on statutory surplus, net income, and risk-based capital. If an insurance enterprise's risk-based capital would have triggered a regulatory event had it not used a permitted practice, that fact is disclosed in the financial statements. Permitted statutory accounting practices include practices not prescribed but allowed by the domiciliary state insurance department regulatory authority.

+ References + Details

Unaudited Quarterly Financial Data (Tables)

12 Months Ended

Dec. 31, 2017

Quarterly Financial Information Disclosure [Abstract]

Unaudited quarterly financial data



	Table:	18.1a
Unaudited quarterly financial data - current year	2017:		Quarter												Full
	(in thousands, except per share data)		First			Second			Third			Fourth			Year
	Net premiums earned		$	229,103		$	231,136		$	237,083		$	237,425		$	934,747
	Investment income, net of expenses		29,477			29,716			30,402			31,276			120,871
	Realized (losses) gains		(122		)	(42		)	(47		)	460			249
	Other revenue		2,422			2,502			2,922			2,341			10,187
	Loss incurred, net		27,619			27,339			29,747			(30,996		)	53,709
	Underwriting and other expenses, net		59,304			55,292			56,146			57,042			227,784
	Loss on debt extinguishment		—			65			—			—			65
	Provision for income tax		84,159			61,994			64,440			218,142			428,735
	Net income		89,798			118,622			120,027			27,314			355,761
	Income per share ^{(a) (b)}:
	Basic		0.26			0.32			0.32			0.07			0.98
	Diluted		0.24			0.31			0.32			0.07			0.95



	Table:	18.1b
Unaudited quarterly financial data - prior year	2016:		Quarter									Full
	(in thousands, except per share data)		First		Second		Third		Fourth			Year
	Net premiums earned		$	221,341	$	231,456	$	237,376	$	235,053		$	925,226
	Investment income, net of expenses		27,809		27,248		27,515		28,094			110,666
	Realized gains (losses)		3,056		836		5,092		(52		)	8,932
	Other revenue		6,373		3,994		3,867		3,425			17,659
	Loss incurred, net		85,012		46,590		60,897		47,658			240,157
	Underwriting and other expenses, net		56,439		49,837		53,981		56,824			217,081
	Loss on debt extinguishment		13,440		1,868		75,223		—			90,531
	Provision for income tax		34,497		56,018		27,131		54,551			172,197
	Net income		69,191		109,221		56,618		107,487			342,517
	Income per share^{(a) (b)}:
	Basic		0.20		0.32		0.16		0.31			1.00
	Diluted		0.17		0.26		0.14		0.28			0.86


^(a)	Due to the use of weighted average shares outstanding when calculating earnings per share, the sum of the quarterly per share data may not equal the per share data for the year.


^(b)	In periods where convertible debt instruments are dilutive to earnings per share the “if-converted” method of computing diluted EPS requires an interest expense adjustment, net of tax, to net income available to shareholders. See Note 4 – “Earnings Per Share” for further discussion on our calculation of diluted EPS.

Significant Accounting Policies (Details)	3 Months Ended	12 Months Ended
Significant Accounting Policies (Details)	Dec. 31, 2017 USD ($)	Dec. 31, 2017 USD ($) Payment	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Home office and equipment [Abstract]
Accumulated depreciation of home office and equipment	$ 33,900,000	$ 33,900,000	$ 30,600,000	$ 26,100,000
Depreciation expense of home office and equipment		$ 5,400,000	4,600,000	3,200,000
Minimum number of payments past due to be in default \| Payment		2
Decrease in premium deficiency reserve		$ 0	0	23,751,000
Maximum age for qualified employees for both medical and dental benefits		65 years
Related party transaction amount		$ 0	$ 0	$ 0
Discrete tax benefits realized upon adoption of ASU		1,600,000
Accumulated other comprehensive loss
Home office and equipment [Abstract]
Cumulative effect to reclassify certain tax effects from accumulated other comprehensive loss	(10,400,000)	(10,422,000)
Retained earnings (deficit)
Home office and equipment [Abstract]
Cumulative effect to reclassify certain tax effects from accumulated other comprehensive loss	$ 10,400,000	$ 10,422,000
Minimum
Home office and equipment [Abstract]
Estimated useful life		3 years
Award vesting period		1 year
Maximum
Home office and equipment [Abstract]
Estimated useful life		45 years
Award vesting period		3 years

Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Basic earnings per share [Abstract]
Net income	$ 27,314	$ 120,027	$ 118,622	$ 89,798	$ 107,487	$ 56,618	$ 109,221	$ 69,191	$ 355,761	$ 342,517	$ 1,172,000
Weighted average common shares outstanding - basic (in shares)									362,380	342,890	339,552
Basic income per share (in dollars per share)	$ 0.07	$ 0.32	$ 0.32	$ 0.26	$ 0.31	$ 0.16	$ 0.32	$ 0.20	$ 0.98	$ 1.00	$ 3.45
Diluted earnings per share [Abstract]
Net income	$ 27,314	$ 120,027	$ 118,622	$ 89,798	$ 107,487	$ 56,618	$ 109,221	$ 69,191	$ 355,761	$ 342,517	$ 1,172,000
Diluted income available to common shareholders									$ 373,404	$ 370,883	$ 1,214,942
Weighted-average shares - Basic (in shares)									362,380	342,890	339,552
Effect of dilutive securities [Abstract]
Weighted-average shares - Diluted (in shares)									394,766	431,992	468,039
Diluted income per share (in dollars per share)	$ 0.07	$ 0.32	$ 0.31	$ 0.24	$ 0.28	$ 0.14	$ 0.26	$ 0.17	$ 0.95	$ 0.86	$ 2.60
Federal statutory income tax rate (in hundredths)									35.00%	35.00%	35.00%
2% Convertible Senior Notes due 2020
Diluted earnings per share [Abstract]
Dilutive securities									$ 907	$ 6,111	$ 7,928
Effect of dilutive securities [Abstract]
Dilutive securities (in shares)									8,317	54,450	71,917
Stated interest rate (in hundredths)	2.00%								2.00%
5% Convertible Senior Notes due 2017
Diluted earnings per share [Abstract]
Dilutive securities									$ 1,709	$ 6,362	$ 12,228
Effect of dilutive securities [Abstract]
Dilutive securities (in shares)									3,548	13,107	25,603
Stated interest rate (in hundredths)	5.00%								5.00%
9% Convertible Junior Subordinated Debentures due 2063
Diluted earnings per share [Abstract]
Dilutive securities									$ 15,027	$ 15,893	$ 22,786
Effect of dilutive securities [Abstract]
Dilutive securities (in shares)									19,028	20,075	28,854
Stated interest rate (in hundredths)	9.00%								9.00%
Unvested Restricted Stock Units
Effect of dilutive securities [Abstract]
Dilutive securities - Share based compensation (in shares)									1,493	1,470	2,113

Investments (Details) $ in Thousands	1 Months Ended	12 Months Ended
Investments (Details) $ in Thousands	Feb. 29, 2016	Dec. 31, 2017 USD ($) security	Dec. 31, 2016 USD ($) security
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Total at end of period		$ 4,946,278	$ 4,717,211
Total at end of period		4,983,315	4,685,222
Available-for-sale Equity Securities, Amortized Cost Basis [Abstract]
Fair Value		7,246	7,128
Total Investment Portfolio [Abstract]
Amortized Cost		4,953,501	4,724,355
Gross Unrealized Gains		68,623	28,628
Gross Unrealized Losses		(31,563)	(60,633)
Fair Value		4,990,561	4,692,350
Other than temporary impairments recorded in other comprehensive (loss) income		$ 0	0
Collateral, principal balance of FHLB (as a percent)	102.00%	102.00%
Collateral, principal balance of FHLB		$ 166,900
Assets held by insurance regulatory requirements		13,600	13,600
Maturities, Amortized Cost [Abstract]
Due in one year or less		541,755
Due after one year through five years		1,547,712
Due after five years through ten years		925,751
Due after ten years		1,335,170
Total debt securities with single maturity date		4,350,388
Total at end of period		4,946,278	4,717,211
Maturities, Fair Value [Abstract]
Due in one year or less		541,695
Due after one year through five years		1,544,943
Due after five years through ten years		929,883
Due after ten years		1,381,687
Total debt securities with single maturity date		4,398,208
Total at end of period		4,983,315	4,685,222
Continuous Unrealized Loss Portion, Fair Value [Abstract]
Less than 12 months		1,667,170	2,370,345
12 months or greater		752,693	294,916
Total investment portfolio		2,419,863	2,665,261
Continuous Unrealized Loss Portion, Unrealized Loses [Abstract]
Less than 12 months		(9,357)	(50,915)
12 months or greater		(22,206)	(9,718)
Total investment portfolio		$ (31,563)	$ (60,633)
Number of securities in unrealized loss position \| security		586	607
For securities in an unrealized loss position, percentage of fair value to amortized cost (in hundredths)		99.00%
For securities in an unrealized loss position, percentage backed by the U.S. Government (in hundredths)		27.00%
Total debt securities
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Total at end of period		$ 4,946,278	$ 4,717,211
Gross Unrealized Gains		68,584	28,620
Gross Unrealized Losses		(31,547)	(60,609)
Total at end of period		4,983,315	4,685,222
Total Investment Portfolio [Abstract]
Fair Value		4,983,315	4,685,222
Maturities, Amortized Cost [Abstract]
Total at end of period		4,946,278	4,717,211
Maturities, Fair Value [Abstract]
Total at end of period		4,983,315	4,685,222
U.S. Treasury securities and obligations of U.S. government corporations and agencies
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Total at end of period		179,850	73,847
Gross Unrealized Gains		274	407
Gross Unrealized Losses		(1,278)	(724)
Total at end of period		178,846	73,530
Total Investment Portfolio [Abstract]
Fair Value		178,846	73,530
Maturities, Amortized Cost [Abstract]
Total at end of period		179,850	73,847
Maturities, Fair Value [Abstract]
Total at end of period		178,846	73,530
Continuous Unrealized Loss Portion, Fair Value [Abstract]
Less than 12 months		144,042	48,642
12 months or greater		31,196	0
Total investment portfolio		175,238	48,642
Continuous Unrealized Loss Portion, Unrealized Loses [Abstract]
Less than 12 months		(796)	(724)
12 months or greater		(482)	0
Total investment portfolio		(1,278)	(724)
Obligations of U.S. states and political subdivisions
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Total at end of period		2,105,063	2,147,458
Gross Unrealized Gains		56,210	20,983
Gross Unrealized Losses		(8,749)	(25,425)
Total at end of period		2,152,524	2,143,016
Total Investment Portfolio [Abstract]
Fair Value		2,152,524	2,143,016
Maturities, Amortized Cost [Abstract]
Total at end of period		2,105,063	2,147,458
Maturities, Fair Value [Abstract]
Total at end of period		2,152,524	2,143,016
Continuous Unrealized Loss Portion, Fair Value [Abstract]
Less than 12 months		505,311	1,136,676
12 months or greater		211,684	13,681
Total investment portfolio		716,995	1,150,357
Continuous Unrealized Loss Portion, Unrealized Loses [Abstract]
Less than 12 months		(3,624)	(24,918)
12 months or greater		(5,125)	(507)
Total investment portfolio		(8,749)	(25,425)
Corporate debt securities
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Total at end of period		2,065,475	1,756,461
Gross Unrealized Gains		10,532	6,059
Gross Unrealized Losses		(9,169)	(18,610)
Total at end of period		2,066,838	1,743,910
Total Investment Portfolio [Abstract]
Fair Value		2,066,838	1,743,910
Maturities, Amortized Cost [Abstract]
Total at end of period		2,065,475	1,756,461
Maturities, Fair Value [Abstract]
Total at end of period		2,066,838	1,743,910
Continuous Unrealized Loss Portion, Fair Value [Abstract]
Less than 12 months		932,350	915,777
12 months or greater		200,716	35,769
Total investment portfolio		1,133,066	951,546
Continuous Unrealized Loss Portion, Unrealized Loses [Abstract]
Less than 12 months		(4,288)	(16,771)
12 months or greater		(4,881)	(1,839)
Total investment portfolio		(9,169)	(18,610)
ABS
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Total at end of period		4,925	59,519
Gross Unrealized Gains		0	74
Gross Unrealized Losses		(2)	(28)
Total at end of period		4,923	59,565
Total Investment Portfolio [Abstract]
Fair Value		4,923	59,565
Maturities, Amortized Cost [Abstract]
Debt securities without single maturity date		4,925
Total at end of period		4,925	59,519
Maturities, Fair Value [Abstract]
Debt securities without single maturity date		4,923
Total at end of period		4,923	59,565
Continuous Unrealized Loss Portion, Fair Value [Abstract]
Less than 12 months		4,923	3,366
12 months or greater		0	656
Total investment portfolio		4,923	4,022
Continuous Unrealized Loss Portion, Unrealized Loses [Abstract]
Less than 12 months		(2)	(28)
12 months or greater		0	0
Total investment portfolio		(2)	(28)
RMBS
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Total at end of period		189,153	231,733
Gross Unrealized Gains		60	102
Gross Unrealized Losses		(7,364)	(7,626)
Total at end of period		181,849	224,209
Total Investment Portfolio [Abstract]
Fair Value		181,849	224,209
Maturities, Amortized Cost [Abstract]
Debt securities without single maturity date		189,153
Total at end of period		189,153	231,733
Maturities, Fair Value [Abstract]
Debt securities without single maturity date		181,849
Total at end of period		181,849	224,209
Continuous Unrealized Loss Portion, Fair Value [Abstract]
Less than 12 months		14,979	46,493
12 months or greater		166,329	171,326
Total investment portfolio		181,308	217,819
Continuous Unrealized Loss Portion, Unrealized Loses [Abstract]
Less than 12 months		(280)	(857)
12 months or greater		(7,084)	(6,769)
Total investment portfolio		(7,364)	(7,626)
CMBS
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Total at end of period		301,014	327,042
Gross Unrealized Gains		1,204	769
Gross Unrealized Losses		(4,906)	(7,994)
Total at end of period		297,312	319,817
Total Investment Portfolio [Abstract]
Fair Value		297,312	319,817
Maturities, Amortized Cost [Abstract]
Debt securities without single maturity date		301,014
Total at end of period		301,014	327,042
Maturities, Fair Value [Abstract]
Debt securities without single maturity date		297,312
Total at end of period		297,312	319,817
Continuous Unrealized Loss Portion, Fair Value [Abstract]
Less than 12 months		51,096	205,545
12 months or greater		138,769	38,587
Total investment portfolio		189,865	244,132
Continuous Unrealized Loss Portion, Unrealized Loses [Abstract]
Less than 12 months		(358)	(7,529)
12 months or greater		(4,548)	(465)
Total investment portfolio		(4,906)	(7,994)
CLOs
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Total at end of period		100,798	121,151
Gross Unrealized Gains		304	226
Gross Unrealized Losses		(79)	(202)
Total at end of period		101,023	121,175
Total Investment Portfolio [Abstract]
Fair Value		101,023	121,175
Maturities, Amortized Cost [Abstract]
Debt securities without single maturity date		100,798
Total at end of period		100,798	121,151
Maturities, Fair Value [Abstract]
Debt securities without single maturity date		101,023
Total at end of period		101,023	121,175
Continuous Unrealized Loss Portion, Fair Value [Abstract]
Less than 12 months		14,243	13,278
12 months or greater		3,568	34,760
Total investment portfolio		17,811	48,038
Continuous Unrealized Loss Portion, Unrealized Loses [Abstract]
Less than 12 months		(7)	(73)
12 months or greater		(72)	(129)
Total investment portfolio		(79)	(202)
Equity securities
Available-for-sale Equity Securities, Amortized Cost Basis [Abstract]
Amortized Cost		7,223	7,144
Gross Unrealized Gains		39	8
Gross Unrealized Losses		(16)	(24)
Fair Value		7,246	7,128
Total Investment Portfolio [Abstract]
Fair Value		7,246	7,128
Continuous Unrealized Loss Portion, Fair Value [Abstract]
Less than 12 months		226	568
12 months or greater		431	137
Total investment portfolio		657	705
Continuous Unrealized Loss Portion, Unrealized Loses [Abstract]
Less than 12 months		(2)	(15)
12 months or greater		(14)	(9)
Total investment portfolio		$ (16)	$ (24)

Investments, Investment Income By Category (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income									$ 124,378	$ 113,882	$ 106,736
Investment expenses									(3,507)	(3,216)	(2,995)
Net investment income	$ 31,276	$ 30,402	$ 29,716	$ 29,477	$ 28,094	$ 27,515	$ 27,248	$ 27,809	120,871	110,666	103,741
Fixed income
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income									122,105	112,513	105,882
Equity securities
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income									206	182	208
Cash equivalents
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income									1,447	754	191
Other
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income									$ 620	$ 433	$ 455

Investments, Gain (Loss) on Investments (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Gain (Loss) on Investments [Line Items]
Recognized other than temporary impairments									$ 0	$ 0	$ 0
Realized gains (losses)	$ 460,000	$ (47,000)	$ (42,000)	$ (122,000)	$ (52,000)	$ 5,092,000	$ 836,000	$ 3,056,000	249,000	8,932,000	28,361,000
Change in unrealized gains (losses)									69,052,000	(5,425,000)	(33,718,000)
Gross realized gains, gross realized losses and impairment losses [Abstract]
Gross realized gains									1,599,000	11,909,000	30,039,000
Gross realized losses									(1,350,000)	(2,977,000)	(1,678,000)
Net realized investment gains	$ 460,000	$ (47,000)	$ (42,000)	$ (122,000)	$ (52,000)	$ 5,092,000	$ 836,000	$ 3,056,000	249,000	8,932,000	28,361,000
Available-for-Sale Securities
Gain (Loss) on Investments [Line Items]
Realized gains (losses)									249,000	8,932,000	28,361,000
Gross realized gains, gross realized losses and impairment losses [Abstract]
Net realized investment gains									249,000	8,932,000	28,361,000
Available-for-Sale Securities \| Fixed income
Gain (Loss) on Investments [Line Items]
Realized gains (losses)									228,000	5,310,000	28,335,000
Change in unrealized gains (losses)									69,026,000	(5,403,000)	(33,687,000)
Gross realized gains, gross realized losses and impairment losses [Abstract]
Net realized investment gains									228,000	5,310,000	28,335,000
Available-for-Sale Securities \| Equity Securities
Gain (Loss) on Investments [Line Items]
Realized gains (losses)									21,000	3,622,000	26,000
Change in unrealized gains (losses)									39,000	(36,000)	(32,000)
Gross realized gains, gross realized losses and impairment losses [Abstract]
Net realized investment gains									21,000	3,622,000	26,000
Available-for-Sale Securities \| Other
Gain (Loss) on Investments [Line Items]
Realized gains (losses)									0	0	0
Change in unrealized gains (losses)									(13,000)	14,000	1,000
Gross realized gains, gross realized losses and impairment losses [Abstract]
Net realized investment gains									$ 0	$ 0	$ 0

Fair Value Measurements - Unobservable Input Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Total Investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	$ 4,959	$ 4,083	$ 2,167
Total realized/unrealized gains (losses) [Abstract]
Included in earnings and reported as net realized investment gains		3,579
Included in earnings and reported as losses incurred, net	0	0	0
Purchases	0	4,258	2,541
Sales	(420)	(6,961)	(625)
Balance at end of period	4,539	4,959	4,083
Total debt securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	691	1,228	1,846
Total realized/unrealized gains (losses) [Abstract]
Included in earnings and reported as net realized investment gains		0
Included in earnings and reported as losses incurred, net	0	0	0
Purchases	0	0	7
Sales	(420)	(537)	(625)
Balance at end of period	271	691	1,228
Equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	4,268	2,855	321
Total realized/unrealized gains (losses) [Abstract]
Included in earnings and reported as net realized investment gains		3,579
Included in earnings and reported as losses incurred, net	0	0	0
Purchases	0	4,258	2,534
Sales	0	(6,424)	0
Balance at end of period	4,268	4,268	2,855
Real Estate Acquired
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	11,748	12,149	12,658
Total realized/unrealized gains (losses) [Abstract]
Included in earnings and reported as net realized investment gains		0
Included in earnings and reported as losses incurred, net	(1,315)	(1,142)	(2,322)
Purchases	34,749	36,859	34,624
Sales	(32,469)	(36,118)	(32,811)
Balance at end of period	$ 12,713	$ 11,748	$ 12,149

Fair Value Measurements - Liabilities Not Measured at Fair Value (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
5% Convertible Senior Notes due 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Stated interest rate (in hundredths)	5.00%
2% Convertible Senior Notes due 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Stated interest rate (in hundredths)	2.00%
Senior Notes \| 5.75% Senior Notes due 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Stated interest rate (in hundredths)	5.75%
9% Convertible Junior Subordinated Debentures due 2063
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Stated interest rate (in hundredths)	9.00%
Carrying Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
FHLB Advance	$ 155,000	$ 155,000
5% Notes	0	144,789
2% Notes	0	204,672
5.75% Notes	418,560	417,406
9% Debentures	256,872	256,872
Total financial liabilities	830,432	1,178,739
Fair Value \| Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
FHLB Advance	152,124	151,905
5% Notes	0	147,679
2% Notes	0	308,605
5.75% Notes	465,473	445,987
9% Debentures	353,507	323,040
Total financial liabilities	$ 971,104	$ 1,377,216

Debt Summary of Obligations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Long-term debt, gross	$ 836.9	$ 1,189.5
Deferred issuance costs	(6.5)	(10.8)
Total long-term debt	830.4	1,178.7
Interest payments made	57.8	49.5
Federal Home Loan Bank Advances (FHLB)
Debt Instrument [Line Items]
Long-term debt, gross	155.0	155.0
Interest payments made	3.0	2.4
5% Convertible Senior Notes due 2017
Debt Instrument [Line Items]
Long-term debt, gross	$ 0.0	145.0
Stated interest rate (in hundredths)	5.00%
Interest payments made	$ 3.6	10.6
2% Convertible Senior Notes due 2020
Debt Instrument [Line Items]
Long-term debt, gross	$ 0.0	207.6
Stated interest rate (in hundredths)	2.00%
Interest payments made	$ 2.1	9.1
Senior Notes \| 5.75% Senior Notes due 2023
Debt Instrument [Line Items]
Long-term debt, gross	$ 425.0	425.0
Stated interest rate (in hundredths)	5.75%
Interest payments made	$ 25.1	0.0
Convertible Junior Subordinated Debentures, at 9% per annum, Due 2063
Debt Instrument [Line Items]
Long-term debt, gross	$ 256.9	256.9
Stated interest rate (in hundredths)	9.00%
Interest payments made	$ 23.1	27.4
Line of Credit
Debt Instrument [Line Items]
Interest payments made	$ 0.9	$ 0.0

Debt (Details)		1 Months Ended			3 Months Ended								12 Months Ended
Debt (Details)	May 01, 2017 USD ($)	Apr. 30, 2017 USD ($) shares	Aug. 31, 2016 USD ($)	Feb. 29, 2016 USD ($)	Dec. 31, 2017 USD ($) Period $ / shares shares	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($) shares	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2017 USD ($) Period $ / shares shares	Dec. 31, 2016 USD ($) shares	Dec. 31, 2015 USD ($)	Mar. 21, 2017 USD ($)	Feb. 26, 2016 USD ($)
Debt Instrument [Line Items]
Loss on debt extinguishment					$ 0	$ 0	$ 65,000	$ 0	$ 0	$ 75,223,000	$ 1,868,000	$ 13,440,000	$ 65,000	$ 90,531,000	$ 507,000
Repayments of Convertible Debt													$ 145,620,000	363,778,000	11,152,000
FHLBC advances																	$ 155,000,000
FHLBC fixed interest rate				1.91%
Collateral, principal balance of FHLB (as a percent)				102.00%									102.00%
Long-term debt, gross					$ 836,900,000				1,189,500,000				$ 836,900,000	1,189,500,000
Repayment of long-term debt													$ 0	0	$ 61,953,000
2% Convertible Senior Notes due 2020
Debt Instrument [Line Items]
Stated interest rate (in hundredths)					2.00%								2.00%
Principal amount of notes converted into shares		$ 202,500,000
Principal amount of notes redeemed for cash		$ 5,100,000
Conversion rate (in shares per $1,000 note) \| shares													143.8332
Principal amount of notes used in determining conversion rate					$ 1,000								$ 1,000
Shares issued during period upon conversion of convertible debt (in shares) \| shares		29,100,000
Loss on debt extinguishment		$ 70,000												$ 74,300,000
Extinguishment of debt, amount										292,400,000
Repayments of long-term debt										362,100,000
Repayments of Convertible Debt										$ 230,700,000
Repayments of debt (in shares) \| shares										18,300,000				18,300,000
Reduction in shares for computation of earnings per share \| shares										42,100,000
Long-term debt, gross					$ 0				207,600,000				$ 0	$ 207,600,000
Line of Credit \| Revolving Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity																$ 175,000,000
Revolving credit facility								$ 150,000,000
5% Convertible Senior Notes due 2017
Debt Instrument [Line Items]
Stated interest rate (in hundredths)					5.00%								5.00%
Loss on debt extinguishment														7,900,000
Extinguishment of debt, amount														188,500,000
Repayments of Convertible Debt	$ 145,000,000													$ 195,500,000
Reduction in shares for computation of earnings per share \| shares														14,000,000
Long-term debt, gross					$ 0				145,000,000				$ 0	$ 145,000,000
Senior Notes \| 5.75% Senior Notes due 2023
Debt Instrument [Line Items]
Stated interest rate (in hundredths)					5.75%								5.75%
Outstanding principal amount			$ 425,000,000
Proceeds from issuance of debt			418,100,000
Redemption price, percentage (in hundredths)													100.00%
Other expenses associated with the issuance of notes			$ 1,200,000
Ownership percentage threshold for declaration of due and payable													25.00%
Long-term debt, gross					$ 425,000,000				425,000,000				$ 425,000,000	425,000,000
Senior Notes \| 5.75% Senior Notes due 2023 \| U.S. Treasury Rate
Debt Instrument [Line Items]
Basis spread on redemption premium (as a percent)													0.50%
Convertible Junior Subordinated Debentures, at 9% per annum, Due 2063
Debt Instrument [Line Items]
Stated interest rate (in hundredths)					9.00%								9.00%
Conversion rate (in shares per $1,000 note) \| shares													74.0741
Principal amount of notes used in determining conversion rate					$ 1,000								$ 1,000
Loss on debt extinguishment														8,300,000
Extinguishment of debt, amount				$ 132,700,000
Reduction in shares for computation of earnings per share \| shares													9,800,000
Redemption price, percentage (in hundredths)													100.00%
Long-term debt, gross					$ 256,900,000				$ 256,900,000				$ 256,900,000	256,900,000
Repayment of long-term debt				$ 150,700,000
Reacquisition of convertible junior subordinated debentures-equity component														$ 6,300,000
Initial conversion price (in dollars per share) \| $ / shares					$ 13.50								$ 13.50
Period preceding election to convert													5 days
Convertible debt, number of equity instruments reserved for conversion \| shares					19,000,000								19,000,000
Closing sale price of our common stock for consideration of redemption (in dollars per share) \| $ / shares					$ 17.55								$ 17.55
Minimum number of trading days													20 days
Maximum number of trading days													30 days
Minimum number of consecutive interest periods for which interest payments may be deferred \| Period					1								1
Maximum period for which interest payments may be deferred without giving rise to an event of default													10 years
Period in which reasonable commercial efforts must begin, maximum													1 day
Anniversary payment release of the start of the interest deferral to the Alternative Payment Mechanism in lieu of the final maturity of the debentures													10 years
Net proceeds cap (in hundredths)					2.00%								2.00%
Maximum number of shares of common stock issuable under the Alternative Payment Mechanism (in shares) \| shares					10,000,000								10,000,000
Maximum percentage of aggregate principal amount of the debentures (in hundredths)					25.00%								25.00%

Loss Reserves - Narrative (Details) $ in Thousands	12 Months Ended
Loss Reserves - Narrative (Details) $ in Thousands	Dec. 31, 2017 USD ($) loan	Dec. 31, 2016 USD ($) loan	Dec. 31, 2015 USD ($) loan
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Premium refund liability, expected claim payments	$ 61,000	$ 85,000
Other items removed from inventory \| loan	1,337	1,273	1,121
Losses for unpaid claims and adjustment expense	$ 493,300	$ 689,258	$ 823,058
Percent of inventory in default for more than 36 consecutive months	45.00%	47.00%	50.00%
Pool insurance notice inventory (in number of loans) \| loan	1,309	1,883	2,739
Settlements for commutations of coverage, pools of nonperforming loans
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Losses for unpaid claims and adjustment expense	$ 54,000
Settlements for commutations of coverage, pools of nonperforming loans, and claims paying practices
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Losses for unpaid claims and adjustment expense		$ 53,000
Payments for settlements
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Losses for unpaid claims and adjustment expense			$ 10,000
Payments for settlements \| Freddie Mac
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Losses for unpaid claims and adjustment expense		$ 42,000	$ 42,000
Decrease in estimated claim rate on primary delinquencies
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Percentage of prior year default inventory resolved (in hundredths)	67.00%	63.00%	60.00%

Loss Reserves - Reconciliation of Changes in Loss Reserves (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Loss Reserve [Roll Forward]
Reserve at beginning of year	$ 1,438,813	$ 1,893,402	$ 2,396,807
Less reinsurance recoverable	48,474	50,493	44,487	$ 57,841
Net reserve at beginning of year	937,161	1,388,320	1,848,915	$ 2,338,966
Losses incurred: [Abstract]
Current year	284,913	387,815	453,849
Prior years	(231,204)	(147,658)	(110,302)
Total losses incurred	53,709	240,157	343,547
Losses paid [Abstract]
Current year	11,267	14,823	25,980
Prior years	493,300	689,258	823,058
Reinsurance terminations	301	(3,329)	(15,440)
Total losses paid	504,868	700,752	833,598
Reserve at end of year	$ 985,635	$ 1,438,813	$ 1,893,402

Loss Reserves - Prior Year Loss Reserves (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior years	$ (231,204)	$ (147,658)	$ (110,302)
Decrease in estimated claim rate on primary delinquencies
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior years	(248,000)	(148,000)	(141,000)
Increase in estimated severity on primary delinquencies
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior years	9,000	9,000	43,000
Change in estimates related to pool reserves, LAE reserves, reinsurance and other
Liability for Claims and Claims Adjustment Expense [Line Items]
Prior years	$ 8,000	$ (9,000)	$ (12,000)

Loss Reserves - Default Inventory Reconciliation (Details) - loan	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Primary Default Inventory [Roll Forward]
Delinquent inventory at beginning of year	50,282	62,633	79,901
New Notices	68,268	67,434	74,315
Cures	(61,094)	(65,516)	(73,610)
Paids (including those charged to a deductible or captive)	(9,206)	(12,367)	(16,004)
Rescissions and denials	(357)	(629)	(848)
Other items removed from inventory	(1,337)	(1,273)	(1,121)
Delinquent inventory at end of year	46,556	50,282	62,633

Loss Reserves - Aging of Primary Default Inventory and Number of Delinquent Payments (Details) - loan	3 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Liability for Claims and Claims Adjustment Expense [Abstract]
Default notices for loans in IADAs	9,294	1,968
Primary Default Inventory In FEMA Individual Assistance Disaster Areas	12,446	7,162
Aging of the Primary Default Inventory [Abstract]
3 months or less	17,119	12,194	13,053
3 months or less (in hundredths)	37.00%	24.00%	21.00%
4 - 11 months	12,050	13,450	15,763
4 - 11 months (in hundredths)	26.00%	27.00%	25.00%
12 months or more	17,387	24,638	33,817
12 months or more (in hundredths)	37.00%	49.00%	54.00%
Total primary default inventory	46,556	50,282	62,633	79,901
Total primary default inventory (in hundredths)	100.00%	100.00%	100.00%
Primary claims received inventory included in ending default inventory	954	1,385	2,769
Primary claims received inventory included in ending default inventory (in hundredths)	2.00%	3.00%	4.00%
Number of Payments Delinquent [Abstract]
3 payments or less	21,678	18,419	20,360
3 payments or less (in hundredths)	46.00%	36.00%	33.00%
4 - 11 payments	12,446	12,892	15,092
4 - 11 payments (in hundredths)	27.00%	26.00%	24.00%
12 payments or more	12,432	18,971	27,181
12 payments or more (in hundredths)	27.00%	38.00%	43.00%
Total primary default inventory	46,556	50,282	62,633	79,901
Total primary default inventory (in hundredths)	100.00%	100.00%	100.00%

Reinsurance - Summary of Reinsurance Agreements (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Premiums Earned, Net [Abstract]
Premiums earned, direct									$ 1,059,973	$ 1,058,545	$ 997,892
Premiums earned, assumed									509	662	1,178
Premiums earned, ceded									(125,735)	(133,981)	(102,848)
Net premiums earned	$ 237,425	$ 237,083	$ 231,136	$ 229,103	$ 235,053	$ 237,376	$ 231,456	$ 221,341	934,747	925,226	896,222
Policyholder Benefits and Claims Incurred, Net [Abstract]
Losses incurred, direct									74,727	273,207	369,680
Losses incurred, assumed									183	1,138	1,552
Losses incurred, ceded									(21,201)	(34,188)	(27,685)
Net losses incurred	$ (30,996)	$ 29,747	$ 27,339	$ 27,619	$ 47,658	$ 60,897	$ 46,590	$ 85,012	53,709	240,157	343,547
Ceded premiums written, net of profit commission									125,726	133,885	55,391
Ceded premiums earned, net of profit commission (1)									125,735	133,981	102,848
Ceded losses incurred									21,201	34,188	27,685
Quota Share Reinsurance Agreements, Excluding Captives
Premiums Earned, Net [Abstract]
Premiums earned, ceded									(120,974)	(125,460)	(88,587)
Policyholder Benefits and Claims Incurred, Net [Abstract]
Losses incurred, ceded									(22,336)	(30,201)	(17,484)
Ceded premiums written, net of profit commission									120,974	125,460	41,233
Ceded premiums earned, net of profit commission (1)									120,974	125,460	88,587
Ceded losses incurred									22,336	30,201	17,484
Ceding commissions									49,321	47,629	30,816
Profit commission									$ 125,629	$ 112,685	$ 112,847

Reinsurance - Narrative (Details) - USD ($)		3 Months Ended		12 Months Ended
Reinsurance - Narrative (Details) - USD ($)	Jul. 01, 2015	Mar. 31, 2018	Sep. 30, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Effects of Reinsurance [Line Items]
Ceded premiums written, net of profit commission				$ 125,726,000	$ 133,885,000	$ 55,391,000
Ceded to Other Companies				125,735,000	133,981,000	102,848,000
Reinsurance recoverable on loss reserves				$ 48,474,000	$ 50,493,000	44,487,000	$ 57,841,000
Period of existing captive reinsurance agreement				10 years	10 years
Fair value of trust fund assets under our captive agreements				$ 80,000,000	$ 91,000,000
Quota Share Reinsurance Agreement, 2017
Effects of Reinsurance [Line Items]
Contingent termination fee				$ 0
Threshold for private mortgage insurer eligibility requirements for termination election				90.00%
Quota share, percentage				30.00%
Ceding commission, percentage				20.00%
Loss ratio				60.00%
Quota Share Reinsurance Agreement, 2015
Effects of Reinsurance [Line Items]
Contingent termination fee				$ 0
Threshold for private mortgage insurer eligibility requirements for termination election				90.00%
Quota share, percentage				30.00%
Ceding commission, percentage				20.00%
Loss ratio				60.00%
Quota Share Reinsurance Agreement, 2013
Effects of Reinsurance [Line Items]
Ceded premiums written, net of profit commission			$ 69,400,000
Ceded to Other Companies			11,600,000
Ceding commissions			$ 11,600,000
Profit commission	$ 142,500,000
Quota Share Reinsurance Agreement, 2018 \| Forecast
Effects of Reinsurance [Line Items]
Contingent termination fee		$ 0
Threshold for private mortgage insurer eligibility requirements for termination election		90.00%
Quota share, percentage		30.00%
Ceding commission, percentage		20.00%
Loss ratio		54.00%
Quota Share Reinsurance Agreements, Excluding Captives
Effects of Reinsurance [Line Items]
Ceded premiums written, net of profit commission				$ 120,974,000	125,460,000	41,233,000
Ceded to Other Companies				120,974,000	125,460,000	88,587,000
Ceding commissions				49,321,000	47,629,000	30,816,000
Profit commission				125,629,000	112,685,000	$ 112,847,000
Reinsurance recoverable on loss reserves				39,300,000	31,800,000
Reinsurance Agreements, Captive Agreements
Effects of Reinsurance [Line Items]
Reinsurance recoverable on loss reserves				$ 9,000,000	$ 19,000,000

Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Components of Other Comprehensive Income (Loss) [Abstract]
Net unrealized investment gains (losses) arising during the year									$ 69,052	$ (5,425)	$ (33,718)
Income tax (expense) benefit									(21,505)	1,776	11,738
Valuation allowance									0	0	62,383
Net of taxes									47,547	(3,649)	40,403
Net changes in benefit plan assets and obligations									(8,983)	(14,799)	(12,818)
Income tax benefit									3,144	5,179	4,487
Valuation allowance									0	0	(7,383)
Net of taxes									(5,839)	(9,620)	(15,714)
Net changes in unrealized foreign currency translation adjustment									45	(1,463)	(5,699)
Income tax (expense) benefit									(14)	512	2,000
Valuation allowance									0	0	(529)
Net of taxes									31	(951)	(4,228)
Total other comprehensive income (loss)									60,114	(21,687)	(52,235)
Total income tax (expense) benefit, net of valuation allowance									(18,375)	7,467	72,696
Other comprehensive income (loss), net of tax									41,739	(14,220)	20,461
Amounts Reclassified From Accumulated Other Comprehensive Income [Abstract]
Total reclassifications									784,496	514,714	487,687
Total income tax benefit (expense), net of valuation allowance	$ (218,142)	$ (64,440)	$ (61,994)	$ (84,159)	$ (54,551)	$ (27,131)	$ (56,018)	$ (34,497)	(428,735)	(172,197)	684,313
Valuation allowance											161,158
Net income	27,314	$ 120,027	$ 118,622	89,798	107,487	$ 56,618	$ 109,221	69,191	355,761	342,517	1,172,000
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of year				2,548,842				2,236,140	2,548,842	2,236,140
Balance, end of year	3,154,526				2,548,842				3,154,526	2,548,842	2,236,140
Accumulated other comprehensive loss
Components of Other Comprehensive Income (Loss) [Abstract]
Other comprehensive income (loss), net of tax									41,739	(14,220)	20,461
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of year				(75,100)				(60,880)	(75,100)	(60,880)	(81,341)
Other comprehensive income (loss) before reclassifications									40,651	(8,147)	33,707
Less: Amounts reclassified from AOCL									(1,088)	6,073	13,246
Less: Amounts reclassified for lower enacted corporate tax rate	10,400								10,422
Balance, end of year	(43,783)				(75,100)				(43,783)	(75,100)	(60,880)
Net unrealized gains and losses on available-for-sale securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of year				(20,797)				(17,148)	(20,797)	(17,148)	(57,551)
Other comprehensive income (loss) before reclassifications									45,870	508	51,655
Less: Amounts reclassified from AOCL									(1,677)	4,157	11,252
Less: Amounts reclassified for lower enacted corporate tax rate									(2,525)
Balance, end of year	29,275				(20,797)				29,275	(20,797)	(17,148)
Net benefit plan assets and obligations recognized in shareholders' equity
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of year				(54,272)				(44,652)	(54,272)	(44,652)	(28,938)
Other comprehensive income (loss) before reclassifications									(5,250)	(8,658)	(13,720)
Less: Amounts reclassified from AOCL									589	962	1,994
Less: Amounts reclassified for lower enacted corporate tax rate									12,947
Balance, end of year	(73,058)				(54,272)				(73,058)	(54,272)	(44,652)
Net unrealized foreign currency translation
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of year				$ (31)				$ 920	(31)	920	5,148
Other comprehensive income (loss) before reclassifications									31	3	(4,228)
Less: Amounts reclassified from AOCL									0	954	0
Less: Amounts reclassified for lower enacted corporate tax rate									0
Balance, end of year	$ 0				$ (31)				0	(31)	920
Reclassification from Accumulated Other Comprehensive Income
Amounts Reclassified From Accumulated Other Comprehensive Income [Abstract]
Total reclassifications									(1,674)	9,154	13,877
Total income tax benefit (expense), net of valuation allowance									586	(3,081)	(631)
Net income									(1,088)	6,073	13,246
Reclassification from Accumulated Other Comprehensive Income \| Net unrealized gains and losses on available-for-sale securities
Amounts Reclassified From Accumulated Other Comprehensive Income [Abstract]
Total reclassifications									(2,580)	6,207	11,693
Total income tax benefit (expense), net of valuation allowance									903	(2,050)	(4,076)
Valuation allowance									0	0	3,635
Net income									(1,677)	4,157	11,252
Reclassification from Accumulated Other Comprehensive Income \| Net benefit plan assets and obligations recognized in shareholders' equity
Amounts Reclassified From Accumulated Other Comprehensive Income [Abstract]
Total reclassifications									906	1,480	2,184
Total income tax benefit (expense), net of valuation allowance									(317)	(518)	(764)
Valuation allowance									0	0	574
Net income									589	962	1,994
Reclassification from Accumulated Other Comprehensive Income \| Net unrealized foreign currency translation
Amounts Reclassified From Accumulated Other Comprehensive Income [Abstract]
Total reclassifications									0	1,467	0
Total income tax benefit (expense), net of valuation allowance									0	(513)	0
Net income									$ 0	$ 954	$ 0

Benefit Plans - Components of Net Periodic Benefit Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Pension and Supplemental Executive Retirement Plans
Defined Benefit Plan Disclosure [Line Items]
Company Service Cost	$ 9,556	$ 9,130	$ 10,256
Interest Cost	15,475	15,906	15,847
Expected Return on Assets	(20,099)	(19,508)	(21,109)
Other Adjustments	0	0	0
Subtotal	4,932	5,528	4,994
Amortization of Net Transition Obligation/(Asset)	0	0	0
Amortization of Net Prior Service Cost/(Credit)	(426)	(687)	(845)
Amortization of Net Losses/(Gains)	6,169	5,856	5,485
Total Amortization	5,743	5,169	4,640
Net Periodic Benefit Cost	10,675	10,697	9,634
Cost of settlements	0	1,277	3,172
Total Expense for Year	10,675	11,974	12,806
Other Postretirement Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Company Service Cost	813	751	833
Interest Cost	706	704	697
Expected Return on Assets	(5,248)	(4,886)	(4,991)
Other Adjustments	0	0	0
Subtotal	(3,729)	(3,431)	(3,461)
Amortization of Net Transition Obligation/(Asset)	0	0	0
Amortization of Net Prior Service Cost/(Credit)	(6,649)	(6,649)	(6,649)
Amortization of Net Losses/(Gains)	0	0	(175)
Total Amortization	(6,649)	(6,649)	(6,824)
Net Periodic Benefit Cost	(10,378)	(10,080)	(10,285)
Cost of settlements	0	0	0
Total Expense for Year	$ (10,378)	$ (10,080)	$ (10,285)

Benefit Plans - Development of Funded Status (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Pension and Supplemental Executive Retirement Plans
Defined Benefit Plan Disclosure [Line Items]
Accumulated Benefit Obligation	$ 411,996	$ 360,423
Projected Benefit Obligation	(417,770)	(369,808)	$ (349,483)
Plan Assets at Fair Value	401,142	360,900	350,107
Funded Status - Overfunded/(Underfunded)	(16,628)	(8,908)
Other Postretirement Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Accumulated Benefit Obligation	24,716	17,378
Projected Benefit Obligation	(24,716)	(17,378)	(16,423)
Plan Assets at Fair Value	85,303	70,408	$ 65,568
Funded Status - Overfunded/(Underfunded)	$ 60,587	$ 53,030

Benefit Plans - Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Pension and Supplemental Executive Retirement Plans
Defined Benefit Plan Disclosure [Line Items]
Net Actuarial (Gain)/Loss	$ 109,904	$ 103,861
Net Prior Service Cost/(Credit)	(1,850)	(2,286)
Net Transition Obligation/(Asset)	0	0
Total at Year End	108,054	101,575	$ 92,647
Other Postretirement Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Net Actuarial (Gain)/Loss	(10,234)	(6,088)
Net Prior Service Cost/(Credit)	(5,342)	(11,991)
Net Transition Obligation/(Asset)	0	0
Total at Year End	$ (15,576)	$ (18,079)	$ (23,951)

Benefit Plans - Change in Project Benefit/Accumulated Benefit Obligations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Pension and Supplemental Executive Retirement Plans
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit Obligation at Beginning of Year	$ 369,808	$ 349,483
Company Service Cost	9,556	9,130	$ 10,256
Interest Cost	15,475	15,906	15,847
Plan Participants' Contributions	0	0
Net Actuarial (Gain)/Loss due to Assumption Changes	38,496	14,450
Net Actuarial (Gain)/Loss due to Plan Experience	2,338	5,428
Benefit Payments from Fund	(17,578)	(21,831)
Benefit Payments Directly by Company	(335)	(2,669)
Plan Amendments	10	16
Other Adjustment	0	(105)
Benefit Obligation at End of Year	417,770	369,808	349,483
Other Postretirement Benefit Plan
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit Obligation at Beginning of Year	17,378	16,423
Company Service Cost	813	751	833
Interest Cost	706	704	697
Plan Participants' Contributions	395	408
Net Actuarial (Gain)/Loss due to Assumption Changes	5,981	497
Net Actuarial (Gain)/Loss due to Plan Experience	924	357
Benefit Payments from Fund	(1,404)	(1,678)
Benefit Payments Directly by Company	0	0
Plan Amendments	0	0
Other Adjustment	(77)	(84)
Benefit Obligation at End of Year	$ 24,716	$ 17,378	$ 16,423

Benefit Plans - Change in Plan Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Pension and Supplemental Executive Retirement Plans
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair Value of Plan Assets at Beginning of Year	$ 360,900	$ 350,107
Company Contributions	9,435	11,369
Plan Participants' Contributions	0	0
Benefit Payments from Fund	(17,578)	(21,831)
Benefit Payments paid directly by Company	(335)	(2,669)
Actual Return on Assets	48,720	23,924
Other Adjustment	0	0
Fair Value of Plan Assets at End of Year	401,142	360,900
Other Postretirement Benefit Plan
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair Value of Plan Assets at Beginning of Year	70,408	65,568
Company Contributions	0	0
Plan Participants' Contributions	395	408
Benefit Payments from Fund	(1,404)	(1,678)
Benefit Payments paid directly by Company	0	0
Actual Return on Assets	16,299	6,518
Other Adjustment	(395)	(408)
Fair Value of Plan Assets at End of Year	$ 85,303	$ 70,408

Benefit Plans - Change in Accumulated Other Comprehensive Income (AOCI) and Expected Amortization (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Pension and Supplemental Executive Retirement Plans
AOCI Attributable to Parent, Net of Tax [Roll Forward]
AOCI in Prior Year	$ 101,575	$ 92,647
Recognized during year - Prior Service (Cost)/Credit	426	687
Recognized during year - Net Actuarial (Losses)/Gains	(6,169)	(5,856)
Occurring during year - Prior Service Cost	10	16
Occurring during year - Net Actuarial Losses/(Gains)	12,212	15,358
Occurring during year - Net Settlement Losses/(Gains)	0	(1,277)
Other adjustments	0	0
AOCI in Current Year	108,054	101,575
Amortization of Net Transition Obligation/(Asset)	0
Amortization of Prior Service Cost/(Credit)	(349)
Amortization of Net Losses/(Gains)	7,140
Other Postretirement Benefit Plan
AOCI Attributable to Parent, Net of Tax [Roll Forward]
AOCI in Prior Year	(18,079)	(23,951)
Recognized during year - Prior Service (Cost)/Credit	6,649	6,649
Recognized during year - Net Actuarial (Losses)/Gains	0	0
Occurring during year - Prior Service Cost	0	0
Occurring during year - Net Actuarial Losses/(Gains)	(4,146)	(777)
Occurring during year - Net Settlement Losses/(Gains)	0	0
Other adjustments	0	0
AOCI in Current Year	(15,576)	$ (18,079)
Amortization of Net Transition Obligation/(Asset)	0
Amortization of Prior Service Cost/(Credit)	(4,104)
Amortization of Net Losses/(Gains)	$ (183)

Benefit Plans - Actuarial Assumptions and Year-End Asset Allocations (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Pension and Supplemental Executive Retirement Plans
Defined Benefit Plan Disclosure [Line Items]
Discount Rate (in hundredths)	3.75%	4.30%
Rate of Compensation Increase (in hundredths)	3.00%	3.00%
Discount Rate (in hundredths)	4.30%	4.65%
Expected Long-term Return on Plan Assets (in hundredths)	5.75%	5.75%
Rate of Compensation Increase (in hundredths)	3.00%	3.00%
Other Postretirement Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Discount Rate (in hundredths)	3.55%	3.95%
Discount Rate (in hundredths)	3.95%	4.30%
Expected Long-term Return on Plan Assets (in hundredths)	7.50%	7.50%
Health Care Cost Trend Rate Assumed for Next Year (in hundredths)	6.50%	6.50%
Rate to Which the Cost Trend Rate is Assumed to Decline (Ultimate Trend Rate) (in hundredths)	5.00%	5.00%
Year That the Rate Reaches the Ultimate Trend Rate	2024	2020
Weighted-average asset allocations of plans (in hundredths)	100.00%	100.00%
Other Postretirement Benefit Plan \| Equity securities
Defined Benefit Plan Disclosure [Line Items]
Weighted-average asset allocations of plans (in hundredths)	100.00%	100.00%
Other Postretirement Benefit Plan \| Total debt securities
Defined Benefit Plan Disclosure [Line Items]
Weighted-average asset allocations of plans (in hundredths)	0.00%	0.00%
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Weighted-average asset allocations of plans (in hundredths)	100.00%	100.00%
Pension Plan \| Equity securities
Defined Benefit Plan Disclosure [Line Items]
Weighted-average asset allocations of plans (in hundredths)	21.00%	23.00%
Pension Plan \| Total debt securities
Defined Benefit Plan Disclosure [Line Items]
Weighted-average asset allocations of plans (in hundredths)	79.00%	77.00%

Benefit Plans - Additional Disclosures (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Other Postretirement Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Company Contributions	$ 0	$ 0
Current plus 1	0
Actual Benefit Payments for the Year Ending: Current	1,086
Expected Benefit Payments for the Year Ending: Current plus 1	1,174
Expected Benefit Payments for the Year Ending: Current plus 2	1,368
Expected Benefit Payments for the Year Ending: Current plus 3	1,689
Expected Benefit Payments for the Year Ending: Current plus 4	1,944
Expected Benefit Payments for the Year Ending: Current plus 5	2,044
Expected Benefit Payments for the Year Ending: Current plus 6 - 10	11,914
Effect of 1-percentage point increase on total service and interest cost component	252
Effect of 1-percentage point decrease on total service and interest cost components	(217)
Effect of 1-percentage point increase on postretirement benefit obligation	3,093
Effect of 1-percentage point decrease on postretirement benefit obligation	$ (2,748)
Other Postretirement Benefit Plan \| Equity securities \| Minimum
Defined Benefit Plan Disclosure [Line Items]
Target asset allocations (in hundredths)	70.00%
Other Postretirement Benefit Plan \| Equity securities \| Maximum
Defined Benefit Plan Disclosure [Line Items]
Target asset allocations (in hundredths)	100.00%
Other Postretirement Benefit Plan \| Real Estate \| Minimum
Defined Benefit Plan Disclosure [Line Items]
Target asset allocations (in hundredths)	0.00%
Other Postretirement Benefit Plan \| Real Estate \| Maximum
Defined Benefit Plan Disclosure [Line Items]
Target asset allocations (in hundredths)	15.00%
Other Postretirement Benefit Plan \| Commodities \| Minimum
Defined Benefit Plan Disclosure [Line Items]
Target asset allocations (in hundredths)	0.00%
Other Postretirement Benefit Plan \| Commodities \| Maximum
Defined Benefit Plan Disclosure [Line Items]
Target asset allocations (in hundredths)	10.00%
Other Postretirement Benefit Plan \| Fixed Income/Cash \| Minimum
Defined Benefit Plan Disclosure [Line Items]
Target asset allocations (in hundredths)	0.00%
Other Postretirement Benefit Plan \| Fixed Income/Cash \| Maximum
Defined Benefit Plan Disclosure [Line Items]
Target asset allocations (in hundredths)	10.00%
Pension and Supplemental Executive Retirement Plans
Defined Benefit Plan Disclosure [Line Items]
Company Contributions	$ 9,435	$ 11,369
Current plus 1	10,950
Actual Benefit Payments for the Year Ending: Current	17,913
Expected Benefit Payments for the Year Ending: Current plus 1	28,639
Expected Benefit Payments for the Year Ending: Current plus 2	33,127
Expected Benefit Payments for the Year Ending: Current plus 3	29,669
Expected Benefit Payments for the Year Ending: Current plus 4	31,085
Expected Benefit Payments for the Year Ending: Current plus 5	31,899
Expected Benefit Payments for the Year Ending: Current plus 6 - 10	$ 151,512

Benefit Plans - Narrative (Details) - USD ($)	12 Months Ended
Benefit Plans - Narrative (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Minimum percentages of gain loss consider for amortization (in hundredths)	10.00%
Minimum value of outstanding noncallable bonds used in hypothetical cash flow bond matching exercise	$ 50,000,000
Future earnings period used in determining the expected average rate of earnings	20 years
Minimum percentage return should exceed growth in consumer price index annually (in hundredths)	5.75%
Maximum investment in international mutual funds (in hundredths)	30.00%
Percent of international mutual funds equity allocation in emerging markets (in hundredths)	3.00%
Percent of international mutual funds equity allocation in companies primarily based in Europe and the Pacific Basin (in hundredths)	21.00%
Discretionary profit sharing contribution as a percentage of participant's eligible compensation (in hundredths)	5.00%
Matching contribution rate on employees' before-tax contributions, first contribution level (in hundredths)	80.00%
Employee contributions subject to employer match, first contribution level	$ 1,000
Matching contribution rate on employees' before-tax contributions, second contribution level (in hundredths)	40.00%
Employee contributions subject to employer match, second contribution level	$ 2,000
Matching contribution rate on employees' before-tax contributions, hired after 01/01/2014 (in hundredths)	100.00%
Employee contributions subject to employer match for employees hired after 01/01/2014 (in hundredths)	4.00%
Profit sharing and 401(k) savings plan expenses	$ 6,000,000	$ 5,900,000	$ 5,100,000
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Lump sum pension plan benefit payments	$ 6,300,000	$ 11,200,000
Pension Plan \| Equity securities \| Maximum
Defined Benefit Plan Disclosure [Line Items]
Target asset allocations (in hundredths)	40.00%
Other Postretirement Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Health care trend rate used for current year (in hundredths)	6.50%
Health Care Cost Trend Rate Assumed for Next Year (in hundredths)	6.50%	6.50%
Rate to Which the Cost Trend Rate is Assumed to Decline (Ultimate Trend Rate) (in hundredths)	5.00%	5.00%
Other Postretirement Benefit Plan \| Equity securities \| Maximum
Defined Benefit Plan Disclosure [Line Items]
Target asset allocations (in hundredths)	100.00%

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
Income Taxes (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2007	Dec. 31, 2017	Dec. 31, 2016
Net deferred tax assets and liabilities [Abstract]
Total deferred tax assets													$ 258,663	$ 636,449
Total deferred tax liabilities													(24,282)	(28,794)
Net deferred tax asset													234,381	607,655
Components of net deferred tax asset [Abstract]
Unearned premium reserves													29,196	40,153
Benefit plans													(7,162)	(12,350)
Federal net operating loss													155,839	520,812
Loss reserves													4,994	10,883
Unrealized (appreciation) depreciation in investments													(7,782)	11,211
Mortgage investments													8,963	17,751
Deferred compensation													7,265	12,517
AMT credit carryforward													37,017	2,215
Other, net													6,051	4,463
Tax provision (benefit) [Abstract]
Provision for income taxes before valuation allowance											$ 163,497
Change in valuation allowance											(161,158)
Reversal of the valuation allowance											(686,652)
Provision for (benefit from) income taxes	$ 218,142	$ 64,440	$ 61,994	$ 84,159	$ 54,551	$ 27,131	$ 56,018	$ 34,497	$ 428,735	$ 172,197	(684,313)
Change in deferred tax valuation allowance, included in other comprehensive income											(54,500)
Net operating loss carryforwards, regular tax basis													742,000
Components of provisions for (benefit from) income taxes [Abstract]
Current Federal									73,348	9,470	8,067
Deferred Federal									351,677	160,657	(686,652)
Other									3,710	2,070	(5,728)
Provision for (benefit from) income taxes	218,142	$ 64,440	$ 61,994	84,159	54,551	$ 27,131	$ 56,018	34,497	428,735	172,197	(684,313)
Income tax expense due to remeasurement of net deferred tax assets									133,000
Income taxes paid									$ 22,000	$ 4,500	$ 5,400
Reconciliation of effective income tax rate [Abstract]
Federal statutory income tax rate (in hundredths)									35.00%	35.00%	35.00%
Additional income tax provision related to the rate decrease included in the Tax Act									17.00%	0.00%	0.00%
Additional income tax provision related to IRS litigation (in hundredths)									3.70%	0.10%	0.10%
Valuation allowance (in hundredths)									0.00%	0.00%	(173.80%)
Tax exempt municipal bond interest (in hundredths)									(1.40%)	(1.90%)	(0.80%)
Other, net (in hundredths)									0.40%	0.30%	(0.80%)
Effective income tax provision (benefit) rate (in hundredths)									54.70%	33.50%	(140.30%)
Information regarding income tax examinations [Abstract]
Amount of IRS assessment for unpaid taxes and penalties related to REMIC issue													197,500
Estimate of federal interest that may be due													205,000
Amount of payment made related to the IRS assessment on the REMIC issue												$ 65,200
Amount of IRS assessment for unpaid taxes and penalties related to disallowance of carryback of 2009 net operating loss													261,400
Estimate of additional state income taxes and interest that may be due													85,800
Unrecognized tax benefits	142,821			108,245	108,245			107,120	$ 108,245	$ 107,120	$ 106,230		142,821	108,245
Provision for additional taxes and interest									29,000
Unrecognized tax benefits [Roll Forward]
Balance at beginning of year				$ 108,245				$ 107,120	108,245	107,120	106,230
Additions based on tax positions related to the current year									0	0	0
Additions for tax positions of prior years									35,003	1,125	890
Reductions for tax positions of prior years									(427)	0	0
Settlements									0	0	0
Balance at end of year	$ 142,821				$ 108,245				142,821	$ 108,245	107,120
Unrecognized tax benefits [Abstract]
Total amount of unrecognized tax benefits that would affect effective tax rate													129,300
Interest expense recognized during period									$ 23,100
Unrecognized tax benefits, accrued interest													52,000	$ 28,900
Significant change in unrecognized tax benefits													142,800
Approximate net cash outflows upon resolution of IRS matters													$ 55,000
Deferred Tax Asset, Changes In Current Period
Tax provision (benefit) [Abstract]
Change in valuation allowance											154,800
Deferred Tax Asset, Changes In Current Period \| Other Comprehensive Income (Loss)
Tax provision (benefit) [Abstract]
Change in valuation allowance											(6,300)
Deferred Tax Asset, Changes In Current Period \| Income Tax Expense (Benefit)
Tax provision (benefit) [Abstract]
Change in valuation allowance											161,100
Deferred Tax Asset, Changes In Future Periods
Tax provision (benefit) [Abstract]
Change in valuation allowance											747,500
Deferred Tax Asset, Changes In Future Periods \| Other Comprehensive Income (Loss)
Tax provision (benefit) [Abstract]
Change in valuation allowance											60,800
Deferred Tax Asset, Changes In Future Periods \| Income Tax Expense (Benefit)
Tax provision (benefit) [Abstract]
Change in valuation allowance											$ 686,700

Income Taxes - Summary of Changes In Tax Provisions (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2015 USD ($)
Movement In Deferred Tax Asset [Roll Forward]
Balance at December 31, 2014	$ 902,300
Valuation allowance	161,158
Balance at December 31, 2015	0
Deferred Tax Asset, Changes In Current Period
Movement In Deferred Tax Asset [Roll Forward]
Valuation allowance	(154,800)
Deferred Tax Asset, Changes In Current Period \| Other Comprehensive Income (Loss)
Movement In Deferred Tax Asset [Roll Forward]
Valuation allowance	6,300
Deferred Tax Asset, Changes In Current Period \| Income Tax Expense (Benefit)
Movement In Deferred Tax Asset [Roll Forward]
Valuation allowance	(161,100)
Deferred Tax Asset, Changes In Future Periods
Movement In Deferred Tax Asset [Roll Forward]
Valuation allowance	(747,500)
Deferred Tax Asset, Changes In Future Periods \| Other Comprehensive Income (Loss)
Movement In Deferred Tax Asset [Roll Forward]
Valuation allowance	(60,800)
Deferred Tax Asset, Changes In Future Periods \| Income Tax Expense (Benefit)
Movement In Deferred Tax Asset [Roll Forward]
Valuation allowance	$ (686,700)

Shareholders' Equity (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended		12 Months Ended
	Apr. 30, 2017	Dec. 31, 2017	Sep. 30, 2016	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Shares repurchased, weighted average price per share					$ 8.03
Shares repurchased, value					$ 147,100
Shareholder rights accompanying each outstanding share of the company's common stock (in number of Rights)		1		1
Common stock, beneficial ownership threshold to be considered an Acquiring Person (in hundredths)		5.00%		5.00%
Purchase price (in dollars per share)		$ 45		$ 45
Purchase price (in dollars per one-tenth share)		4.50		4.50
Redemption price (in dollars per Right)		$ 0.001		$ 0.001
Rights
Debt Instrument [Line Items]
Period after person becomes acquiring person				10 days
Common stock purchased per right		0.1		0.1
2% Convertible Senior Notes due 2020
Debt Instrument [Line Items]
Principal amount of notes converted into shares	$ 202,500
Shares issued during period upon conversion of convertible debt (in shares)	29,100,000
Treasury stock reissued during period upon conversion of notes (in shares)	18,700,000
Stock issued during period upon conversion of notes, new issues (in shares)	10,400,000
Repayments of debt (in shares)			18,300,000		18,300,000
Stated interest rate (in hundredths)		2.00%		2.00%
Convertible Junior Subordinated Debentures, at 9% per annum, Due 2063
Debt Instrument [Line Items]
Stated interest rate (in hundredths)		9.00%		9.00%
Reacquisition of convertible junior subordinated debentures-equity component					$ 6,300
Accumulated other comprehensive loss
Debt Instrument [Line Items]
Cumulative effect to reclassify certain tax effects from accumulated other comprehensive loss		$ (10,400)		$ (10,422)
Retained earnings (deficit)
Debt Instrument [Line Items]
Cumulative effect to reclassify certain tax effects from accumulated other comprehensive loss		$ 10,400		$ 10,422

Statutory Information (Details)	12 Months Ended
Statutory Information (Details)	Dec. 31, 2017 USD ($) jurisdiction	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Statutory Capital [Abstract]
Percentage of premiums earned required to be maintained as contingency loss reserves (in hundredths)	50.00%
Period that contingency loss reserves must be held (in years)	10 years
Percentage of net premiums earned that incurred losses must exceed to enable early withdrawals from contingency loss reserves (in hundredths)	35.00%
Related Party Transaction [Line Items]
Statutory net income (loss)	$ 310,776,000	$ 106,326,000	$ (72,767,000)
Statutory policyholders' surplus	1,622,115,000	1,506,475,000	1,608,214,000
Contingency reserve	$ 1,896,701,000	1,360,088,000	826,706,000
Statutory capital requirements [Abstract]
Number of jurisdictions with risk-to-capital requirements \| jurisdiction	16
Maximum permitted risk-to-capital ratio commonly applied	25 to 1
Risk-to-capital ratio on a combined basis at end of period	10.5 to 1
Risk-to-capital ratio on combined insurance operations	10.5
Percentage of statutory policyholders surplus used to determine maximum allowable dividends	10.00%
Maximum
Statutory capital requirements [Abstract]
Risk to capital ratio	25
Other Insurance Subsidiaries
Related Party Transaction [Line Items]
Dividends paid to the parent company			6,500,000
Distributions from other insurance subsidiaries to the parent company	$ 0	52,001,000	38,500,000
Mortgage Guaranty Insurance Corporation
Related Party Transaction [Line Items]
Loss ratio	5.00%
Additions to the surplus of MGIC from parent company funds	$ 0	36,025,000	0
Dividends paid to the parent company	$ 140,000,000	$ 64,000,000	$ 0
Statutory capital requirements [Abstract]
Risk to capital ratio	9.5
Risk to capital ratio at end of period	9.5 to 1
Amount of policyholders position above or below required MPP	$ 2,100,000,000
Amount of required MPP	$ 1,200,000,000
Adjusted statutory net income measurement period	3 years
Adjusted statutory net income dividend payment measurement period	2 years
Adjustment to statutory net income	$ 473,000,000

Share-based Compensation Plans (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost	$ 14.9	$ 11.4	$ 11.9
Income tax benefit from compensation cost	$ 5.2	$ 4.0	$ 4.2
Shares [Roll Forward]
Restricted stock outstanding at end of period (in shares)	3,300,000
Restricted Stock/Restricted Stock Units
Weighted average grant date fair market value [Abstract]
Restricted stock outstanding at end of period (in dollars per share)	$ 7.44
Granted (in dollars per share)	10.41	$ 5.66	$ 9.03
Vested (in dollars per share)	7.71
Forfeited (in dollars per share)	8.43
Restricted stock outstanding at end of period (in dollars per share)	$ 8.78	$ 7.44
Shares [Roll Forward]
Restricted stock outstanding at beginning of period (in shares)	3,146,672
Granted (in shares)	1,631,744
Vested (in shares)	(1,409,347)
Forfeited (in shares)	(68,460)
Restricted stock outstanding at end of period (in shares)	3,300,609	3,146,672
Additional disclosures [Abstract]
Restricted stock, performance shares (in shares)	2,500,000
Restricted stock, time vested shares (in shares)	800,000
Total fair value of restricted stock vested	$ 15.3	$ 12.2	$ 17.2
Unrecognized compensation cost	13.2
Unrecognized compensation cost, performance shares	9.9
Unrecognized compensation cost, time vested shares	$ 3.3
Weighted-average period for recognition of compensation cost	1 year 6 months
2015 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum number of shares can be awarded under the plan (in shares)	10,000,000
Additional disclosures [Abstract]
Shares available for future grants (in shares)	6,700,000
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	1 year
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years

Leases (Details) - USD ($) $ in Thousands	12 Months Ended
Leases (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Leases [Abstract]
Remaining term of operating leases (in years)	5 years
Minimum future operating lease payments [Abstract]
2018	$ 808
2019	823
2020	583
2021	48
2022 and thereafter	0
Total	2,262
Total rental expense under operating leases	$ 2,000	$ 2,100	$ 2,200

Unaudited Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Net premiums earned	$ 237,425	$ 237,083	$ 231,136	$ 229,103	$ 235,053	$ 237,376	$ 231,456	$ 221,341	$ 934,747	$ 925,226	$ 896,222
Investment income, net of expenses	31,276	30,402	29,716	29,477	28,094	27,515	27,248	27,809	120,871	110,666	103,741
Realized gains (losses)	460	(47)	(42)	(122)	(52)	5,092	836	3,056	249	8,932	28,361
Other revenue	2,341	2,922	2,502	2,422	3,425	3,867	3,994	6,373	10,187	17,659	12,964
Loss incurred, net	(30,996)	29,747	27,339	27,619	47,658	60,897	46,590	85,012	53,709	240,157	343,547
Underwriting and other expenses, net	57,042	56,146	55,292	59,304	56,824	53,981	49,837	56,439	227,784	217,081
Loss on debt extinguishment	0	0	65	0	0	75,223	1,868	13,440	65	90,531	507
Provision for income tax	218,142	64,440	61,994	84,159	54,551	27,131	56,018	34,497	428,735	172,197	(684,313)
Net income	$ 27,314	$ 120,027	$ 118,622	$ 89,798	$ 107,487	$ 56,618	$ 109,221	$ 69,191	$ 355,761	$ 342,517	$ 1,172,000
Earnings per Share [Abstract]
Basic (in dollars per share)	$ 0.07	$ 0.32	$ 0.32	$ 0.26	$ 0.31	$ 0.16	$ 0.32	$ 0.20	$ 0.98	$ 1.00	$ 3.45
Diluted (in dollars per share)	$ 0.07	$ 0.32	$ 0.31	$ 0.24	$ 0.28	$ 0.14	$ 0.26	$ 0.17	$ 0.95	$ 0.86	$ 2.60

SCHEDULE I - SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES (Details) $ in Thousands	Dec. 31, 2017 USD ($)
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Amortized Cost	$ 4,953,501
Fair Value	4,990,561
Amount at which shown in the balance sheet	4,990,561
Fixed income
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Amortized Cost	4,946,278
Fair Value	4,983,315
Amount at which shown in the balance sheet	4,983,315
Fixed income \| U.S. Treasury securities and obligations of U.S. government corporations and agencies
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Amortized Cost	179,850
Fair Value	178,846
Amount at which shown in the balance sheet	178,846
Fixed income \| Obligations of U.S. states and political subdivisions
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Amortized Cost	2,105,063
Fair Value	2,152,524
Amount at which shown in the balance sheet	2,152,524
Fixed income \| Public utilities
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Amortized Cost	222,619
Fair Value	222,806
Amount at which shown in the balance sheet	222,806
Fixed income \| ABS
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Amortized Cost	4,925
Fair Value	4,923
Amount at which shown in the balance sheet	4,923
Fixed income \| Collateralized loan obligations
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Amortized Cost	100,798
Fair Value	101,023
Amount at which shown in the balance sheet	101,023
Fixed income \| Mortgage-backed
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Amortized Cost	490,167
Fair Value	479,161
Amount at which shown in the balance sheet	479,161
Fixed income \| All other corporate bonds
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Amortized Cost	1,842,856
Fair Value	1,844,032
Amount at which shown in the balance sheet	1,844,032
Equity Securities
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Amortized Cost	7,223
Fair Value	7,246
Amount at which shown in the balance sheet	7,246
Equity Securities \| Industrial, miscellaneous and all other
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]
Amortized Cost	7,223
Fair Value	7,246
Amount at which shown in the balance sheet	$ 7,246

SCHEDULE II - CONDENSED FINANCIAL INFORMATION OF REGISTRANT (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Assets
Fixed income (amortized cost, 2017 – $195,846; 2016 – $247,396)												$ 4,983,315	$ 4,685,222
Cash and cash equivalents	$ 99,851			$ 155,410	$ 155,410			$ 181,120	$ 155,410	$ 181,120	$ 197,882	99,851	155,410	$ 181,120
Accrued investment income												46,060	44,073
Other assets												78,478	73,345
Total assets												5,619,499	5,734,529
Liabilities:
Senior notes												418,560	417,406
Convertible senior notes												0	349,461
Convertible junior subordinated debentures												256,872	256,872
Total liabilities												2,464,973	3,185,687
Shareholders’ equity:
Common stock (one dollar par value, shares authorized 1,000,000; shares issued 2017 - 370,567; 2016 - 359,400; outstanding 2017 - 370,567; 2016 - 340,663)												370,567	359,400
Paid-in capital												1,850,582	1,782,337
Treasury stock (shares at cost 2016 – 18,737)												0	(150,359)
Accumulated other comprehensive loss, net of tax												(43,783)	(75,100)
Retained earnings												977,160	632,564
Total shareholders' equity												3,154,526	2,548,842	2,236,140
Total liabilities and shareholders' equity												5,619,499	5,734,529
Parenthetical information [Abstract]
Fixed income, amortized cost												$ 4,946,278	$ 4,717,211
Common stock, par value (in dollars per share)												$ 1	$ 1
Common stock, shares authorized (in shares)												1,000,000,000	1,000,000,000
Common stock, shares issued (in shares)												370,567,000	359,400,000
Common stock, shares outstanding (in shares)												370,567,000	340,663,000
Treasury stock, shares at cost (in shares)												0	18,737,000
Revenues:
Investment income, net of expenses	31,276	$ 30,402	$ 29,716	29,477	28,094	$ 27,515	$ 27,248	27,809	120,871	110,666	103,741
Realized gains (losses)	460	(47)	(42)	(122)	(52)	5,092	836	3,056	249	8,932	28,361
Total revenues									1,066,054	1,062,483	1,041,288
Expenses:
Interest expense									57,035	56,672	68,932
Loss on debt extinguishment	0	0	65	0	0	75,223	1,868	13,440	65	90,531	507
Total losses and expenses									281,558	547,769	553,601
Income before tax									784,496	514,714	487,687
Provision for (benefit from) income taxes	218,142	64,440	61,994	84,159	54,551	27,131	56,018	34,497	428,735	172,197	(684,313)
Net income	27,314	120,027	118,622	89,798	107,487	56,618	109,221	69,191	355,761	342,517	1,172,000
Other comprehensive income (loss), net of tax									41,739	(14,220)	20,461
Comprehensive income									397,500	328,297	1,192,461
Cash flows from operating activities:
Net income	27,314	120,027	118,622	89,798	107,487	56,618	109,221	69,191	355,761	342,517	1,172,000
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Deferred Federal									351,677	160,657	(686,652)
Loss on debt extinguishment	0	$ 0	$ 65	0	0	$ 75,223	$ 1,868	13,440	65	90,531	507
Change in certain assets and liabilities:
Accrued investment income									(1,987)	(3,849)	(9,706)
Net cash provided by operating activities									406,657	224,760	161,395
Cash flows from investing activities:
Purchase of fixed income									(1,293,616)	(1,360,386)	(2,462,844)
Sale of fixed income									246,908	728,042	1,796,153
Net cash used in investing activities									(303,641)	(93,392)	(96,958)
Cash flows from financing activities:
Proceeds from revolving credit facility									150,000	0	0
Repayment of revolving credit facility									(150,000)	0	0
Proceeds from issuance of long-term debt									0	573,094	0
Repayment of long-term debt									0	0	(61,953)
Purchase or repayment of convertible senior notes									(145,620)	(363,778)	(11,152)
Repurchase of common stock									0	(147,127)	0
Payment of debt issuance costs									(1,630)	(1,127)	0
Payment of withholding taxes related to share-based compensation net share settlement									(6,821)	(5,030)	(7,242)
Net cash used in financing activities									(158,575)	(157,078)	(81,199)
Net decrease in cash and cash equivalents									(55,559)	(25,710)	(16,762)
Cash and cash equivalents at beginning of year				155,410				181,120	155,410	181,120	197,882
Cash and cash equivalents at end of year	99,851				155,410				99,851	155,410	181,120
Parent Company
Assets
Fixed income (amortized cost, 2017 – $195,846; 2016 – $247,396)												$ 194,061	$ 245,435
Cash and cash equivalents	22,247			37,666	37,666			19,417	37,666	19,417	10,507	22,247	37,666	$ 19,417
Investment in subsidiaries, at equity in net assets												3,567,034	3,150,671
Accounts receivable - affiliates												1,414	780
Income taxes - current and deferred												192,570	289,703
Accrued investment income												1,941	1,749
Other assets												1,275	80
Total assets												3,980,542	3,726,084
Liabilities:
Senior notes												418,560	417,406
Convertible senior notes												0	349,461
Convertible junior subordinated debentures												389,522	389,522
Accrued interest												17,934	20,853
Total liabilities												826,016	1,177,242
Shareholders’ equity:
Common stock (one dollar par value, shares authorized 1,000,000; shares issued 2017 - 370,567; 2016 - 359,400; outstanding 2017 - 370,567; 2016 - 340,663)												370,567	359,400
Paid-in capital												1,850,582	1,782,337
Treasury stock (shares at cost 2016 – 18,737)												0	(150,359)
Accumulated other comprehensive loss, net of tax												(43,783)	(75,100)
Retained earnings												977,160	632,564
Total shareholders' equity												3,154,526	2,548,842
Total liabilities and shareholders' equity												3,980,542	3,726,084
Parenthetical information [Abstract]
Fixed income, amortized cost												$ 195,846	$ 247,396
Common stock, par value (in dollars per share)												$ 1	$ 1
Common stock, shares authorized (in shares)												1,000,000,000	1,000,000,000
Common stock, shares issued (in shares)												370,567,000	359,400,000
Common stock, shares outstanding (in shares)												370,567,000	340,663,000
Treasury stock, shares at cost (in shares)												0	18,737,000
Revenues:
Investment income, net of expenses									3,177	3,807	7,586
Realized gains (losses)									(13)	646	357
Total revenues									3,164	4,453	7,943
Expenses:
Operating expenses									642	1,409	582
Interest expense									65,972	64,598	68,932
Loss on debt extinguishment									65	82,234	507
Total losses and expenses									66,679	148,241	70,021
Income before tax									(63,515)	(143,788)	(62,078)
Provision for (benefit from) income taxes									95,517	(52,575)	(125,487)
Equity in net income of subsidiaries									514,793	433,730	1,108,591
Net income									355,761	342,517	1,172,000
Other comprehensive income (loss), net of tax									41,739	(14,220)	20,461
Comprehensive income									397,500	328,297	1,192,461
Cash flows from operating activities:
Net income									355,761	342,517	1,172,000
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Equity in net income of subsidiaries									(514,793)	(433,730)	(1,108,591)
Dividends received from subsidiaries									110,145	64,000	6,500
Deferred Federal									96,741	(55,988)	(125,532)
Loss on debt extinguishment									65	82,234	507
Other									18,716	16,722	31,701
Change in certain assets and liabilities:
Accounts receivable - affiliates									(634)	158	(626)
Income taxes receivable									297	3,602	(8,308)
Accrued investment income									(192)	1,951	(265)
Accrued interest									(2,819)	6,811	(652)
Net cash provided by operating activities									63,287	28,277	(33,266)
Cash flows from investing activities:
Capital distributions from subsidiaries									0	51,987	32,000
Capital contributions to subsidiaries									0	(36,025)	0
Purchase of fixed income									(97,091)	(194,751)	(295,010)
Sale of fixed income									176,960	330,142	386,385
Net cash used in investing activities									79,869	151,353	123,375
Cash flows from financing activities:
Proceeds from revolving credit facility									150,000	0	0
Repayment of revolving credit facility									(150,000)	0	0
Proceeds from issuance of long-term debt									0	418,094	0
Repayment of long-term debt									0	0	(61,953)
Purchase or repayment of convertible senior notes									(150,124)	(426,191)	(12,004)
Repurchase of common stock									0	(147,127)	0
Payment of debt issuance costs									(1,630)	(1,127)	0
Payment of withholding taxes related to share-based compensation net share settlement									(6,821)	(5,030)	(7,242)
Net cash used in financing activities									(158,575)	(161,381)	(81,199)
Net decrease in cash and cash equivalents									(15,419)	18,249	8,910
Cash and cash equivalents at beginning of year				$ 37,666				$ 19,417	37,666	19,417	10,507
Cash and cash equivalents at end of year	$ 22,247				$ 37,666				$ 22,247	$ 37,666	$ 19,417

SCHEDULE II - CONDENSED FINANCIAL INFORMATION OF REGISTRANT - SUPPLEMENTARY NOTES (Details) - USD ($)	1 Months Ended	12 Months Ended
	Feb. 29, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Supplementary Insurance Information, by Segment [Line Items]
Percentage of statutory policyholders surplus used to determine maximum allowable dividends		10.00%
Convertible junior subordinated debentures		$ 256,872,000	$ 256,872,000
Other Insurance Subsidiaries
Supplementary Insurance Information, by Segment [Line Items]
Dividends paid to the parent company				$ 6,500,000
Distributions from other insurance subsidiaries to the parent company		0	52,001,000	38,500,000
Proceeds from contribution from parent		0		0
Parent Company
Supplementary Insurance Information, by Segment [Line Items]
Convertible junior subordinated debentures		$ 389,522,000	389,522,000
Mortgage Guaranty Insurance Corporation
Supplementary Insurance Information, by Segment [Line Items]
Adjusted statutory net income measurement period		3 years
Adjusted statutory net income dividend payment measurement period		2 years
Dividends paid to the parent company		$ 140,000,000	64,000,000	0
Additions to the surplus of MGIC from parent company funds		$ 0	$ 36,025,000	$ 0
Convertible Junior Subordinated Debentures, at 9% per annum, Due 2063
Supplementary Insurance Information, by Segment [Line Items]
Stated interest rate (in hundredths)		9.00%
Extinguishment of debt, amount	$ 132,700,000

SCHEDULE IV - REINSURANCE (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Supplemental Schedule of Reinsurance Premiums for Insurance Companies [Abstract]
Gross Amount	$ 1,059,973	$ 1,058,545	$ 997,892
Ceded to Other Companies	125,735	133,981	102,848
Assumed From Other Companies	509	662	1,178
Net Amount	$ 934,747	$ 925,226	$ 896,222
Percentage of Amount Assumed to Net	0.10%	0.10%	0.10%

Nature of Business (Details) $ in Billions	Dec. 31, 2017 USD ($)
Nature of Business [Abstract]
Direct domestic primary insurance in force	$ 194.9
Direct domestic primary risk in force	$ 50.3

Litigation and Contingencies (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
Average paid claim reduction due to curtailments (in hundredths)	5.60%	5.50%
Maximum exposure to loss	$ 285

Fair Value Measurements (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	$ 4,990,561	$ 4,692,350
Real estate acquired	12,713	11,748
Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	84,576	33,550
Real estate acquired	0	0
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	4,901,446	4,653,841
Real estate acquired	0	0
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	4,539	4,959
Real estate acquired	12,713	11,748
Total debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	4,983,315	4,685,222
Total debt securities \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	81,598	30,690
Total debt securities \| Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	4,901,446	4,653,841
Total debt securities \| Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	271	691
U.S. Treasury securities and obligations of U.S. government corporations and agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	178,846	73,530
U.S. Treasury securities and obligations of U.S. government corporations and agencies \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	81,598	30,690
U.S. Treasury securities and obligations of U.S. government corporations and agencies \| Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	97,248	42,840
U.S. Treasury securities and obligations of U.S. government corporations and agencies \| Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	0	0
Obligations of U.S. states and political subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	2,152,524	2,143,016
Obligations of U.S. states and political subdivisions \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	0	0
Obligations of U.S. states and political subdivisions \| Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	2,152,253	2,142,325
Obligations of U.S. states and political subdivisions \| Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	271	691
Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	2,066,838	1,743,910
Corporate debt securities \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	0	0
Corporate debt securities \| Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	2,066,838	1,743,910
Corporate debt securities \| Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	0	0
ABS
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	4,923	59,565
ABS \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	0	0
ABS \| Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	4,923	59,565
ABS \| Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	0	0
RMBS
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	181,849	224,209
RMBS \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	0	0
RMBS \| Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	181,849	224,209
RMBS \| Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	0	0
CMBS
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	297,312	319,817
CMBS \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	0	0
CMBS \| Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	297,312	319,817
CMBS \| Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	0	0
CLOs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	101,023	121,175
CLOs \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	0	0
CLOs \| Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	101,023	121,175
CLOs \| Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	0	0
Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	7,246	7,128
Equity securities \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	2,978	2,860
Equity securities \| Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	0	0
Equity securities \| Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total investments	$ 4,268	$ 4,268