Nature of Business [Abstract] Nature of Business [Abstract] Due after five years through ten years Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, after Year 5 Through 10 Loss reserves Liability for Claims and Claims Adjustment Expense, Property Casualty Liability Net unrealized gains and losses on available-for-sale securities AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent [Member] Litigation and Contingencies Legal Matters and Contingencies [Text Block] Net Actuarial (Gain)/Loss Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss) Vested (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period Changes in fair value of plan assets and other comprehensive income (loss) Schedule Of Changes In Fair Value Of Plan Assets and Other Comprehensive Income (Loss) [Table Text Block] Schedule Of Changes In Fair Value Of Plan Assets and Other Comprehensive Income (Loss) Consolidated Entities [Axis] Consolidated Entities [Axis] Remaining Excess of Loss Reinsurance Coverage Reinsurance Retention Policy, Remaining Excess Of Loss Reinsurance Coverages Reinsurance Retention Policy, Remaining Excess of Loss Reinsurance Coverages Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] Security Exchange Name Security Exchange Name Premiums earned, direct Gross Amount Direct Premiums Earned Noncatastrophic Event [Domain] Noncatastrophic Event [Domain] Equity securities, at fair value (cost, 2021 - $15,838; 2020 - $17,522) Equity Securities, FV-NI, Current SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Table] SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Table] Conversion price (in dollars per share) Debt Instrument, Convertible, Conversion Price Forfeited (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value Benefit plans adjustment Net of taxes Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax and Reclassification Adjustment, Attributable to Parent 2020 QSR, Two Year Quota Share Reinsurance Agreement, 2020, Two Year [Member] Quota Share Reinsurance Agreement, 2020, Two Year Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Shares available for future grants (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant Beginning delinquent inventory Ending delinquent inventory Total primary default inventory Primary Default Inventory The number of loans in the primary default inventory. 12 months or more Primary Default Inventory, Twelve Months or More The number of loans that have been in the primary default inventory for twelve months or more as of the balance sheet date. Schedule of Gain (Loss) on Securities [Table] Schedule of Gain (Loss) on Securities [Table] Reclassification out of accumulated other comprehensive income Reclassification out of Accumulated Other Comprehensive Income [Table Text Block] Ceded premiums written and earned, net of profit commission Ceded Premiums Written and Earned, Net of Profit Commission Ceded Premiums Written and Earned, Net of Profit Commission Minimum value of outstanding noncallable bonds used in hypothetical cash flow bond matching exercise Defined Benefit Plan, Minimum value of outstanding noncallable bonds used in hypothetical cash flow bond matching exercise The minimum value of outstanding noncallable bonds used in a hypothetical cash flow bond matching exercise for purposes of selecting a discount rate related to actuarial assumptions used in the valuation of projected benefit obligations, net periodic benefit costs and accumulated postretirement benefit obligation. Risk-to-capital ratio on combined insurance operations Statutory Capital Requirements, Risk To Capital Ratio For Combined Insurance Operations Statutory Capital Requirements, Risk To Capital Ratio For Combined Insurance Operations Subsequent Event Type [Domain] Subsequent Event Type [Domain] Direct domestic primary insurance in force Direct Domestic Primary Insurance In Force The principal balance in a Company's records of all mortgage loans it insures. Remaining authorized repurchase amount Stock Repurchase Program, Remaining Authorized Repurchase Amount Total fixed income securities Defined Benefit Plan, Debt Security [Member] Proceeds from issuance of debt Proceeds from Issuance of Senior Long-term Debt Maximum percentage of aggregate principal amount of the debentures (in hundredths) Maximum percentage of aggregate principal amount of the debentures The maximum ratio of total net proceeds of all issuances of qualifying securities to the aggregate principal amount of the debentures. Pursuant to the Alternative Payment Mechanism under the note agreement(s), the entity may not issue qualifying preferred stock if the total net proceeds exceed this ratio. Restricted Cash and Cash Equivalents Cash and Cash Equivalents, Restricted Cash and Cash Equivalents, Policy [Policy Text Block] Increase in credit allowance for the period Debt Securities, Available-for-sale, Allowance for Credit Loss, Period Increase (Decrease) Accrued interest Increase (Decrease) in Interest Payable, Net Included in earnings and reported as losses incurred, net Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings Award Type [Domain] Award Type [Domain] Collateral pledged for FHLB advance Federal Home Loan Bank, Advances, General Debt Obligations, Disclosures, Collateral Pledged Local Phone Number Local Phone Number Amortized cost, gross unrealized gains and losses and fair value of investment portfolio Schedule of Available-for-sale Securities Reconciliation [Table Text Block] Amortization of Net Losses/(Gains) Defined Benefit Plan, Amortization of Gain (Loss) Amortized cost and fair values of debt securities by contractual maturity Investments Classified by Contractual Maturity Date [Table Text Block] Loss Reserve [Roll Forward] Loss Reserve [Roll Forward] A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. Federal Home Loan Bank Advances (FHLB) Federal Home Loan Bank Advances [Member] Unearned premium reserves Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Unearned Premiums Reserve Other Adjustments Defined Benefit Plan, Other Cost (Credit) Cash dividends Cash dividends Dividends, Cash Retained earnings Retained Earnings [Member] Total financial liabilities Debt Instrument, Fair Value Disclosure Proceeds from contribution from parent Proceeds from Contributions from Parent Losses and expenses: Expenses: Benefits, Losses and Expenses [Abstract] Other items removed from inventory Other items removed from inventory Primary Default Inventory, Other Items Removed Other deductions from the primary default inventory, including items removed for settlements New Notices Primary Default Inventory, New Notices Additions to the primary default inventory resulting from new notices of defaulted loans. Total fixed income securities Fixed income securities Debt Securities [Member] Percent of international mutual funds equity allocation in emerging markets (in hundredths) Percent of international mutual funds equity allocation in emerging markets The investment in international mutual funds (emerging markets), as a percentage of the equity investments range. Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Debt Instrument, Redemption, Period Four Debt Instrument, Redemption, Period Four [Member] Development of funded status Development of Funded Status [Table Text Block] Tabular disclosure of pension plans and/or other employee benefit plans': 1) actuarial value of benefit obligations; 2) funded status; and 3) accumulated other comprehensive income (loss) recognized as components of net periodic benefit cost, including the net gain (loss), net prior service cost or credit, and net transition asset or obligation. Amortization of Net Transition Obligation/(Asset) Defined Benefit Plan, Amortization of Transition Asset (Obligation) FHLBC fixed interest rate Federal Home Loan Bank, Advances, Interest Rate Entity Well-known Seasoned Issuer Entity Well-known Seasoned Issuer Dividend to parent, distribution of investment in subsidiary Dividend, Distribution of Investment in Subsidiary Amount of distribution, in form of a dividend, to holding company of investment in subsidiary. Other Other Tax Expense (Benefit) Statutory Capital [Abstract] Statutory Capital [Abstract] Prior years Prior years Prior Year Claims and Claims Adjustment Expense Basic (in dollars per share) Basic earnings per share (in dollars per share) Earnings Per Share, Basic Operating lease, expense Operating Lease, Expense Restricted stock outstanding at beginning of period (in shares) Restricted stock outstanding at end of period (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number Pool insurance notice inventory (in number of loans) Pool insurance notice inventory The number of loans included in the pool insurance notice inventory as of the end of the reporting period. Due after one year through five years Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, after Year One Through Five Interest expense Interest expense Interest Expense, Debt 2020 Plan 2020 Plan [Member] 2020 Plan Fair Value Measurement [Domain] Fair Value Measurement [Domain] Diluted earnings per share [Abstract] Earnings Per Share, Diluted [Abstract] Closing sale price of our common stock for consideration of redemption (in dollars per share) Debt Instrument Convertible Conversion Price 2 The price per share of the conversion feature embedded in the debt instrument. US Treasury (UST) Interest Rate US Treasury (UST) Interest Rate [Member] Cumulative Effect, Period of Adoption, Adjustment Cumulative Effect, Period of Adoption, Adjustment [Member] Other Other Noncash Income (Expense) Net deferred tax liability Deferred Tax Liabilities, Net Increase in contingency reserve Statutory Accounting Practices, Prescribed Practice, Amount Restricted cash and cash equivalents Restricted Cash and Cash Equivalents Percentage of Amount Assumed to Net SEC Schedule, 12-17, Insurance Companies, Reinsurance, Premium, Percentage Assumed to Net Debt Instrument, Redemption, Period Two Debt Instrument, Redemption, Period Two [Member] Entity Voluntary Filers Entity Voluntary Filers Defined Benefit Plan, Plan Assets, Category [Domain] Defined Benefit Plan, Plan Assets, Category [Domain] Plan Name [Axis] Plan Name [Axis] Statutory net income Statutory Accounting Practices, Statutory Net Income Amount Fixed Income/Cash Fixed Income Funds [Member] Long-term debt, carrying value Long-term Debt Quoted Prices in Active Markets for Identical Assets (Level 1) Fair Value, Inputs, Level 1 [Member] Other liabilities Other Liabilities Quota Share Reinsurance Agreement, 2023 Quota Share Reinsurance Agreement, 2023 [Member] Quota Share Reinsurance Agreement, 2023 Direct Direct Premiums Written Income Tax Disclosure [Abstract] Income Tax Disclosure [Abstract] Entity Small Business Entity Small Business Lessee, Operating Lease, Liability, Payment, Due [Abstract] Lessee, Operating Lease, Liability, Payment, Due [Abstract] Cash equivalents Cash and Cash Equivalents [Member] Scenario [Axis] Scenario [Axis] Plan Amendments Defined Benefit Plan, Benefit Obligation, Increase (Decrease) for Plan Amendment Excess of Loss Reinsurance Agreements, Home Re Entities Excess of Loss Reinsurance Agreements, Home Re Entities [Member] Excess of Loss Reinsurance Agreements, Home Re Entities [Member] Additional Paid in Capital Additional Paid in Capital Schedule of fair value of plan assets Schedule of Defined Benefit Plans Disclosures [Table Text Block] FHLBC advances Federal Home Loan Bank Advances Liabilities and shareholders' equity Liabilities and Equity [Abstract] Schedule of Investment Income, Reported Amounts, by Category [Table] Investment Income [Table] Contingency reserve Statutory Accounting Practices, Contingency Reserve Contingency reserve liability recorded under Statutory Accounting Practices to protect against loss during periods of extreme contraction. 4 - 11 months (in hundredths) Primary Default Inventory, four to eleven months, Percentage The percentage of loans that have been in the primary default inventory for at least four months but no greater than eleven months as of the balance sheet date. 4 - 11 months Primary Default Inventory, four to eleven months The number of loans that have been in the primary default inventory for at least four months but no greater than eleven months as of the balance sheet date. Mortgage-backed Collateralized Mortgage Backed Securities [Member] Entity Interactive Data Current Entity Interactive Data Current Gross realized gains on sale of fixed income securities Debt Securities, Available-for-sale, Realized Gain Basis of Presentation Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Investment in subsidiaries, at equity in net assets Investment in subsidiaries, at equity in net assets The amount of the entity's total investments in subsidiaries (the equity in net assets of consolidated subsidiaries). Unearned premiums Unearned Premiums Other, net Deferred Tax Assets (Liabilities), Net, Other Deferred Tax Assets (Liabilities), Net, Other Insurance Subsidiaries Subsidiaries [Member] Unrecognized tax benefits Unrecognized Tax Benefits Total deferred tax assets Deferred Tax Assets, Gross Equity Securities, FV-NI, Gain (Loss) [Abstract] Equity Securities, FV-NI, Gain (Loss) [Abstract] Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Gross Unrealized Gains Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax Entity Address, State or Province Entity Address, State or Province Quota Share Reinsurance Agreements, 2017 & 2018 Quota Share Reinsurance Agreements, 2017 & 2018 [Member] Quota Share Reinsurance Agreements, 2017 & 2018 Amortization of deferred policy acquisition costs Deferred Policy Acquisition Costs, Amortization Expense Less: Amounts reclassified from AOCL Reclassification from AOCI, Current Period, Net of Tax, Attributable to Parent Increase (decrease)in estimated claim severity on primary delinquencies Increase Decrease in Estimated Severity Primary Defaults [Member] The increase (decrease) in estimated severity on primary defaults that occurred in prior periods. Real Estate Acquired Real Estate Acquired [Member] This category includes information about real estate acquired by the entity through claim settlement. Purchase of senior notes Early repayment of debt Early Repayment of Senior Debt Total Amortization Defined Benefit Plan, Total Amortization Total amortization included in the amount of net periodic benefit cost that may include the following components: 1) gains or losses recognized in net periodic benefit cost; 2) transition obligation or asset recognized in net periodic benefit cost; and 3) prior service cost or credit recognized in net periodic benefit cost relating to benefit changes attributable to plan participants' prior service pursuant to a plan amendment or a plan initiation. Premiums receivable Increase (Decrease) in Premiums Receivable Equity securities Equity Securities [Member] Accounting Policies [Abstract] Accounting Policies [Abstract] Expected Benefit Payments for the Year Ending: Current plus 4 Defined Benefit Plan, Expected Future Benefit Payment, Year Four Foreign government debt Foreign Bonds Debt Security, Government, Non-US [Member] Senior Notes Senior Notes, Fair Value Disclosure Senior Notes, Fair Value Disclosure Document Transition Report Document Transition Report Percent of inventory in default for more than 36 consecutive months Primary Default Inventory Twelve Months Or More, Percent Of Primary Default Inventory In Default For Twelve Months Or More In Default For More Than Thirty Six Consecutive Months Primary Default Inventory Twelve Months Or More, Percent Of Primary Default Inventory In Default For Twelve Months Or More In Default For More Than Thirty Six Consecutive Months Common stock (one dollar par value, shares authorized 1,000,000; shares issued 2021 - 371,353; 2020 - 371,353; shares outstanding 2021 - 320,336; 2020 - 338,573) Common Stock, Value, Issued Weighted-average period for recognition of compensation cost Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition Restricted stock outstanding at end of period (in dollars per share) Restricted stock outstanding at end of period (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Net increase (decrease) in cash and cash equivalents and restricted cash and cash equivalents Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Excluding Exchange Rate Effect SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items] SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items] Profit commission receivable Increase Decrease in Profit Commission Receivable The net change during the reporting period in the amount of profit commission receivable. Leases Lessee, Operating Leases [Text Block] Minimum percentages of gain loss consider for amortization (in hundredths) Minimum percentages of gain loss consider for amortization Represents minimum percentages of gain loss consider for amortization. Schedule of carrying value and fair value of financial liabilities measured on a recurring basis Fair Value, by Balance Sheet Grouping [Table Text Block] CMBS Commercial Mortgage Backed Securities [Member] Debt securities without single maturity date Debt Securities, Available-for-sale, Maturity, without Single Maturity Date, Fair Value SCHEDULE I - SUMMARY OF INVESTMENTS - OTHER THAN INVESTMENTS IN RELATED PARTIES SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Text Block] Funded Status - Overfunded/(Underfunded) Defined Benefit Plan, Funded (Unfunded) Status of Plan Other invested assets, at cost Other Investments Reclassification out of Accumulated Other Comprehensive Income [Axis] Reclassification out of Accumulated Other Comprehensive Income [Axis] ICFR Auditor Attestation Flag ICFR Auditor Attestation Flag Occurring during year - Prior Service Cost Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), before Tax Investments Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] Legal Entity [Axis] Legal Entity [Axis] Dilutive securities - Share based compensation (in shares) Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements Fixed income Fixed Maturities [Member] Health Care Cost Trend Rate Assumed for Next Year (in hundredths) Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Next Fiscal Year Cost of settlements Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement and Curtailment 2015 QSR Quota Share Reinsurance Agreement, 2015 [Member] Quota Share Reinsurance Agreement, 2015 [Member] Ceding commission, percentage Reinsurance, Quota Share Reinsurance Agreement, Terms, Ceding Commission, Percent Reinsurance, Quota Share Reinsurance Agreement, Terms, Ceding Commission, Percent Net reserve at beginning of year Liability for Unpaid Claims and Claims Adjustment Expense, Net Dividends paid to the parent company SEC Schedule, 12-04, Cash Dividends Paid to Registrant, Subsidiaries and Equity Method Investees Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract] Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract] Reconciliation of beginning and ending balance for assets and liabilities measured at fair value with significant unobservable inputs (level 3) Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block] Common stock, dividends, per share, declared (in dollars per share) Common Stock, Dividends, Per Share, Declared Entity [Domain] Entity [Domain] Total debt securities with single maturity date Available For Sale Securities, Debt Maturities, With Single Maturity Date, Fair Value This item represents the total fair value of debt securities, categorized neither as held-to-maturity nor trading securities, which have a single maturity date. Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Convertible Junior Subordinated Debentures, at 9% per annum, Due 2063 Convertible Subordinated Debt [Member] Less than 12 months Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months Variable Rate [Axis] Variable Rate [Axis] Other comprehensive income (loss) before reclassifications OCI, before Reclassifications, Net of Tax, Attributable to Parent Adjusted statutory net income measurement period Statutory Accounting Practices, Statutory Amount Available For Dividend Payments Without Regulatory Approval, Measurement, Measurement Period Statutory Accounting Practices, Statutory Amount Available For Dividend Payments Without Regulatory Approval, Measurement, Measurement Period Net proceeds cap (in hundredths) Net proceeds cap The percentage calculated as the average closing price of the entity's common stock times the number of the entity's 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 the entity's most recent publicly released financial statements. Amount at which shown in the balance sheet SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties, Amount Other Adjustment Defined Benefit Plan, Benefit Obligation, Increase (Decrease) for Other Change Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items] Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items] Debt Securities, Available-for-sale [Line Items] Debt Securities, Available-for-sale [Line Items] Due after one year through five years Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, after Year One Through Five Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Document Fiscal Year Focus Document Fiscal Year Focus Variable Rate [Domain] Variable Rate [Domain] Paid-in capital Additional Paid-in Capital [Member] Expected Benefit Payments for the Year Ending: Current plus 6 - 10 Defined Benefit Plan, Expected Future Benefit Payment, after Year Five for Next Five Years Common stock, dividends, per share, cash paid (in dollars per share) Common Stock, Dividends, Per Share, Cash Paid $1,000 Increase/Decrease In Average Severity Reserve Factor $1,000 Increase/Decrease In Average Severity Reserve Factor [Member] $1,000 Increase/Decrease In Average Severity Reserve Factor Pooled Equity Accounts Pooled Equity Accounts [Member] Funds from many individual investors that are aggregated for the purposes of investment, as in the case of a mutual or pension fund. Investors in pooled fund investments benefit from economies of scale, which allow for lower trading costs per dollar of investment, diversification and professional money management. Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Accrued interest Interest Payable Aging of the Primary Default Inventory [Abstract] Aging of the Primary Default Inventory [Abstract] Loss Reserves Liability for Future Policy Benefits and Unpaid Claims Disclosure [Text Block] Benefit Payments Directly by Company Benefit Payments paid directly by Company Defined Benefit Plan, Benefits Paid Directly by Company The amount of payments made directly by the entity for which participants are entitled under a pension plan, including pension benefits, death benefits, and benefits due on termination of employment. Also includes payments made under a postretirement benefit plan, including prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services. This item represents a periodic decrease to the plan obligations and a decrease to plan assets. Loss reserves Change in loss reserves (+/-) Increase (Decrease) in Liability for Claims and Claims Adjustment Expense Reserve Pension and Supplemental Executive Retirement Plans Other Pension, Postretirement and Supplemental Plans [Member] Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Table] Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Table] Maximum Maximum [Member] Share-based Payment Arrangement [Abstract] Share-based Payment Arrangement [Abstract] Reconciliation of effective income tax rate [Abstract] Effective Income Tax Rate Reconciliation, Percent [Abstract] Components of provisions for (benefit from) income taxes [Abstract] Components of Income Tax Expense (Benefit), Continuing Operations [Abstract] Gross losses Equity Securities, FV-NI, Unrealized Loss Cede rate, option 1 Reinsurance, Quota Share Reinsurance Agreement, Terms, Ceding Rate, Percent, Option One Reinsurance, Quota Share Reinsurance Agreement, Terms, Ceding Rate, Percent, Option One Award Type [Axis] Award Type [Axis] Lessee, operating lease, liability, maturity Lessee, Operating Lease, Liability, Maturity [Table Text Block] Total shareholders' equity Balance, beginning of year Balance, end of year Stockholders' Equity Attributable to Parent Reacquisition of convertible junior subordinated debentures-equity component Reacquisition of convertible junior subordinated debentures-equity component Adjustments to Additional Paid in Capital, Equity Component of Convertible Debt, Subsequent Adjustments City Area Code City Area Code Premiums earned, ceded Ceded premiums earned Ceded to Other Companies Ceded Premiums Earned (Decrease) in estimated claim rate on primary delinquencies Increase Decrease in Expected Claim Rate [Member] The increase (decrease) in the expected claim rate on primary and/or pool defaults that occurred in prior periods. Repurchase of common stock Payments for Repurchase of Common Stock Estimated useful life Property, Plant and Equipment, Useful Life Shareholders' equity: Shareholders’ equity: Stockholders' Equity Attributable to Parent [Abstract] Current Federal Current Income Tax Expense (Benefit) Debt instrument, face amount Debt Instrument, Face Amount Total Expense for Year Defined Benefit Plan, Net Periodic Benefit Cost (Credit) SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Table] SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Table] Policyholder Benefits and Claims Incurred, Net [Abstract] Policyholder Benefits and Claims Incurred, Net [Abstract] Income tax benefit from compensation cost Share-based Payment Arrangement, Expense, Tax Benefit Gain (Loss) on Investments, Including Marketable Securities and Investments Held at Cost, Categories of Investments [Domain] Other than Temporary Impairment, Credit Losses Recognized in Earnings, Categories of Investments [Domain] Schedule of Defined Benefit Plans Disclosures [Table] Schedule of Defined Benefit Plans Disclosures [Table] Remaining term of operating leases (in years) Lessee, Operating Lease, Term of Contract RSUs subject only to service conditions Restricted Stock Units (RSUs) [Member] Schedule of Condensed Financial Statements [Table] Condensed Financial Statements [Table] Total deferred tax liabilities Deferred Tax Liabilities, Gross Matching contribution rate on employees' contributions (in hundredths) Defined Contribution Plan, Employer Matching Contribution, Percent of Match Equity securities Defined Benefit Plan, Equity Securities [Member] 2019 QSR Quota Share Reinsurance Agreement, 2019 [Member] Quota Share Reinsurance Agreement, 2019 [Member] Restricted Stock/Restricted Stock Units Restricted Stock and Restricted Stock Units [Member] Shares and stock units that an entity has not yet issued because the agreed-upon consideration, such as employee services, has not yet been received. CONDENSED STATEMENTS OF OPERATIONS Income Statement [Abstract] Actual Benefit Payments for the Year Ending: Current Benefit Plan Payments, Total Plan Payments The amount of payments made from the benefit fund and company funds for which participants are entitled under a pension plan, including pension benefits, death benefits, and benefits due on termination of employment. May also include payments made under a postretirement benefit plan. This item represents a periodic decrease to the plan obligations and a decrease to plan assets. Entity Registrant Name Entity Registrant Name Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, by Asset Class [Domain] Asset Class [Domain] Net deferred tax assets and liabilities [Abstract] Components of Deferred Tax Assets and Liabilities [Abstract] Effect of reinsurance agreements on premiums earned and losses incurred Effects of Reinsurance [Table Text Block] FHLB Advance Notes Payable, Fair Value Disclosure Plan Participants' Contributions Defined Benefit Plan, Benefit Obligation, Contributions by Plan Participant Real Estate Real Estate [Member] Provision for income taxes Income tax benefit (expense) Income Tax Expense (Benefit) Expected Benefit Payments for the Year Ending: Current plus 3 Defined Benefit Plan, Expected Future Benefit Payment, Year Three Insurance [Abstract] Insurance [Abstract] Maximum age for qualified employees for both medical and dental benefits Postretirement Benefits Liability, Maximum Age For Qualified Employees Postretirement Benefits Liability, Maximum Age For Qualified Employees Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Table] Entity Tax Identification Number Entity Tax Identification Number Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward] Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward] Investment Type [Axis] Investment Type [Axis] Document Fiscal Period Focus Document Fiscal Period Focus Dividends received from subsidiaries SEC Schedule, 12-04, Cash Dividends Paid to Registrant, Consolidated Subsidiaries Total Lessee, Operating Lease, Liability, to be Paid Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items] Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] Forfeited (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period Industrial, miscellaneous and all other Industrial, Miscellaneous, and All Others [Member] Schedule of Stock by Class [Table] Schedule of Stock by Class [Table] Cash Equivalents Other Assets, Fair Value Disclosure Share-Based Compensation Share-based Payment Arrangement [Policy Text Block] Maturities, Fair Value [Abstract] Debt Securities, Available-for-sale, Fair Value, Fiscal Year Maturity [Abstract] CONDENSED BALANCE SHEETS Statement of Financial Position [Abstract] Maximum number of trading days Maximum number of trading days The maximum number of trading days within a specified time period that the closing sale price of the entity's common stock exceeds the prevailing conversion price of the debentures by a specified percentage. Cash flows from financing activities: Net Cash Provided by (Used in) Financing Activities, Continuing Operations [Abstract] Other underwriting and operating expenses, net Other Underwriting Expense Quota Share Reinsurance Agreements Quota Share Reinsurance Agreements [Member] Quota Share Reinsurance Agreements Equity Component [Domain] Equity Component [Domain] Benefit plans Deferred Tax Liabilities, Tax Deferred Expense, Compensation and Benefits, Employee Benefits Deferred Tax Liabilities, Tax Deferred Expense, Compensation and Benefits, Employee Benefits Maximum exposure to loss Maximum Exposure Associated With Other Discussions Legal Proceedings Estimated maximum exposure associated with other discussions and legal proceedings related to claims paying practices. 2022 Lessee, Operating Lease, Liability, to be Paid, Year One Period preceding election to convert Period preceding election to convert The period immediately prior to an election to convert debentures during which the average price of shares traded is determined for the purpose of calculating the conversion rate. Defined Benefit Plan, Plan Assets, Category [Axis] Defined Benefit Plan, Plan Assets, Category [Axis] Debt issuance costs Debt Issuance Costs, Gross Maximum number of shares of common stock issuable under the Alternative Payment Mechanism (in shares) Maximum number of shares of common stock issuable under the Alternative Payment Mechanism The maximum number of shares of common stock, including shares underlying qualifying warrants, that the entity may be required to issue pursuant to the Alternative Payment Mechanism under the note agreement(s). 12 months or more (in hundredths) Primary Default Inventory, Twelve Months or More, Percentage The percentage of loans that have been in the primary default inventory for twelve months or more as of the balance sheet date. Other revenue Other Income Reinsurance recoverable on paid losses Reinsurance Recoverable for Paid Claims and Claims Adjustments Purchases of investments Payments to Acquire Investments Liabilities: Liabilities [Abstract] Year-end asset allocations of the plans Schedule of Allocation of Plan Assets [Table Text Block] Proceeds from sales of investments Proceeds from Sale, Maturity and Collection of Investments Change in projected benefit obligation Schedule of Changes in Projected Benefit Obligations [Table Text Block] 2025 Lessee, Operating Lease, Liability, to be Paid, Year Four Change in estimates related to pool reserves, LAE reserves, reinsurance and other Increase Decrease Related To Pool Reserves, LAE Reserves and Reinsurance [Member] The decrease in losses incurred related to prior years related to pool reserves, LAE reserves, reinsurance and other. Income before tax Total reclassifications Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Significant Other Observable Inputs (Level 2) Fair Value, Inputs, Level 2 [Member] Total losses and expenses Benefits, Losses and Expenses Income tax benefit (expense) Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, Tax, Attributable to Parent Auditor Location Auditor Location Total primary default inventory (in hundredths) Primary default inventory, Percentage The percentage of loans in the primary default inventory. Quota share reinsurance agreements on premiums earned and losses incurred Effect Of Quota Share Reinsurance Agreements On Premiums Earned And Losses Incurred [Table Text Block] Tabular disclosure of the effect of quota share reinsurance agreements on premiums earned and losses incurred. Total Debt Securities, Available-for-sale, Unrealized Loss Position Fixed income, amortized cost Total at end of period Debt Securities, Available-for-sale, Amortized Cost Deferred compensation Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits Significant Accounting Policies [Table] Significant Accounting Policies [Table] Significant Accounting Policies Contingent termination fee Reinsurance, Quota Share Reinsurance Agreement, Terms, Contingent Termination Fee Reinsurance, Quota Share Reinsurance Agreement, Terms, Contingent Termination Fee Calculation of earnings (loss) per share Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Profit commission Reinsurance, Profit Commission Reinsurance, Profit Commission Other comprehensive income (loss), net of tax Other comprehensive (loss) income Other comprehensive income (loss), net of tax Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent Premiums Earned, Net [Abstract] Premiums Earned, Net [Abstract] Title of 12(b) Security Title of 12(b) Security Return premium accrual Increase (Decrease) in Other Insurance Liabilities Debt securities without single maturity date Debt Securities, Available-for-sale, Maturity, without Single Maturity Date, Amortized Cost Common stock, shares authorized (in shares) Common Stock, Shares Authorized Dividend to parent, distribution of interest in 9% Debentures Dividend, Distribution of Interest of Convertible Junior Subordinated Debentures Amount of distribution, in form of a dividend, to holding company of interest in convertible junior subordinated debentures. Income tax benefit (expense) Other Comprehensive Income (Loss), Available-for-sale Securities, Tax, Portion Attributable to Parent Diluted income available to common shareholders Net Income (Loss) Available to Common Stockholders, Diluted Document Type Document Type Reconciliation of beginning and ending loss reserves Schedule of Liability for Unpaid Claims and Claims Adjustment Expense [Table Text Block] Stated interest rate (in hundredths) Debt Instrument, Interest Rate, Stated Percentage Investment income Gross Investment Income, Operating Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Equity securities, cost Equity Securities, FV-NI, Cost Maximum investment in international mutual funds (in hundredths) Defined Benefit Plan, Maximum investment in international mutual funds The maximum investment in international mutual funds, as a percentage of the equity investments range, to total plan assets as of the measurement date of the latest statement of financial position. Losses incurred, assumed Policyholder Benefits and Claims Incurred, Assumed Maturities, Amortized Cost [Abstract] Debt Securities, Available-for-sale, Amortized Cost, Fiscal Year Maturity [Abstract] Cash Balance Interest Crediting Rate Used to Determine Benefit Obligation (in hundredths) Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Weighted-Average Interest Crediting Rate 2017 QSR (2) Quota Share Reinsurance Agreement, 2017 [Member] Quota Share Reinsurance Agreement, 2017 [Member] Minimum number of payments past due to be in default Minimum Number Of Payments Past Due To Be In Default The number of payments past due in order for such loans to be considered in default. Gross realized gains on equity securities Equity Securities, FV-NI, Realized Gain Recognized during year - Prior Service (Cost)/Credit Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, before Tax Investments Investment, Policy [Policy Text Block] Net cash provided by (used in) financing activities Net Cash Provided by (Used in) Financing Activities Treasury stock at cost (shares 2021 - 51,017; 2020 - 32,779) Treasury Stock, Value Related Party Transaction [Line Items] Related Party Transaction [Line Items] Minimum number of consecutive interest periods for which interest payments may be deferred Minimum number of consecutive interest periods for which interest payments may be deferred The minimum number of consecutive interest periods for which interest payments may be deferred pursuant to an optional deferral provision under the note agreement(s). Award vesting period Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Ceded Ceded Premiums Written Decrease (increase) in unearned premiums (Increase) Decrease in Unearned Premiums, Net Cures Primary Default Inventory, Cures Deductions from the primary default inventory resulting from loans in default being brought current. Summary of restricted stock or restricted stock unit activity Share-based Payment Arrangement, Restricted Stock and Restricted Stock Unit, Activity [Table Text Block] For securities in an unrealized loss position, percentage of fair value to amortized cost (in hundredths) Percentage Of Fair Value To Amortized Cost Securities in Unrealized Loss Position The percentage of total fair value amount to total amortized cost amount of the company's securities in an unrealized loss position. Fair Value Measurements Fair Value Disclosures [Text Block] Loss Reserves Liability Reserve Estimate, Policy [Policy Text Block] Parenthetical information [Abstract] Parenthetical information [Abstract] Available-for-Sale Securities Available-for-sale Securities [Member] Reinsurance recoverable on paid losses Increase Decrease In Reinsurance Recoverable On Paid Losses The net change during the reporting period in the amount of receivables currently due from reinsurers for ceded claims paid. Revenues: Revenues [Abstract] Document Period End Date Document Period End Date Losses incurred, direct Policyholder Benefits and Claims Incurred, Direct Consolidated Entities [Domain] Consolidated Entities [Domain] Cash flows from investing activities: Net Cash Provided by (Used in) Investing Activities, Continuing Operations [Abstract] Accrued investment income Accrued Investment Income Receivable Investment income, net of expenses Net investment income Net Investment Income Condensed Financial Statements, Captions [Line Items] Condensed Financial Statements, Captions [Line Items] Home office and equipment, net Property, Plant and Equipment, Net Operating expenses Operating Expenses Rescissions and denials Primary Default Inventory, Rescissions and Denials Deductions from the primary default inventory resulting from rescissions and denials. Repayments of long-term debt Repayments of Long-term Debt Earnings per share: Earnings Per Share [Abstract] Earnings Per Share [Abstract] Reissuance of treasury stock, net under share-based compensation plans Stock Issued During Period, Value, Treasury Stock Reissued For Share Based Compensation Stock Issued During Period, Value, Treasury Stock Reissued For Share Based Compensation Recognized net gains (losses) on equity securities still held Equity Securities, FV-NI, Unrealized Gain (Loss) Total revenues Revenues Probable loss contingency accrual Loss Contingency Accrual Direct domestic primary risk in force Direct Domestic Primary Risk In Force The insurance in force multiplied by the insurance coverage percentage. Number of securities in unrealized loss position Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions Schedule of Related Party Transactions, by Related Party [Table] Schedule of Related Party Transactions, by Related Party [Table] Percent of total trust assets invested in cash or direct U.S. federal government obligations Reinsurance Retention Policy, Percent Of Total Trust Assets Invested In Cash Or Direct U.S. Federal Government Obligations Reinsurance Retention Policy, Percent Of Total Trust Assets Invested In Cash Or Direct U.S. Federal Government Obligations Entity Current Reporting Status Entity Current Reporting Status Net premiums written Premiums Written, Net Plan Assets at Fair Value Fair Value of Plan Assets at Beginning of Year Fair Value of Plan Assets at End of Year Defined Benefit Plan, Plan Assets, Amount Effective income tax provision rate (in hundredths) Effective Income Tax Rate Reconciliation, Percent Commercial paper Other Other Debt Obligations [Member] Current plus 1 Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year Other Adjustments Defined Benefit Plan, Plan Assets, Period Increase (Decrease) Debt Instrument, Redemption, Period One Debt Instrument, Redemption, Period One [Member] Leases [Abstract] Leases [Abstract] Net changes in benefit plan assets and obligations Other Comprehensive (Income) Loss, Defined Benefit Plan, before Tax, after Reclassification Adjustment, Attributable to Parent Income Taxes Income Tax, Policy [Policy Text Block] Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income (Loss) [Line Items] Reserve at beginning of year Reserve at end of year Liability for Claims and Claims Adjustment Expense Entity Address, Postal Zip Code Entity Address, Postal Zip Code Home Re 2019-1 Home Re 2019-1 [Member] Home Re 2019-1 [Member] Weighted average common shares outstanding - diluted (in shares) Weighted-average shares - diluted (in shares) Weighted Average Number of Shares Outstanding, Diluted Income Taxes Income Tax Disclosure [Text Block] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Basis spread on variable rate Debt Instrument, Basis Spread on Variable Rate Components of net periodic benefit cost Schedule of Net Benefit Costs [Table Text Block] Total losses incurred Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims Investment expenses Investment Income, Investment Expense CONDENSED STATEMENTS OF CASH FLOWS Statement of Cash Flows [Abstract] Class of Stock [Line Items] Class of Stock [Line Items] Entity Address, Address Line One Entity Address, Address Line One Interest paid Interest Paid, Including Capitalized Interest, Operating and Investing Activities Accumulated depreciation of home office and equipment Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Change in unrealized investment gains and losses Net of taxes Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax, Portion Attributable to Parent Premium Deficiency Reserve Premium Deficiency Reserves [Policy Text Block] Disclosure of accounting policy for premium deficiency reserves established when the present value of future losses and expenses exceeds the present value of expected future premium and already established reserves. Entity Shell Company Entity Shell Company Deferred insurance policy acquisition costs Deferred Policy Acquisition Cost Payment of withholding taxes related to share-based compensation net share settlement Payment, Tax Withholding, Share-based Payment Arrangement Domestic Mutual Funds Domestic Mutual Funds [Member] Investment in a company that brings together money from many people and invests it in domestic stocks, bonds or other assets. The combined holdings of stocks, bonds or other assets the fund owns are known as its portfolio. Each investor in the fund owns shares, which represent a part of these holdings. Assumed Assumed Premiums Written Losses incurred, ceded Ceded losses incurred Policyholder Benefits and Claims Incurred, Ceded Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] Reclassification from Accumulated Other Comprehensive Income Reclassification out of Accumulated Other Comprehensive Income [Member] Employee contributions subject to employer match (in hundredths) Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay Current Fiscal Year End Date Current Fiscal Year End Date Summary of restricted stock or restricted stock unit activity [Abstract] Summary of restricted stock or restricted stock unit activity [Abstract] Statement [Table] Statement [Table] Total losses paid Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid Net investment income Investment Income [Table Text Block] Expected Benefit Payments for the Year Ending: Current plus 5 Defined Benefit Plan, Expected Future Benefit Payment, Year Five Unrecognized compensation cost Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount Home Re 2020-1 Home Re 2020-1 [Member] Home Re 2020-1 Debt Instrument, Redemption, Period [Domain] Debt Instrument, Redemption, Period [Domain] Statistical Measurement [Axis] Statistical Measurement [Axis] Subsequent Event Subsequent Event [Member] Net decrease in payables for securities Increase (Decrease) in Broker-Dealer Related Receivables (Payables), Net Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] Discretionary profit sharing contribution as a percentage of participant's eligible compensation (in hundredths) Discretionary Profit Sharing Contribution As Percentage Of Participants Eligible Compensation The company's discretionary profit sharing contribution as a percentage of each participant's eligible compensation. Less than 12 months Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss Premiums written: Premiums Written, Gross [Abstract] Scenario [Domain] Scenario [Domain] Adjustments to reconcile net income to net cash provided by operating activities: Adjustments to reconcile net income to net cash provided by operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Reinsurance Reinsurance Accounting Policy [Policy Text Block] Debt Instrument, Redemption, Period [Axis] Debt Instrument, Redemption, Period [Axis] Net benefit plan assets and obligations recognized in shareholders' equity Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] Schedule of Investment Income, Reported Amounts, by Category [Line Items] Net Investment Income [Line Items] 12 months or greater Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss Deferred Federal Deferred Income Tax Expense (Benefit) Senior notes Senior notes Senior Notes Cash and Cash Equivalents Cash and Cash Equivalents, Unrestricted Cash and Cash Equivalents, Policy [Policy Text Block] Federal statutory income tax rate (in hundredths) Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Earnings per Share Earnings Per Share, Policy [Policy Text Block] Fair Value, Measurements, Fair Value Hierarchy [Domain] Fair Value Hierarchy and NAV [Domain] Net income Net income Net income Net Income (Loss) Attributable to Parent Benefit Plans Pension and Other Postretirement Plans, Policy [Policy Text Block] Interest Cost Defined Benefit Plan, Interest Cost SCHEDULE II - CONDENSED FINANCIAL INFORMATION OF REGISTRANT Condensed Financial Information of Parent Company Only Disclosure [Text Block] Statistical Measurement [Domain] Statistical Measurement [Domain] Liability for Claims and Claims Adjustment Expense [Line Items] Liability for Claims and Claims Adjustment Expense [Line Items] Schedule of investment allocation strategies Schedule of Investment Allocation Strategies [Table Text Block] Schedule of Investment Allocation Strategies [Table Text Block] Tax exempt municipal bond interest (in hundredths) Effective Income Tax Rate Reconciliation, Tax Exempt Income, Percent Ceding commisisons Reinsurance Ceding Commission Earned Reinsurance Ceding Commission Earned Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Paid-in capital Additional Paid in Capital, Common Stock Percentage of statutory policyholders surplus used to determine maximum allowable dividends Percentage of statutory policyholders surplus used to determine maximum allowable dividends The percentage of statutory policyholders' surplus, as defined, as of the preceding calendar year end which is used in the determination of the maximum allowable dividends that the insurance subsidiaries may pay in any twelve-month period without regulatory approval by the Office of the Commissioner of Insurance of the State of Wisconsin. Public utilities Public Utility, Bonds [Member] Rate to Which the Cost Trend Rate is Assumed to Decline (Ultimate Trend Rate) (in hundredths) Defined Benefit Plan, Ultimate Health Care Cost Trend Rate Expected Return on Assets Defined Benefit Plan, Expected Return (Loss) on Plan Assets Deferred Insurance Policy Acquisition Costs Deferred Policy Acquisition Costs, Policy [Policy Text Block] Retirement Benefits [Abstract] Retirement Benefits [Abstract] Proceeds from maturity of fixed income securities Proceeds From Sale, Maturity And Collection of Securities Proceeds From Sale, Maturity And Collection of Securities Entity File Number Entity File Number Redemption price, percentage (in hundredths) Debt Instrument, Redemption Price, Percentage Equity compensation APIC, Share-based Payment Arrangement, Increase for Cost Recognition One Percentage Point Increase/Decrease In Average Claim Rate Reserve Factor One Percentage Point Increase/Decrease In Average Claim Rate Reserve Factor [Member] One Percentage Point Increase/Decrease In Average Claim Rate Reserve Factor Percent of international mutual funds equity allocation in companies primarily based in Europe and the Pacific Basin (in hundredths) Percent of international mutual funds equity allocation in companies primarily based in Europe and Pacific Basin The investment in international mutual funds primarily based in Europe and the Pacific Basin, as a percentage of the equity investments range. Rollforward of delinquent inventory roll-forward Rollforward of Primary Default Inventory [Table Text Block] Tabular disclosure of the activity related to loans in the primary default inventory. Amounts Reclassified From Accumulated Other Comprehensive Income [Abstract] Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract] Organization, Consolidation and Presentation of Financial Statements [Abstract] Organization, Consolidation and Presentation of Financial Statements [Abstract] Premium refund liability, expected claim payments Premium refund liability, expected claim payments The carrying amount for the estimate of premiums to be refunded on expected claim payments. Other invested assets Other Invested Assets, Fair Value Disclosure Fair value portion of other invested assets. Payment of original issue discount - senior notes Payment Of Original Issue Discount Senior Notes Payment Of Original Issue Discount Senior Notes 2021 QSR Quota Share Reinsurance Agreement, 2021 [Member] Quota Share Reinsurance Agreement, 2021 [Member] Risk to capital ratio of combined insurance operations at end of period Risk to capital ratio of combined insurance operations at end of period The risk-to-capital ratio of the entity's combined insurance operations as of the end of the reporting period. 5.75% Senior Notes due 2023 Five Point Seven Five Percent Senior Notes [Member] Five Point Seven Five Percent Senior Notes [Member] Primary claims received inventory included in ending default inventory Primary Default Inventory, Claims Received Inventory The number of loans in the primary default inventory that are in the claims received inventory. Total fair value of restricted stock vested Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value Granted (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value Actual Return on Assets Defined Benefit Plan, Plan Assets, Increase (Decrease) for Actual Return (Loss) Assets Assets [Abstract] Probable Loss On Litigation Claims Paying Practices Probable Loss On Litigation Claims Paying Practices [Member] The increase (decrease) in losses incurred related to prior years due to claims paying practices. Total debt securities with single maturity date Available For Sale Securities, Debt Maturities, With Single Maturity Date, Amortized Cost This item represents the total debt securities, categorized neither as held-to-maturity nor trading securities, which have a single maturity date, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments, as defined), and fair value hedge accounting adjustments, if any. For securities in an unrealized loss position, percentage backed by the U.S. Government (in hundredths) Percentage Backed By US Government The percentage of the company's securities in an unrealized loss position backed by the U.S. Government. Obligations of U.S. states and political subdivisions Municipal Bonds US States and Political Subdivisions Debt Securities [Member] Granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period Home office and equipment Property, Plant and Equipment, Policy [Policy Text Block] SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items] SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items] Unrealized appreciation in investments Deferred Tax Liabilities, Other Comprehensive Income Discount Rate Used to Determine Benefit Obligation(in hundredths) Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate Debt Instrument [Axis] Debt Instrument [Axis] Loss reserves Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Loss Reserves Annual loss ratio Annual Loss Ratio to Exhaust Profit Commission Loss Ratio Reinsurance Disclosures [Abstract] Reinsurance Disclosures [Abstract] Accrued investment income Increase (Decrease) in Accrued Investment Income Receivable Average paid claim reduction due to curtailments (in hundredths) Average paid claims reduction due to curtailments Average paid claim reduction due to curtailments. Amortization of Net Prior Service Cost/(Credit) Defined Benefit Plan, Amortization of Prior Service Cost (Credit) Minimum number of trading days Minimum number of trading days The minimum number of trading days within a specified time period that the closing sale price of the entity's common stock exceeds the prevailing conversion price of the debentures by a specified percentage. Convertible junior subordinated debentures Convertible junior subordinated debentures Convertible Subordinated Debt Reinsurance Policy [Domain] Reinsurance Policy [Domain] Reinsurance Policy, Type [Axis] Reinsurance Policy, Type [Axis] Net deferred tax assets and liabilities Schedule of Deferred Tax Assets and Liabilities [Table Text Block] Gain (Loss) on Securities [Line Items] Gain (Loss) on Securities [Line Items] Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] Prior years Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid, Prior Years Target asset allocations (in hundredths) Defined Benefit Plan, Plan Assets, Target Allocation, Percentage Occurring during year - Net Actuarial Losses/(Gains) Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, before Tax Total other comprehensive income (loss) Other Comprehensive Income (Loss), before Tax Remaining First Layer Retention Reinsurance Retention Policy, Amount Retained U.S. Treasury securities and obligations of U.S. government corporations and agencies U.S. Government Securities US Treasury and Government [Member] 2024 Lessee, Operating Lease, Liability, to be Paid, Year Three 3 months or less Primary Default Inventory, Three months or less The number of loans that have been in the primary default inventory for three months or less as of the balance sheet date. CLOs Collateralized Debt Obligations [Member] Accounts receivable - affiliates Due from Related Parties Profit sharing and 401(k) savings plan expenses Defined Contribution Plan, Cost Shares [Roll Forward] Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Annual loss ratio cap Reinsurance, Quota Share Reinsurance Agreement, Terms, Annual Loss Ratio Cap Reinsurance, Quota Share Reinsurance Agreement, Terms, Annual Loss Ratio Cap Unearned premiums Increase (Decrease) in Unearned Premiums Reinsurance recoverable on loss reserves Less reinsurance recoverable Reinsurance Recoverable for Unpaid Claims and Claims Adjustments Unvested Restricted Stock Units Unvested restricted stock units [Member] Refers to the unvested restricted stock units. Noncatastrophic Event [Axis] Noncatastrophic Event [Axis] Total assets Assets, Fair Value Disclosure Total liabilities and shareholders' equity Liabilities and Equity Other, net (in hundredths) Effective Income Tax Rate Reconciliation, Other Adjustments, Percent Deferred Policy Acquisition Cost Deferred Tax Liabilities, Deferred Expense Quota Share % Reinsurance, Quota Share Reinsurance Agreement, Terms, Quota Share, Percent Reinsurance, Quota Share Reinsurance Agreement, Terms, Quota Share, Percent 2025 and thereafter Lessee, Operating Lease, Liability, to be Paid, Year Five Change in unrealized gains (losses) OCI, Debt Securities, Available-for-Sale, Gain (Loss), after Adjustment, before Tax Benefit Payments from the Fund Defined Benefit Plan, Plan Assets, Benefits Paid 2018 QSR (2) Quota Share Reinsurance Agreement, 2018 [Member] Quota Share Reinsurance Agreement, 2018 [Member] Weighted average grant date fair market value [Abstract] Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Additional Disclosures [Abstract] Home Re 2021-2 Home Re 2021-2 [Member] Home Re 2021-2 Assets held in trust for the benefit of contractual counterparties Assets Held-in-trust Cash flows from operating activities: Net Cash Provided by (Used in) Operating Activities, Continuing Operations [Abstract] Earnings per Share Earnings Per Share [Text Block] Purchases of common stock Treasury Stock, Value, Acquired, Cost Method Shares repurchased, weighted average price per share (in dollars per share) Treasury Stock Acquired, Average Cost Per Share Summary of amounts disclosed under statutory accounting practices Statutory Accounting Practices Disclosure [Table Text Block] Expected Benefit Payments for the Year Ending: Current plus 2 Defined Benefit Plan, Expected Future Benefit Payment, Year Two Minimum Minimum [Member] Other, net Increase (Decrease) in Other Operating Assets and Liabilities, Net 2023 Lessee, Operating Lease, Liability, to be Paid, Year Two SEC Schedule, 12-17, Insurance Companies, Reinsurance [Abstract] SEC Schedule, 12-17, Insurance Companies, Reinsurance [Abstract] Income taxes - current and deferred Deferred Income Taxes and Other Tax Receivable, Current Other comprehensive income (loss), net of tax: Components of Other Comprehensive Income (Loss) [Abstract] Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract] Amount of policyholders position above or below required MPP Amount of policyholders position above or below required regulatory minimum The amount by which the entity's policyholders position (the insurer's net worth or surplus, contingency reserve and a portion of the reserves for unearned premiums) was above or below the required regulatory minimum of the entity's domiciliary state. Losses incurred, net Net losses incurred Policyholder Benefits and Claims Incurred, Net, Property, Casualty and Liability Risk to capital ratio Statutory Capital Requirements, Risk To Capital Ratio Statutory Capital Requirements, Risk To Capital Ratio Due after ten years Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, after Year 10 Cumulative Effect, Period of Adoption [Axis] Cumulative Effect, Period of Adoption [Axis] Insurance Disclosure Insurance Disclosure [Text Block] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table] 12 months or greater Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer Primary Default Inventory [Roll Forward] Primary Default Inventory [Roll Forward] A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. Revenue Recognition Revenue [Policy Text Block] Debt Debt Disclosure [Text Block] Components of the provision for (benefit from) income taxes Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] Share-based Compensation Plans Share-based Payment Arrangement [Text Block] Senior Notes Senior Notes [Member] Significant Unobservable Inputs (Level 3) Fair Value, Inputs, Level 3 [Member] Dividends paid Payments of Ordinary Dividends, Common Stock Premiums receivable Premiums Receivable, Net Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Table] Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Table] Share-based compensation arrangement, percent granted subject to performance conditions Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Subject to Performance Conditions Percent Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Subject to Performance Conditions Percent Settlements for commutations of coverage, pools of nonperforming loans Settlements For Commutations Of Coverage, Pools Of Nonperforming Loans [Member] Settlements For Commutations Of Coverage, Pools Of Nonperforming Loans [Member] Conversion rate (in shares per $1,000 note) Debt Instrument Convertible, Number of Equity Instruments If Debt Converted The number of shares that can be issued in exchange for the original debt if converted in a noncash (or part noncash) transaction. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or payments in the period. Reinsurance Reinsurance [Text Block] Basis of presentation Basis of Accounting, Policy [Policy Text Block] RSUs subject to performance conditions Performance Shares [Member] Other Postretirement Benefit Plan Other Postretirement Benefits Plan [Member] Contingencies Commitments and Contingencies Accumulated other comprehensive income, net of tax Accumulated other comprehensive income, net of tax Accumulated Other Comprehensive Income (Loss), Net of Tax Entity Emerging Growth Company Entity Emerging Growth Company Dilutive securities Dilutive Securities, Effect on Basic Earnings Per Share Payment of debt issuance costs Payments of Debt Issuance Costs Losses paid [Abstract] Losses paid [Abstract] Auditor Name Auditor Name Cover [Abstract] Cover [Abstract] Gross gains Equity Securities, FV-NI, Unrealized Gain Effects of Reinsurance [Table] Effects of Reinsurance [Table] Cumulative Effect, Period of Adoption, Adjusted Balance Cumulative Effect, Period of Adoption, Adjusted Balance [Member] Treasury stock, shares at cost (in shares) Treasury Stock, Shares Aging of the fair values of securities in an unrealized loss position Schedule of Unrealized Loss on Investments [Table Text Block] Rate of Compensation Increase Used to Determine Benefit Obligation (in hundredths) Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase Actual and estimated future contributions and actual and estimated future benefit payments Actual and Estimated Future Contributions and Actual and Estimated Future Benefit Payments [Table Text Block] Tabular disclosure of actual and estimated future contributions, and actual and estimated future benefit payments to be paid by pension plans and/or other employee benefit plans in each of the next five fiscal years and in the aggregate for the five fiscal years thereafter. Financial Instrument [Axis] Financial Instrument [Axis] Amortization period excess of loss reinsurance coverage Amortization Period Excess of Loss Reinsurance Coverage Amortization Period Excess of Loss Reinsurance Coverage Current income taxes Increase (Decrease) in Income Taxes Payable, Net of Income Taxes Receivable Schedule of Available-for-sale Securities [Table] Schedule of Available-for-sale Securities [Table] Net unrealized investment (losses) gains on securities without an allowance for credit losses Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, before Tax, Portion Attributable to Parent Carrying Value Reported Value Measurement [Member] Prior year development of the reserves Schedule of Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Table Text Block] Common stock Common Stock [Member] Cede rate, option 2 Reinsurance, Quota Share Reinsurance Agreement, Terms, Ceding Rate, Percent, Option Two Reinsurance, Quota Share Reinsurance Agreement, Terms, Ceding Rate, Percent, Option Two Gross Unrealized Losses Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax Components of the net deferred tax asset (liability) Net deferred tax asset liability [Table Text Block] Tabular disclosure of the components of net deferred tax asset (liability) recognized in an entity's statement of financial position. AOCI Attributable to Parent, Net of Tax [Roll Forward] AOCI Attributable to Parent, Net of Tax [Roll Forward] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Depreciation expense of home office and equipment Depreciation Assets held by insurance regulatory requirements Assets Held by Insurance Regulators Related party transaction amount Related Party Transaction, Amounts of Transaction Payment of original issue discount- convertible junior subordinated debentures Payment of Original Issue Discount, Convertible Junior Subordinated Debentures Payment of Original Issue Discount, Convertible Junior Subordinated Debentures Deferred tax expense Increase (Decrease) in Deferred Income Taxes Treasury stock Treasury Stock [Member] Equity in net income of subsidiaries Equity in net income of subsidiaries Income (Loss) from Subsidiaries, Net of Tax Income taxes paid Income Taxes Paid Schedule of Recent Accounting and Reporting Developments Accounting Standards Update and Change in Accounting Principle [Table Text Block] Gain (Loss) on Investments by Category [Axis] Debt Security Category [Axis] Credit Union QSR Credit Union Quota Share Reinsurance Agreement [Member] Credit Union Quota Share Reinsurance Agreement Benefit Payments from the Fund Defined Benefit Plan, Benefit Obligation, Benefits Paid Additions to property and equipment Payments to Acquire Property, Plant, and Equipment Company Contributions Defined Benefit Plan, Plan Assets, Contributions by Employer Accumulated Benefit Obligation Defined Benefit Plan, Accumulated Benefit Obligation Total liabilities Liabilities Schedule of Quota Share Reinsurance Agreements Schedule Of Quota Share Reinsurance Agreements [Table Text Block] Schedule Of Quota Share Reinsurance Agreements Current year Current Year Claims and Claims Adjustment Expense Common stock, shares issued (in shares) Common Stock, Shares, Issued Cost and fair value of investments in equity securities Debt Securities, Trading, and Equity Securities, FV-NI [Table Text Block] Total at Year End AOCI in Prior Year AOCI in Current Year Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax Paid claims Primary Default Inventory, Paids Deductions from the primary default inventory resulting from claims being paid, including those charged to a deductible or captive. Actuarial assumptions Defined Benefit Plan, Assumptions [Table Text Block] Entity Address, City or Town Entity Address, City or Town Future earnings period used in determining the expected average rate of earnings Defined Benefit Plan, Future earnings period used in determining the expected average rate of earnings The future earnings period, in years, used in determining the average rate of earnings expected on the classes of funds invested or to be invested to provide for the benefits of the plans. This was then used in selecting the expected long-term rate of return on assets included in the actuarial assumptions used in the valuation of projected benefit obligations, net periodic benefit costs and accumulated postretirement benefit obligation. Loss on debt extinguishment Loss on debt extinguishment Gain (Loss) on Extinguishment of Debt Gross realized losses on sale of fixed income securities Debt Securities, Available-for-sale, Realized Loss Accumulated other comprehensive income (loss) Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Retirement Plan Type [Axis] Retirement Plan Type [Axis] Other Comprehensive Income (Loss) Comprehensive Income (Loss) Note [Text Block] Expected Long-term Return on Plan Assets Used to Determine Net Periodic Benefit Cost (in hundredths) Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets Expected Benefit Payments for the Year Ending: Current plus 1 Defined Benefit Plan, Expected Future Benefit Payment, Year One Retained earnings Retained Earnings (Accumulated Deficit) Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Entity Filer Category Entity Filer Category Adjusted statutory net income dividend payment measurement period Statutory Accounting Practices, Statutory Amount Available for Dividend Payments without Regulatory Approval, Measurement, Dividend Payment Period Statutory Accounting Practices, Statutory Amount Available for Dividend Payments without Regulatory Approval, Measurement, Dividend Payment Period Net realized investment gains (losses) Net realized investment (gains) losses Gain (Loss) on Investments Real estate acquired Real Estate Assets Acquired, Fair Value Disclosure Real Estate Assets Acquired, Fair Value Disclosure Fair Value Estimate of Fair Value Measurement [Member] Statutory policyholders' surplus Statutory Accounting Practices, Statutory Capital and Surplus, Balance Effects of Reinsurance [Line Items] Effects of Reinsurance [Line Items] Amendment Flag Amendment Flag Proceeds from issuance of senior notes Proceeds from Issuance of Long-term Debt Equity Components [Axis] Equity Components [Axis] Fair Value Disclosures [Abstract] Fair Value Disclosures [Abstract] Weighted-average asset allocations of plans (in hundredths) Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage Sales Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales Subtotal Defined Benefit Plan, Net Periodic Benefit Cost Before Amortization and Cost of Settlements The subtotal amount of net periodic benefit cost for defined benefit plans that may include the following components: service cost, interest cost, expected return on plan assets, and other adjustments. Reinsurance recoverable on loss reserves Increase (Decrease) in Reinsurance Recoverable Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Anniversary payment release of the start of the interest deferral to the Alternative Payment Mechanism in lieu of the final maturity of the debentures Anniversary payment release of the start of the interest deferral to the Alternative Payment Mechanism in lieu of the final maturity of the debentures 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. Entity Public Float Entity Public Float Documents Incorporated by Reference Documents Incorporated by Reference [Text Block] 2020 QSR Quota Share Reinsurance Agreement, 2020, One Year [Member] Quota Share Reinsurance Agreement, 2020, One Year 3 months or less (in hundredths) Primary Default Inventory, Three months or less, Percentage The percentage of loans that have been in the primary default inventory for three months or less as of the balance sheet date. Debt Instrument, Redemption, Period Three Debt Instrument, Redemption, Period Three [Member] Investment portfolio: Investments [Abstract] Investments [Abstract] Statement [Line Items] Statement [Line Items] 9% Convertible Junior Subordinated Debentures due 2063 Convertible Junior Debentures at 9% per annum, Due 2063 [Member] Convertible Junior Debentures at 9% per annum, Due 2063 [Member] Total investment portfolio Investments Retirement Plan Type [Domain] Retirement Plan Type [Domain] Amortized Cost SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties, Cost Additional disclosures [Abstract] Additional disclosures [Abstract] Fixed income, available-for-sale, at fair value (amortized cost, 2021 - $6,397,658; 2020 - $6,317,164) Total at end of period Fixed income, available-for-sale Debt Securities, Available-for-sale Deferred insurance policy acquisition costs Increase (Decrease) in Deferred Policy Acquisition Costs Home Re 2018-1 Home Re 2018-1 [Member] Home Re 2018-1 Ltd [Member] Debt Disclosure [Abstract] Debt Disclosure [Abstract] Net Periodic Benefit Cost Defined Benefit Plan, Net Periodic Benefit Cost Before Cost of Settlements and Curtailments The total amount of net periodic benefit cost for defined benefit plans for the period, before the effect of the cost of settlements and curtailments. Periodic benefit costs include the following components: service cost, interest cost, expected return on plan assets, gain (loss), prior service cost or credit, and transition asset or obligation. Reinsurance retention policy Reinsurance Retention Policy [Table Text Block] 2022 QSR Quota Share Reinsurance Agreement, 2022 [Member] Quota Share Reinsurance Agreement, 2022 Benefit Plans Retirement Benefits [Text Block] Fair Value by Asset Class [Axis] Asset Class [Axis] Document Annual Report Document Annual Report Forecast Forecast [Member] Collateral pledged to principal balance of FHLB advance (as a percent) Federal Home Loan Bank Advances, Collateral, Market Value Of Principal, Percent Federal Home Loan Bank Advances, Collateral, Market Value Of Principal, Percent Statutory capital requirements [Abstract] Statutory capital requirements [Abstract] Total income tax benefit (expense) Other Comprehensive Income (Loss), Tax Total assets Total Home Re Assets Assets Plan Name [Domain] Plan Name [Domain] Components of net deferred tax asset [Abstract] Components of Deferred Tax Liabilities [Abstract] Ownership percentage threshold for declaration of due and payable Debt Instrument, Ownership Percentage Threshold, Declaration Of Due And Payable Debt Instrument, Ownership Percentage Threshold, Declaration Of Due And Payable Parent Company Parent Company [Member] Realized losses on fixed income securities related to our intent to sell Debt Securities, Available for Sale, Impairment Charges Intent To Sell No Allowance Previously Recorded Recognized in Net Realized Investment Gains Losses Amount of impairment charges recognized in net realized investment gains (losses) on debt securities where no previous allowance for credit losses has been recorded, but for which the Company intends to sell the securities. Gross realized losses on equity securities Equity Securities, FV-NI, Realized Loss Net Prior Service Cost/(Credit) Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, Prior Service Cost (Credit), before Tax Net Amount Net Amount Premiums Earned, Net Proceeds from sale of equity securities Proceeds From Sale Of Equity Securities The cash inflow associated with the sale of equity securities measured at fair value with change in fair value recognized in net income (FV-NI). 9% Debentures Subordinated Debt Obligations, Fair Value Disclosure Significant Accounting Policies Significant Accounting Policies [Text Block] Risk to capital ratio at end of period Risk to capital ratio at end of period The entity's risk-to-capital ratio as of the end of the reporting period. Cumulative Effect, Period of Adoption [Domain] Cumulative Effect, Period of Adoption [Domain] Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities Schedule of debt Schedule of Debt [Table Text Block] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Table] Fair Value, Recurring and Nonrecurring [Table] Fair Value, Recurring and Nonrecurring [Table] Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Basic earnings per share [Abstract] Earnings Per Share, Basic [Abstract] Weighted average common shares outstanding - basic (in shares) Weighted-average shares - basic (in shares) Weighted Average Number of Shares Outstanding, Basic Diluted (in dollars per share) Diluted income per share (in dollars per share) Earnings Per Share, Diluted Dilutive securities (in shares) Weighted Average Number Diluted Shares Outstanding Adjustment Company Service Cost Defined Benefit Plan, Service Cost Net Actuarial (Gain)/Loss Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Gain (Loss), before Tax Accounting Standards Update [Extensible Enumeration] Accounting Standards Update [Extensible Enumeration] Home Re 2021-1 Home Re 2021-1 [Member] Home Re 2021-1 Comprehensive income Comprehensive Income (Loss), Net of Tax, Attributable to Parent Initial First Layer Retention Reinsurance Retention Policy, Initial Amount Retained Reinsurance Retention Policy, Initial Amount Retained Other comprehensive income Comprehensive Income (Loss) [Table Text Block] Period in which reasonable commercial efforts must begin, maximum Period in which reasonable commercial efforts must begin maximum The maximum period, in business days, after payment of interest on debentures that was not deferred, in which the entity must begin reasonable commercial efforts to sell qualifying securities to unaffiliated persons pursuant to the optional deferral provision under the note agreement(s). Corporate debt securities Corporate Bonds Corporate Debt Securities [Member] Reconciliation of federal statutory income tax rate Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Schedule of total assets of Home Re Entities Schedule of Variable Interest Entities [Table Text Block] Fair value measurements for items measured at fair value Fair Value, Assets Measured on Recurring Basis [Table Text Block] Accumulated other comprehensive income (loss) AOCI Attributable to Parent [Member] Aging of the primary default inventory Aging of Primary Default Inventory [Table Text Block] Tabular disclosure of the aging of the loan primary default inventory. Other assets Other Assets Common stock, shares outstanding (in shares) Common Stock, Shares, Outstanding Change in unrealized gains (losses) of investments Unrealized Gain (Loss) on Investments [Table Text Block] Equity Securities Equity Securities, Investment Summary [Member] Financial Instruments [Domain] Financial Instruments [Domain] Due after five years through ten years Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, after Year 5 Through 10 Federal Home Loan Bank Advance Federal Home Loan Bank, Advances, Branch of FHLB Bank, Amount of Advances Entity Central Index Key Entity Central Index Key Lump sum pension plan benefit payments Defined Benefit Plan Benefits Paid From Fund Lump Sum The amount of lump sum payments made from fund for which participants are entitled under a pension plan, including pension benefits, death benefits, and benefits due on termination of employment. This amount is included in total benefit payments from fund. Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Amount of tax and loss bonds held Tax And Loss Bonds Held Amount of tax and loss bonds held by the reporting entity. Maximum period for which interest payments may be deferred without giving rise to an event of default Maximum period for which interest payments may be deferred without giving rise to an event of default The maximum length of time for which interest payments on the convertible debentures may be deferred without giving rise to an event of default. Number of jurisdictions with risk-to-capital requirements Number of jurisdictions with risk to capital requirements The number of jurisdictions that require a mortgage insurer to maintain a minimum amount of statutory capital relative to the risk in force (or a similar measure) in order for the mortgage insurer to continue to write new business. This is generally referred to as a risk-to-capital requirement. Settlement (Gain)Loss Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Settlement Due in one year or less Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, Year One Maximum permitted risk-to-capital ratio commonly applied Description of Regulatory Capital Requirements under Insurance Regulations Continuous Unrealized Loss Portion, Unrealized Loses [Abstract] Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract] RMBS Residential Mortgage Backed Securities [Member] Condensed Financial Information Disclosure [Abstract] Condensed Financial Information Disclosure [Abstract] Projected Benefit Obligation Benefit Obligation at Beginning of Year Benefit Obligation at End of Year Defined Benefit Plan, Benefit Obligation Insurance Loss Reserves [Abstract] Insurance Loss Reserves [Abstract] Shares repurchased during period (in shares) Treasury Stock, Shares, Acquired Debt Instrument [Line Items] Debt Instrument [Line Items] Trading Symbol Trading Symbol Home Re special purpose insurers Home Re special purpose insurers [Member] Home Re special purpose insurers [Member] SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Abstract] SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Abstract] Audit Information [Abstract] Audit Information [Abstract] International Mutual Funds International Mutual Funds [Member] Investment in a company that brings together money from many people and invests it in stocks, bonds or other assets of international companies. The combined holdings of stocks, bonds or other assets the fund owns are known as its portfolio. Each investor in the fund owns shares, which represent a part of these holdings. Debt issued to cover insurance, term Reinsurance Retention Policy, Debt Issued To Cover Insurance, Term Reinsurance Retention Policy, Debt Issued To Cover Insurance, Term Total Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss Proceeds from sale of fixed income securities available for sale Proceeds from Sale of Debt Securities, Available-for-sale Recognized during year - Net Actuarial (Losses)/Gains Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, before Tax Plan Participants' Contributions Defined Benefit Plan, Plan Assets, Contributions by Plan Participant Significant Accounting Policies [Line Items] Significant Accounting Policies [Line Items] Significant Accounting Policies Reclassification out of Accumulated Other Comprehensive Income [Table] Reclassification out of Accumulated Other Comprehensive Income [Table] Compensation cost Share-based Payment Arrangement, Expense Lifetime loss ratio cap Reinsurance, Quota Share Reinsurance Agreement, Terms, Lifetime Loss Ratio Cap Reinsurance, Quota Share Reinsurance Agreement, Terms, Lifetime Loss Ratio Cap Reclassification out of Accumulated Other Comprehensive Income [Domain] Reclassification out of Accumulated Other Comprehensive Income [Domain] Investments [Domain] Investments [Domain] Liability for Claims and Claims Adjustment Expense [Table] Liability for Claims and Claims Adjustment Expense [Table] Cash and cash equivalents and restricted cash and cash equivalents at beginning of year Cash and cash equivalents and restricted cash and cash equivalents at end of year Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Common stock, par value (in dollars per share) Common Stock, Par or Stated Value Per Share Allowance for Expected Credit Loss Debt Securities, Available-for-sale, Allowance for Credit Loss Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure [Line Items] Minimum and maximum allocation ranges for fixed income securities and equity securities Minimum and Maximum Allocation Ranges for Fixed Income Securities and Equity Securities [Table Text Block] Tabular disclosure of the major categories of plan assets of pension plans and/or other employee benefit plans. This information may include, but is not limited to, the targeted minimum and maximum allocation ranges for fixed income securities and equity securities. Statement of Comprehensive Income [Abstract] Statement of Comprehensive Income [Abstract] All other corporate bonds Other Corporate Bonds [Member] Commodities Commodities Investment [Member] Accounts receivable - affiliates Increase (Decrease) in Accounts Receivable, Related Parties Balance at beginning of period Balance at end of period Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value Amount of required MPP Amount of required MPP The amount of minimum policyholder position (MPP) required by the entity's domiciliary state. Mortgage Guaranty Insurance Corporation Mortgage Guaranty Insurance Corporation [Member] Another company which is controlled, directly or indirectly, by its parent. The usual condition for control is ownership of a majority (over 50%) of the outstanding voting stock. The power to control may also exist with a lesser percentage of ownership, for example, by contract, lease, agreement with other stockholders or by court decree. Purchase of convertible junior subordinated debentures Early Repayment of Subordinated Debt Shareholders' Equity Stockholders' Equity Note Disclosure [Text Block] Measurement Basis [Axis] Measurement Basis [Axis] Fair value measurements Fair Value of Financial Instruments, Policy [Policy Text Block] Auditor Firm ID Auditor Firm ID 5.25% Senior Notes due 2028 Five Point Two Five Percent Senior Notes [Member] Five Point Two Five Percent Senior Notes Share-based compensation arrangement, maximum vesting percent of shares granted Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Maximum Vesting of Target Shares Granted Percent Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Maximum Vesting of Target Shares Granted Percent Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities Defined Benefit Plan, Change in Benefit Obligation [Roll Forward] Defined Benefit Plan, Change in Benefit Obligation [Roll Forward] Portion at Fair Value Measurement Portion at Fair Value Measurement [Member] Change in certain assets and liabilities: Increase (Decrease) in Operating Capital [Abstract] Vested (in dollars per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value Premiums earned, assumed Assumed From Other Companies Assumed Premiums Earned Income taxes receivable Increase (Decrease) in Income Taxes Receivable Threshold for private mortgage insurer eligibility requirements for termination election Reinsurance, Quota Share Reinsurance Agreement, Terms, Threshold For Private Mortgage Insurer Eligibility Requirements For Termination Election Reinsurance, Quota Share Reinsurance Agreement, Terms, Threshold For Private Mortgage Insurer Eligibility Requirements For Termination Election Net Transition Obligation/(Asset) Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Transition Asset (Obligation), before Tax Losses incurred: [Abstract] Losses incurred: [Abstract] Fair Value SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties, Fair Value Discount Rate Used to Determine Net Periodic Benefit Cost (in hundredths) Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Rate of Compensation Increase Used to Determine Net Periodic Benefit Cost (in hundredths) Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase ABS Asset-backed Securities [Member] Reinsurance terminations Reinsurance terminations Decrease in losses paid resulting from cancellations of reinsurance agreements, with no future premium ceded and funds for any incurred but unpaid losses transferred to the entity. Effect of dilutive securities [Abstract] Dilutive Securities, Effect on Basic Earnings Per Share [Abstract] SCHEDULE IV - REINSURANCE SEC Schedule, 12-17, Insurance Companies, Reinsurance [Text Block] Principal amount of notes used in determining conversion rate Principal amount of notes used in determining conversion rate The principal amount of notes used in the determination of the initial conversion rate, which is subject to adjustment. Stockholders' Equity Note [Abstract] Stockholders' Equity Note [Abstract] Extinguishment of debt Extinguishment of Debt, Amount Due after ten years Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, after Year 10 Depreciation and other amortization Depreciation, Amortization and Accretion, Net Reduction in potentially dilutive shares due to debt extinguishment Dilutive securities, Reduction in Potentially Dilutive Shares Due to Debt Extinguishment Reduction in the Company's potentially dilutive shares for computation of earnings per share due to debt extinguishment. Nature of Business Nature of Operations [Text Block] Pension Plan Pension Plan [Member] Cash portion of loss on debt extinguishment Gain Loss on Debt Extinghuishment, Cash Portion Gain Loss on Debt Extinghuishment, Cash Portion Due in one year or less Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, Year One Minimum percentage return should exceed growth in consumer price index annually (in hundredths) Minimum percentage return should exceed growth in consumer price index annually The minimum percentages that return should exceed growth in consumer price index annually. Purchases Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases Current year Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid, Current Year Collateralized loan obligations Collateralized Loan Obligations [Member] Accounting Standards Update 2020-06 [Member]