Trading Arrangements, by Individual Trading Arrangements, by Individual [Table] Senior Notes 6.125 % Due 2034 Senior Notes 6.125 Percent Due 2034 [Member] Senior Notes 6.125 Percent Due 2034 [Member] Denominator: Weighted Average Number of Shares Outstanding, Diluted [Abstract] Trading Arrangement: Trading Arrangement [Axis] Schedule of Deferred Policy Acquisition Costs [Line Items] Policyholder Account Balance [Line Items] Changes in note payable Proceeds from (Repayments of) Notes Payable Ceded earned premiums Ceded Premiums Earned Title of 12(b) Security Title of 12(b) Security Schedule of Available-for-sale Securities [Table] Debt Securities, Available-for-Sale [Table] Document Fiscal Year Focus Document Fiscal Year Focus Adjustment to Compensation, Amount Adjustment to Compensation Amount Policyholder Account Balance Policyholder Account Balance [Table Text Block] Financial Instrument [Axis] Financial Instrument [Axis] Segment Reporting [Abstract] Segment Reporting [Abstract] Investments, available-for-sale, amortized cost basis Total Investments, available-for-sale, amortized cost basis Amortized cost of investment measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). Less reinsurance recoverable at original discount rate Liability for Future Policy Benefit, Reinsurance Recoverable, after Allowance Liability for Future Policy Benefit by Product Segment Liability for Future Policy Benefit, by Product Segment [Table] Fair Value Hierarchy for Assets Measured at Fair Value on a Recurring Basis Fair Value, Assets Measured on Recurring Basis [Table Text Block] Common stock, par value—$2 per share; (authorized: 2026 and 2025—500 million shares; issued: 2026 and 2025—198.3 million shares) Common Stock, Value, Issued Interest expense Interest Expense, Operating and Nonoperating Unearned premiums Increase (Decrease) in Unearned Premiums Depreciation, amortization and other Depreciation, amortization and other Depreciation, amortization and other Employee Retirement Benefits Retirement Benefits [Text Block] Largest equity holdings to total investment portfolio Largest equity holdings to total portfolio Largest equity holdings to total portfolio Separate accounts Separate Account Asset Restatement Determination Date Restatement Determination Date Expected return on plan assets Defined Benefit Plan, Expected Return (Loss) on Plan Assets Derivative, by Nature [Axis] Derivative Instrument [Axis] Other comprehensive income before reclassification, tax Other Comprehensive Income (Loss) before Reclassifications, Tax Differences Between Statutory Income Tax Rate And Effective Income Tax Rate Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Interest accretion rate Liability for Future Policy Benefit, Weighted-Average Interest Accretion Rate Effect of changes in discount rate assumptions AOCI, Liability for Future Policy Benefit, Expected Net Premium, before Tax Investments, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss Investments, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss Amount of accumulated unrealized loss on investment in available for sale security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for 12 months or longer, without allowance for credit loss. Includes beneficial interest in securitized financial asset Current Current Income Tax Expense (Benefit) Amendment Flag Amendment Flag Effect on other comprehensive income, tax Increase (Decrease) in Other Comprehensive Income (Loss), Tax Increase (Decrease) in Other Comprehensive Income (Loss), Tax Effect on other comprehensive income, net of tax Increase (Decrease) in Other Comprehensive Income (Loss), Net of Tax Increase (Decrease) in Other Comprehensive Income (Loss), Net of Tax Entity Common Stock, Shares Outstanding (in shares) Entity Common Stock, Shares Outstanding Other Separate Account, Liability, Increase (Decrease) from Other Change Deferred annuities Deferred Annuities [Member] Deferred Annuities [Member] Fair Values of Deferred Annuities, Structured Settlements and Other Items Fair Value, Liabilities Measured on Recurring and Nonrecurring Basis [Table Text Block] Investment income, net of expenses Total Net Investment Income Increase (decrease) resulting from: Effective Income Tax Rate Reconciliation, Percent [Abstract] Gross unrealized loss Total Unrealized Losses Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax Investment Investment [Text Block] Beginning balance at original discount rate Liability for Future Policy Benefit, Expected Future Policy Benefit, Original Discount Rate, before Cash Flow and Reinsurance Dividend received exclusion Effective Income Tax Rate Reconciliation, Deduction, Dividends, Amount Investments [Domain] Investments [Domain] Change in life policy reserves, reinsurance recoverable and other, before tax Other Comprehensive Income (Loss), Life Policy Reserves, Reinsurance Recoverable and Other, Before Tax Other Comprehensive Income (Loss), Life Policy Reserves, Reinsurance Recoverable and Other, Before Tax Policyholder Account Balance, above Guaranteed Minimum Crediting Rate [Axis] Policyholder Account Balance, above Guaranteed Minimum Crediting Rate [Axis] Current income tax receivable/payable Increase (Decrease) in Deferred Income Taxes Debt Securities, Available-for-sale, Amortized Cost Total Debt Securities, Available-for-Sale, Amortized Cost, after Allowance for Credit Loss Change in pension obligations, before tax Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax Adjustment to Non-PEO NEO Compensation Footnote Adjustment to Non-PEO NEO Compensation Footnote [Text Block] Entity Address, State or Province Entity Address, State or Province Purchase of equity securities Payments to Acquire Equity Securities, FV-NI PEO Total Compensation Amount PEO Total Compensation Amount Common Stock, Par or Stated Value Per Share (in dollars per share) Common Stock, Par or Stated Value Per Share Short-term investments, available-for-sale, accumulated gross unrealized loss, before tax Short-term investments, available-for-sale, accumulated gross unrealized loss, before tax Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in short-term security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale) Basic weighted-average common shares outstanding (in shares) Weighted Average Number of Shares Outstanding, Basic Income Tax Disclosure Income Tax Contingency [Line Items] Retirement Benefits [Abstract] Retirement Benefits [Abstract] Fixed maturity investments, Percentage of amortized costs Fixed maturity investments, Percentage of amortized costs Fixed maturity investments, Percentage of amortized costs. Outstanding Aggregate Erroneous Compensation Amount Outstanding Aggregate Erroneous Compensation Amount Direct earned premiums Direct Premiums Earned Investments, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months Investments, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months Amount of investment in available for sale security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset. Number of Reportable Segments Number of Reportable Segments Deferred policy acquisition costs Increase (Decrease) in Deferred Policy Acquisition Costs Investments Investments [Abstract] 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 Homeowner Homeowner [Member] Homeowner [Member]. Entity Address, City or Town Entity Address, City or Town Liability for Future Policy Benefit, by Product Segment Liability for Future Policy Benefit, by Product Segment [Line Items] Property Casualty Insurance Assumed And Ceded Business [Table] Property Casualty Insurance Premiums Written On Assumed And Ceded Business [Table] Property Casualty Insurance Premiums Written On Assumed And Ceded Business Long-Duration Insurance, Other Long-Duration Insurance, Other [Member] Effect of changes in discount rate assumptions AOCI, Liability for Future Policy Benefit, Expected Future Policy Benefit, before Tax Changes in finance receivables Payments to acquire (proceeds from sale and collection of) finance receivables Payments to acquire (proceeds from sale and collection of) finance receivables Defined Benefit Plan Disclosure Defined Benefit Plan Disclosure [Line Items] Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Award Timing MNPI Disclosure Award Timing MNPI Disclosure [Text Block] Peer Group Total Shareholder Return Amount Peer Group Total Shareholder Return Amount Level 2 Fair Value, Inputs, Level 2 [Member] Total Shareholder Return Vs Peer Group Total Shareholder Return Vs Peer Group [Text Block] Accumulated Other Comprehensive Income [Abstract] Accumulated Other Comprehensive Income [Abstract] Accumulated Other Comprehensive Income [Abstract] Short-term investments, available-for-sale, unrealized loss position, total Short-term investments, available-for-sale, unrealized loss position, total Amount of short-term investment measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position without allowance for credit loss Other comprehensive income (loss) Other comprehensive income (loss) Other Comprehensive Income (Loss), Net of Tax Non-Rule 10b5-1 Arrangement Terminated Non-Rule 10b5-1 Arrangement Terminated [Flag] Net premiums collected Liability for Future Policy Benefit, Expected Net Premium, Net Premium Collected Other Expenses Other Expenses Schedule of Long-term Debt Instruments [Table] Schedule of Long-Term Debt Instruments [Table] Due after ten years Available For Sale Securities Debt Maturities After Ten Years Average Available For Sale Securities Debt Maturities After Ten Years Average Benefits paid Liability for Future Policy Benefit, Expected Future Policy Benefit, Benefit Payment Fee revenues Insurance Commissions and Fees Less investment expenses Investment Income, Investment Expense Treasury stock at cost (2026—44.9 million shares and 2025—42.9 million shares) Treasury Stock, Value Pending Accounting Updates New Accounting Pronouncements, Policy [Policy Text Block] Short-term investments, available-for-sale, continuous unrealized loss position, 12 months or longer, accumulated loss Short-term investments, available-for-sale, continuous unrealized loss position, 12 months or longer, accumulated loss Amount of accumulated unrealized loss on investment in short-term investment measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for 12 months or longer, without allowance for credit loss. Includes beneficial interest in securitized financial asset. Segment Information Segment Reporting [Table Text Block] AOCI, Before Tax Other Comprehensive Income (Loss), before Tax [Abstract] Investment gains and losses, net Gain (Loss) on Investments [Abstract] Matching contributions to 401(k) and Top Hat plans Defined Contribution Plan, Employer Discretionary Contribution Amount Effect on other comprehensive income, net of tax Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent Change in pension obligations, tax Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, Tax Book value Long-Term Debt Policyholder Account Balance, Guaranteed Minimum Crediting Rate Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Table Text Block] 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 Noncash Activities Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Document Period End Date Document Period End Date Changes in: Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity, Increase (Decrease) in Operating Capital [Abstract] Net cash used in investing activities Cash Provided by (Used in) Investing Activity, Including Discontinued Operation Equity Awards Adjustments, Excluding Value Reported in Compensation Table Equity Awards Adjustments, Excluding Value Reported in the Compensation Table [Member] Principal amount of debt Debt Instrument, Face Amount Additional Liability, Long-Duration Insurance, Activity [Table] Additional Liability, Long-Duration Insurance, Activity [Table] Security Exchange Name Security Exchange Name Gross realized losses Debt Securities, Available-for-Sale, Realized Loss United States Geographic Distribution, Domestic [Member] Commercial Auto Line Commercial Auto Segment [Member] Commercial Auto Segment [Member] Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, Tax OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment, Tax Due after ten years Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, after Year 10 Liability for Future Policy Benefit, Adverse Development, Expense Liability for Future Policy Benefit, Adverse Development, Expense Effect on other comprehensive income, tax Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Entity Shell Company Entity Shell Company Consolidation Items [Domain] Consolidation Items [Domain] Other Effective Income Tax Rate Reconciliation, Other Adjustments, Amount Pension contributions Payment for Pension Benefits 12 months or more, Fair Value Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer Statement of Comprehensive Income [Abstract] Statement of Comprehensive Income [Abstract] Life policy reserves: Life Policy Reserves [Member] Life Policy Reserves [Member] Fair Value of Life Policy Loans Fair Value, Assets Measured on Recurring and Nonrecurring Basis [Table Text Block] Net Income (Loss) Per Common Share Earnings Per Share [Text Block] Name Outstanding Recovery, Individual Name Number of fixed-maturity securities in continuous unrealized loss position and below 70 percent of amortized cost Number Of Securities Continuous Unrealized Loss Position and Below 70 Percent of Amortized Cost Number Of Securities Continuous Unrealized Loss Position and Below 70 Percent of Amortized Cost Per Common Share Earnings Per Share [Abstract] Award Timing, How MNPI Considered Award Timing, How MNPI Considered [Text Block] Document Fiscal Period Focus Document Fiscal Period Focus Peer Group Issuers, Footnote Peer Group Issuers, Footnote [Text Block] Total liabilities Liabilities Insurance reserves Liability for Future Policy Benefits and Unpaid Claims and Claims Adjustment Expense [Abstract] Trading Symbol Trading Symbol Deferred Costs [Abstract] Deferred Costs [Abstract] Investment in building and equipment Payments to Acquire Property, Plant, and Equipment Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year [Member] Reclassification adjustment, tax Reclassification from Accumulated Other Comprehensive Income, Current Period, Tax Reclassification from Accumulated Other Comprehensive Income, Current Period, Tax Pension Adjustments Prior Service Cost Pension Adjustments Prior Service Cost [Member] Life Insurance Assumed and Ceded Business Life Insurance Assumed And Ceded Business Table [Table Text Block] Life Insurance Assumed And Ceded Business Table [Text Block] Policyholder Account Balance [Abstract] Company Selected Measure Name Company Selected Measure Name Undiscounted expected future benefit payments Liability for Future Policy Benefit, Expected Future Policy Benefit, Undiscounted, before Reinsurance Purchase of fixed maturities Payments to Acquire Debt Securities, Available-for-Sale Income Tax Disclosure [Abstract] Income Tax Disclosure [Abstract] Investment contract reserves: Investment contract reserves [Member] Investment contract reserves [Member] Change in unrealized gains and losses on investments, net of tax (benefit) of $16, $6, $(30) and $20, respectively OCI, Debt Securities, Available-for-Sale, Gain (Loss), after Adjustment and Tax Effect of changes in cash flow assumptions Additional Liability, Long-Duration Insurance, Cumulative Increase (Decrease) from Cash Flow Change AOCI on Pension Obligations Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] Equity Securities, FV-NI, Cost Equity Securities, FV-NI, Cost Fixed maturities Debt Securities [Member] Investments, Available-for-Sale, Unrealized Loss Position, Accumulated Loss Investments, Available-for-Sale, Unrealized Loss Position, Accumulated Loss Amount of accumulated unrealized loss on investment in available for sale security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position, without allowance for credit loss. Includes beneficial interest in securitized financial asset Reserve for loss and loss expenses Gross loss and loss expense reserves, beginning of period Gross loss and loss expense reserves, end of period Liability for Claims and Claims Adjustment Expense Cash Flows From Operating Activities Cash Provided by (Used in) Operating Activity, Including Discontinued Operation [Abstract] Schedule of Deferred Policy Acquisition Costs Schedule of Deferred Policy Acquisition Costs [Line Items] [Line Items] for Schedule of Deferred Policy Acquisition Costs [Table] Compensation Amount Outstanding Recovery Compensation Amount Individual: Individual [Axis] Diluted weighted-average shares Weighted Average Number of Shares Outstanding, Diluted Whole Life Insurance Whole Life Insurance [Member] Entity Emerging Growth Company Entity Emerging Growth Company Equity Valuation Assumption Difference, Footnote Equity Valuation Assumption Difference, Footnote [Text Block] Underlying Security Market Price Change Underlying Security Market Price Change, Percent Operating loss carryforwards Operating Loss Carryforwards Life Policy and Investment Contract Reserves Long-Duration Insurance Contracts Disclosure [Text Block] Policyholder Account Balance, Guaranteed Minimum Crediting Rate, Range from 0300 to 0399 Policyholder Account Balance, Guaranteed Minimum Crediting Rate, Range from 0300 to 0399 [Member] Outstanding principle and interest for life policy loans Outstanding principle and interest for life policy loans Outstanding principle and interest for life policy loans Investment income receivable Accrued Investment Income Receivable Award Timing Predetermined Award Timing Predetermined [Flag] Gross premiums Liability for Future Policy Benefit, Gross Premium Income Treasury Stock Treasury Stock, Common [Member] Debt Securities, Available-for-sale Debt Securities, Available-for-Sale [Line Items] Adjustment To PEO Compensation, Footnote Adjustment To PEO Compensation, Footnote [Text Block] Share-based compensation APIC, Share-Based Payment Arrangement, Increase for Cost Recognition Insurance losses and contract holders' benefits Incurred loss and loss expenses Policyholder Benefits and Claims Incurred, Net Level 1 Fair Value, Inputs, Level 1 [Member] Net loss and loss expense reserves, beginning of period Net loss and loss expense reserves, end of period Liability for Unpaid Claims and Claims Adjustment Expense, Net Provision for income taxes Effective Income Tax Rate Reconciliation, Percent Reinsurance for Insurance Companies, by Product Segment SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items] Investment gains and losses, net Gain (Loss) on Sale of Investments Effect of stock-based awards (in shares) Incremental Common Shares Attributable to Dilutive Effect of Share-Based Payment Arrangements Investments, Unrealized Loss Position Debt Securities, Available-for-Sale, Unrealized Loss Position, Fair Value [Table] All Executive Categories All Executive Categories [Member] Short-term investments, available-for-sale, amortized cost basis Short-term investments, available-for-sale, amortized cost basis Amortized cost of short-term investments measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). Pension Adjustments Service Cost Pension Adjustments Service Cost [Member] Schedule of Earnings Per Share, Basic and Diluted, by Common Class [Table] Schedule Of Earnings Per Share Basic And Diluted By Common Class [Table] Schedule of Earnings Per Share, Basic and Diluted, by Common Class [Table] Amortization of pension actuarial gain and prior service cost, net of tax (benefit) of $0, $0, $0 and $0, respectively Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, after Tax Fair value of senior debt Long-Term Debt, Fair Value Investments, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss Investments, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss Amount of accumulated unrealized loss on investment in available for sale security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset Ceded incurred loss and loss expenses Ceded contract holders' benefits incurred Policyholder Benefits and Claims Incurred, Ceded Short-term investments, available-for-sale, continuous unrealized loss position, 12 months or longer Short-term investments, available-for-sale, continuous unrealized loss position, 12 months or longer Amount of short-term investment measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset. Term Life Insurance Term Life Insurance [Member] Short-term investments, available-for-sale, unrealized loss position, accumulated loss Short-term investments, available-for-sale, unrealized loss position, accumulated loss Amount of accumulated unrealized loss on investment in short-term investment measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position, without allowance for credit loss. Includes beneficial interest in securitized financial asset Deferred Policy Acquisition Costs And Asset Reconciliation, Including the Amortized Deferred Policy Acquisition Costs Deferred Policy Acquisition Costs [Table Text Block] Due in one year or less Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, Year One Calculations For Basic And Diluted Earnings Per Share Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Policyholder Account Balance, Guaranteed Minimum Crediting Rate Range [Domain] Policyholder Account Balance, Guaranteed Minimum Crediting Rate Range [Domain] Fair Value Disclosures [Abstract] Fair Value Disclosures [Abstract] Contract holders' funds withdrawn Withdrawal from Contract Holders Funds Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Capitalized deferred policy acquisition costs Deferred Policy Acquisition Cost, Capitalization Segment Information Segment Reporting [Text Block] Investment Type [Axis] Investment Type [Axis] Payment of cash dividends to shareholders Payments of Ordinary Dividends, Common Stock Expiration Date Trading Arrangement Expiration Date Net change in cash and cash equivalents Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Period Increase (Decrease), Excluding Exchange Rate Effect, Including Discontinued Operation Change in short-term investments Change in short-term investments Net Change in short-term investments Additional Liability, Long-Duration Insurance [Line Items] Additional Liability, Long-Duration Insurance [Line Items] Fair value of asset Investments, Fair Value Disclosure Discount Rate Assumption Changes included in Impact of flooring at Cohort Level Discount Rate Assumption Changes included in Impact of flooring at Cohort Level Discount Rate Assumption Changes included in Impact of flooring at Cohort Level Liabilities Liabilities [Abstract] Accumulated Other Comprehensive Income Details Reclassification Out of Accumulated Other Comprehensive Income [Line Items] [Line Items] for Reclassification Out of Accumulated Other Comprehensive Income [Table] Adjusted beginning of period balance Ending balance at original discount rate Liability for Future Policy Benefit, Expected Future Benefit, Original Discount Rate, before Reinsurance, after Cash Flow Change Deferred Fixed Annuity Deferred Fixed Annuity [Member] Non-Rule 10b5-1 Arrangement Adopted Non-Rule 10b5-1 Arrangement Adopted [Flag] Cash and Cash Equivalents, Fair Value Disclosure Cash and Cash Equivalents, Fair Value Disclosure Premiums received Policyholder Account Balance, Premium Received Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table [Member] Amortized cost Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Amortized Cost [Abstract] Other liabilities Other Liabilities Net periodic benefit cost Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Aggregate Pension Adjustments Service Cost Aggregate Pension Adjustments Service Cost [Member] Deferred Policy Acquisition Cost [Table] Deferred Policy Acquisition Cost [Table] Common Stock, Shares Authorized (in shares) Common Stock, Shares Authorized Earnings (loss) per share: Earnings Per Share Reconciliation [Abstract] Due in one year or less Available For Sale Securities Debt Maturities Within One Year Average Available For Sale Securities Debt Maturities Within One Year Average Gross realized gains Debt Securities, Available-for-Sale, Realized Gain Due after ten years Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, after Year 10 Schedule of Carrying Values and Estimated Fair Values of Debt Instruments [Table Text Block] Schedule of Carrying Values and Estimated Fair Values of Debt Instruments [Table Text Block] Exercise Price Award Exercise Price Cash Flows From Investing Activities Cash Provided by (Used in) Investing Activity, Including Discontinued Operation [Abstract] Segment Reporting Segment Reporting [Line Items] AOCI, Tax Accumulated Other Comprehensive Income Loss Tax [Abstract] Accumulated Other Comprehensive Income (Loss), Tax [Abstract] Document Quarterly Report Document Quarterly Report Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested [Member] Segments [Domain] Segments [Domain] Investments, Unrealized Loss Position Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items] States, municipalities and political subdivisions US States and Political Subdivisions Debt Securities [Member] Sale, call or maturity of fixed maturities Proceeds from Sale of Debt Securities, Available-for-Sale Income ( Loss) Before Income Taxes Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest Prior accident years Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid, Prior Years Finance receivable Financing Receivable, after Allowance for Credit Loss Awards Close in Time to MNPI Disclosures, Table Awards Close in Time to MNPI Disclosures [Table Text Block] Equity Component [Domain] Equity Component [Domain] Deferred policy acquisition costs Deferred policy acquisition costs asset, beginning of period Deferred policy acquisition costs asset, end of period Deferred Policy Acquisition Cost PEO Actually Paid Compensation Amount PEO Actually Paid Compensation Amount Structured Settlement Annuity Structured Settlement Annuity [Member] Fair value of life policy loans Loans Receivable, Fair Value Disclosure Benefits and Expenses Benefits, Losses and Expenses [Abstract] Senior Debentures 6.920% Due 2028 Senior Debentures Six Point Nine Two Percent Due Twenty Twenty Eight [Member] Senior Debentures 6.92 Percent Due 2028 [Member] Adoption Date Trading Arrangement Adoption Date Policyholder Account Balance, above Guaranteed Minimum Crediting Rate [Domain] Policyholder Account Balance, above Guaranteed Minimum Crediting Rate [Domain] Commercial Insurance Commercial Lines Insurance [Member] Commercial Lines Insurance Premium Receivable, Allowance for Credit Loss Premium Receivable, Allowance for Credit Loss Summary of Consolidated Property Casualty Loss and Loss Expense Reserves [Roll Forward] Liability for Claims and Claims Adjustment Expense [Line Items] Interest rate Debt Instrument, Interest Rate, Stated Percentage Dividends declared Dividends, Common Stock, Cash Total shareholders' equity Beginning balance Ending balance Equity, Attributable to Parent Net liability for future policy benefits: Net Liability for Future Policy Benefits [Roll Forward] Net Liability for Future Policy Benefits Assumed incurred loss and loss expenses Policyholder Benefits and Claims Incurred, Assumed Assets Assets [Abstract] Other Other Realized Investment Gains Losses Net This item represents realized investment gains (losses) included in earnings for the period excluding those relating to other than temporary impairment losses on investments in debt securities. Includes realized investment gains and losses generated from the sale of debt securities, equity securities, investments in joint ventures and limited partnerships and from other than temporary impairments on investments other than debt securities. Also includes realized investment gains and losses are generated from prepayment premiums, recoveries of principal on previously impaired securities, provisions for losses on commercial mortgage and other loans, and fair value changes on embedded derivatives and derivatives that do not qualify for hedge accounting treatment, except those derivatives used in the Company's capacity as a broker or dealer. Title Trading Arrangement, Individual Title Forgone Recovery due to Disqualification of Tax Benefits, Amount Forgone Recovery due to Disqualification of Tax Benefits, Amount United Kingdom Geographic Distribution, Foreign [Member] Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Table] Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Table] Other invested assets Other Investments Direct written premiums Direct Premiums Written Accounting Policies [Abstract] Accounting Policies [Abstract] Restatement does not require Recovery Restatement Does Not Require Recovery [Text Block] Insider Trading Policies and Procedures [Line Items] Surrenders and withdrawals Policyholder Account Balance, Surrender and Withdrawal Other Proceeds from (Payment for) Other Financing Activity Insider Trading Policies and Procedures Adopted Insider Trading Policies and Procedures Adopted [Flag] Deferred Deferred income tax expense Deferred Income Tax Expense (Benefit) Other nontaxable or nondeductible items Effective Income Tax Rate Reconciliation, Nondeductible Expense, Other, Amount Current accident year Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid, Current Year Total incurred Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims Issuances Liability for Future Policy Benefit, Expected Net Premium, Issuance Business Combination [Domain] Business Combination [Domain] Commitments and Contingent Liabilities Commitments and Contingencies Disclosure [Text Block] Compensation Actually Paid vs. Net Income Compensation Actually Paid vs. Net Income [Text Block] Number of anti-dilutive stock-based awards (in shares) Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Nonvested shares Restricted Stock Units (RSUs) [Member] Policy charges Policyholder Account Balance, Policy Charge Senior Debentures 6.900% Due 2028 Senior Debentures Six Point Nine Percent Due Twenty Twenty Eight [Member] Senior Debentures 6.9 Percent Due 2028 [Member] Entity Central Index Key Entity Central Index Key Premiums Written, Net [Abstract] Premiums Written, Net [Abstract] Property, Plant, and Equipment, Accumulated Depreciation, Depletion, and Amortization Property, Plant, and Equipment, Accumulated Depreciation, Depletion, and Amortization Weighted average crediting rate Policyholder Account Balance, Weighted Average Crediting Rate Paid-in capital Additional Paid in Capital, Common Stock All Adjustments to Compensation All Adjustments to Compensation [Member] Corporate, Non-Segment Segment Reporting, Reconciling Item, Corporate Nonsegment [Member] Business Combination [Axis] Business Combination [Axis] Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year [Member] Net cash provided by operating activities Cash Provided by (Used in) Operating Activity, Including Discontinued Operation Tax at statutory rate Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount Policyholder Account Balance, above Guaranteed Minimum Crediting Rate, Range from 0001 to 0050 Policyholder Account Balance, above Guaranteed Minimum Crediting Rate, Range from 0001 to 0050 [Member] Life policy and investment contract reserves Net life policy reserves Liability for Future Policy Benefit, before Reinsurance Prior accident years Prior Year Claims and Claims Adjustment Expense Other Stockholders' Equity, Other Other comprehensive income before reclassification, net of tax Other Comprehensive Income (Loss), before Reclassifications, Net of Tax Income Statement [Abstract] Income Statement [Abstract] Shareholders' Equity Equity, Attributable to Parent [Abstract] Document Transition Report Document Transition Report Weighted-average duration of the net life policy reserves in years Liability for Future Policy Benefit, Weighted-Average Duration Universal life Universal Life [Member] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Investment gains and losses, net Total Gain (Loss) on Investments Liability for Claims and Claims Adjustment Expense [Table] Liability for Claims and Claims Adjustment Expense [Table] Commercial Property Line Commercial Property Segment [Member] Commercial Property Segment [Member] Stock Appreciation Rights (SARs) Stock Appreciation Rights (SARs) [Member] Separate accounts Balance, beginning of period Balance, end of period Separate Account, Liability City Area Code City Area Code Balance, end of period before shadow reserve adjustments Additional Liability, Long-Duration Insurance, before Reinsurance, after Discount Rate Change Change in Life Policy Reserves, Reinsurance Recoverable and Other, Tax Other Comprehensive Income (Loss), Life Policy Reserves, Reinsurance Recoverable and Other, Tax Other Comprehensive Income (Loss), Life Policy Reserves, Reinsurance Recoverable and Other, Tax SEC Schedule, 12-18, Supplemental Information, Property-Casualty Insurance Underwriters [Table] SEC Schedule, 12-18, Supplemental Information, Property-Casualty Insurance Underwriters [Table] Accumulated Other Comprehensive Income Summary of AOCI AOCI Attributable to Parent [Member] Other Comprehensive Income Loss, Pension And Other Postretirement Benefit Plans, Net Actuarial Loss And Prior Service Cost Arising During Period, Tax Other Comprehensive Income Loss, Pension And Other Postretirement Benefit Plans, Net Actuarial Loss And Prior Service Cost Arising During Period, Tax Other Comprehensive Income Loss, Pension And Other Postretirement Benefit Plans, Net Actuarial Loss And Prior Service Cost Arising During Period, Tax All Individuals All Individuals [Member] Total Debt Instrument, Fair Value Disclosure Dividend received exclusion, Percent Effective Income Tax Rate Reconciliation, Deduction, Dividend, Percent Name Forgone Recovery, Individual Name Benefit payments Separate Account, Liability, Benefit Payment Top Hat savings plan mutual funds and common equity (included in Other assets) Other Investment Not Readily Marketable, Fair Value Shares acquired - share-based compensation plans Shares Acquired During Period, Value, Employee Share-Based Compensation Plans Shares Acquired During Period, Value, Employee Share-Based Compensation Plans Non-GAAP Measure Description Non-GAAP Measure Description [Text Block] Debt issuance year Debt Instrument Issuance Year Debt instrument issuance year. Total non-service benefit Defined Benefit Plan, Non-Service Cost (Benefit) Defined Benefit Plan, Non-Service Cost (Benefit) Consolidated Property And Casualty Insurance Consolidated Property And Casualty Insurance [Member] Consolidated Property And Casualty Insurance Statement Statement [Line Items] Total assets Assets Assets Schedule of Defined Benefit Plans Disclosures [Table] Defined Benefit Plan [Table] Investments, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer Investments, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer Amount of investment in available for sale security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset Industry Sector [Axis] Category [Axis] Industry Sector [Axis] Investment Segment Investment Segment of CINF [Member] Investment segment of the company Additional Liability, Long-Duration Insurance Additional Liability, Long-Duration Insurance [Table Text Block] Equipment acquired under finance lease obligations Lease Obligation Incurred Schedule of Deferred Policy Acquisition Costs Policyholder Account Balance [Table] Liability for Future Policy Benefit Activity Liability for Future Policy Benefit Activity [Table] Fair value of largest single common stock holding Largest Single Common Stock Holding Largest Single Common Stock Holding Operating Segments Operating Segments [Member] Gross unrealized gain Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax % of fair value Available-for-sale Securities, Debt Maturities, Average, Percent [Abstract] Available-for-sale Securities, Debt Maturities, Average, Percent [Abstract] Other comprehensive income before reclassification, before tax Other Comprehensive Income (Loss), before Reclassifications, before Tax Other assets Increase (Decrease) in Other Operating Assets Balance, beginning of period before shadow reserve adjustments Additional Liability, Long-Duration Insurance, Original Discount Rate, before Cash Flow and Reinsurance Net life policy reserves, after reinsurance recoverable Liability for Future Policy Benefit, after Reinsurance PEO PEO [Member] Due after five years through ten years Available For Sale Securities Debt Maturities After Five Through Ten Years Average Available For Sale Securities Debt Maturities After Five Through Ten Years Average Investments, Available-for-Sale Total Investments, Available-for-Sale Amount of investment measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). Retirement Plan Type [Axis] Retirement Plan Type [Axis] Forgone Recovery due to Violation of Home Country Law, Amount Forgone Recovery due to Violation of Home Country Law, Amount Share-based awards (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercises in Period Liability for Future Policy Benefit, Activity Liability for Future Policy Benefit, Activity [Line Items] Short-term investments, available-for-sale, accumulated gross unrealized gain, before tax Short-term investments, available-for-sale, accumulated gross unrealized gain, before tax Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI), on investment in short-term security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). Total investments Investments Largest equity holdings to total equity portfolio largest equity holdings to total equity portfolio largest equity holdings to total equity portfolio Due in one year or less Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, Year One Retained Earnings Retained Earnings [Member] AOCI on Net Unrecognized Investment Gain (Loss) AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-Sale, Parent [Member] Erroneously Awarded Compensation Recovery Erroneously Awarded Compensation Recovery [Table] Beginning Balance (in shares) Ending Balance (in shares) Common Stock, Shares, Outstanding Award Timing Disclosures [Line Items] Net income — diluted Diluted (in USD per share) Earnings Per Share, Diluted Net other additional liability, after reinsurance recoverable Additional Liability, Long-Duration Insurance, after Reinsurance Entity Current Reporting Status Entity Current Reporting Status Net cash used in financing activities Cash Provided by (Used in) Financing Activity, Including Discontinued Operation Total Shareholder Return Amount Total Shareholder Return Amount Effect on other comprehensive income, before tax Increase (Decrease) in Other Comprehensive Income (Loss), before Tax Increase (Decrease) in Other Comprehensive Income (Loss), before Tax Unrealized gains and losses on securities still held, net Unrealized Gain (Loss) on Investments Reinsurance for Insurance Companies, by Product Segment SEC Schedule, 12-17, Insurance Companies, Reinsurance [Table] Adjustments to reconcile net income to net cash provided by operating activities: Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity [Abstract] Investments, Available-for-Sale, Accumulated Gross Unrealized Loss Before Tax Investments, Available-for-Sale, Accumulated Gross Unrealized Loss Before Tax Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). Cash Flows From Financing Activities Cash Provided by (Used in) Financing Activity, Including Discontinued Operation [Abstract] Land, building and equipment, net, for company use (accumulated depreciation: 2026—$376; 2025—$367) Property, Plant, and Equipment, after Accumulated Depreciation, Depletion, and Amortization Other Effective Income Tax Rate Reconciliation, Other Adjustments, Percent Interest cost Defined Benefit Plan, Interest Cost Excess death benefits Additional Liability, Long-Duration Insurance, Benefit Payment Financial Instruments [Domain] Financial Instruments [Domain] Policyholder Account Balance, above Guaranteed Minimum Crediting Rate, Range from 0051 to 0150 Policyholder Account Balance, above Guaranteed Minimum Crediting Rate, Range from 0051 to 0150 [Member] Prepaid reinsurance premiums Prepaid Reinsurance Premiums Life policy and investment contract reserves Increase (Decrease) in Future Policy Benefit Reserves Other revenues Other Other Income Share-based awards Stock Issued During Period, Value, Stock Options Exercised Equity Awards Adjustments, Footnote Equity Awards Adjustments, Footnote [Text Block] Liabilities Related to Investment Contracts, Fair Value Disclosure Liabilities Related to Investment Contracts, Fair Value Disclosure Underlying Securities Award Underlying Securities Amount Net amount at risk Policyholder Account Balance, Net Amount at Risk Beginning balance at original discount rate Liability for Future Policy Benefit, Expected Net Premium, Original Discount Rate, before Cash Flow and Reinsurance Workers' Compensation Line Workers Compensation [Member] Workers' Compensation [Member] Effect of changes in interest rate assumptions Additional Liability, Long-Duration Insurance, Increase (Decrease) from Discount Rate Change Assumed written premiums Assumed Premiums Written Effect of actual variances from expected experience Additional Liability, Long-Duration Insurance, Cumulative Increase (Decrease) of Actual Variance from Expected Experience Separate Account, Liability Separate Account, Liability [Line Items] Nonredeemable preferred equities Preferred Stock [Member] Change in other invested assets, net Payment for (Proceeds from) Other Investing Activity AOCI, before tax, beginning of period AOCI, before tax, end of period AOCI Including Portion Attributable to Noncontrolling Interest, before Tax Schedule of Gain (Loss) on Securities Schedule of Gain (Loss) on Securities [Table] Undiscounted expected future gross premiums Liability for Future Policy Benefit, Expected Future Gross Premium, Undiscounted, before Reinsurance Segment Reporting Segment Reporting [Table] Separate accounts taxable fixed maturities Taxable Fixed Maturities [Member] Taxable Fixed Maturities [Member] Provision for Income Taxes Income Tax Expense (Benefit), Continuing Operations [Abstract] Other nontaxable or nondeductible items, Percent Effective Income Tax Rate Reconciliation, Nondeductible Expense, Other, Percent Policyholder Account Balance, Guaranteed Minimum Crediting Rate, Range from 0200 to 0299 Policyholder Account Balance, Guaranteed Minimum Crediting Rate, Range from 0200 to 0299 [Member] Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] All Trading Arrangements All Trading Arrangements [Member] Total Available For Sale Securities Debt Maturities Average Available For Sale Securities Debt Maturities Average Less than 12 months Fair Value Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months Other Performance Measure, Amount Other Performance Measure, Amount Award Timing MNPI Considered Award Timing MNPI Considered [Flag] Interest credited to contract holders Interest Credited to Policy Owner Account Balance, beginning of period Balance, end of period Additional Liability, Long-Duration Insurance, before Reinsurance, after Discount Rate Change, after Shadow Reserve Adjustment Additional Liability, Long-Duration Insurance, before Reinsurance, after Discount Rate Change, after Shadow Reserve Adjustment Current Fiscal Year End Date Current Fiscal Year End Date Current discount rate Liability for Future Policy Benefit, Current Weighted-Average Discount Rate Number of fixed-maturity securities in a total unrealized loss position Number Of Securities Continuous Unrealized Loss Position Number Of Securities Continuous Unrealized Loss Position Dividends Investment Income, Dividend Non-PEO NEO Average Total Compensation Amount Non-PEO NEO Average Total Compensation Amount Change in unrealized gains, net, on investments available for sale, before tax Other Comprehensive Income (Loss), Available-for-sale Securities and Other Assets Adjustment, before Tax Other Comprehensive Income (Loss), Available-for-sale Securities and Other Assets Adjustment, before Tax SEC Schedule, 12-18, Supplemental Information, Property-Casualty Insurance Underwriters SEC Schedule, 12-18, Supplemental Information, Property-Casualty Insurance Underwriters [Line Items] Fair value of note payable Notes Payable, Fair Value Disclosure Foreign government Debt Security, Government, Non-US [Member] Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year [Member] Dividends declared per common share (in dollars per share) Common Stock, Dividends, Per Share, Declared Entity File Number Entity File Number Rule 10b5-1 Arrangement Adopted Rule 10b5-1 Arrangement Adopted [Flag] Service cost Defined Benefit Plan, Service Cost Investments Classified by Contractual Maturity Date Investments Classified by Contractual Maturity Date [Table Text Block] Equity securities Equity Securities [Member] Corporate Corporate Bond Securities [Member] Consolidated Property Casualty Loss And Loss Expense Reserves Schedule of Liability for Unpaid Claims and Claims Adjustment Expense [Table Text Block] Recovery of Erroneously Awarded Compensation Disclosure [Line Items] Common Stock, Shares, Issued (in shares) Common Stock, Shares, Issued Measure: Measure [Axis] Policyholder Account Balance, at Guaranteed Minimum Crediting Rate Policyholder Account Balance, at Guaranteed Minimum Crediting Rate [Member] Senior Debentures 6.920 % Due 2028 Senior Debentures 6.92 Percent Due 2028 [Member] Senior Debentures 6.92 Percent Due 2028 [Member] Separate Account, Liability Separate Account, Liability [Table Text Block] Treasury Stock, Common, Shares (in shares) Treasury Stock, Common, Shares Earned premiums Earned premiums Premiums Earned, Net Allowance for credit loss on fixed-maturity Debt Securities, Available-for-Sale, Allowance for Credit Loss 12 months or longer, Unrealized Loss Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss Accumulated Other Comprehensive Income Comprehensive Income (Loss) Note [Text Block] Equity Components [Axis] Equity Components [Axis] Other operating expenses Other Cost and Expense, Operating Effect of changes in cash flow assumptions Liability for Future Policy Benefit, Expected Net Premium, Cumulative Increase (Decrease) from Cash Flow Change Product and Service [Domain] Product and Service [Domain] Fair Value, Assets and Liabilities Measured on Recurring Basis [Table] Fair Value Assets And Liabilities Measured On Recurring Basis [Table] Fair Value, Assets and Liabilities Measured on Recurring Basis [Table] Income taxes paid Income Tax Paid, after Refund Received Deferred tax assets valuation allowance Deferred Tax Assets, Valuation Allowance Entity Interactive Data Current Entity Interactive Data Current Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract] Compensation Actually Paid vs. Other Measure Compensation Actually Paid vs. Other Measure [Text Block] Liability for Future Policy Benefit, after Reinsurance [Abstract] Liability for Future Policy Benefit, after Reinsurance [Abstract] 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 Fair value Debt Securities, Available-for-Sale, Maturity, Allocated and Single Maturity Date, Fair Value [Abstract] Schedule of Earnings Per Share, Basic and Diluted, by Common Class Schedule Of Earnings Per Share Basic And Diluted By Common Class [Line Items] Schedule of Earnings Per Share, Basic and Diluted, by Common Class [Line Items] Entity Small Business Entity Small Business Net written premiums Increase (Decrease) in Property and Casualty Insurance Liabilities Comprehensive Income Comprehensive Income (Loss), Net of Tax, Attributable to Parent Unearned premiums Unearned Premiums Termination Date Trading Arrangement Termination Date Schedule of Deferred Policy Acquisition Costs Schedule of Deferred Policy Acquisition Costs [Table] Schedule of Deferred Policy Acquisition Costs [Table] Fair Value, Recurring and Nonrecurring [Table] Fair Value, Recurring and Nonrecurring [Table] Less reinsurance recoverable, end of period Additional Liability, Long-Duration Insurance, Reinsurance Recoverable, after Allowance Other assets and other liabilities Liabilities Assumed Tax at statutory rate, percentage Tax at statutory rate Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Compensation Actually Paid vs. Total Shareholder Return Compensation Actually Paid vs. Total Shareholder Return [Text Block] Change in pension obligations, net of tax Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax MNPI Disclosure Timed for Compensation Value MNPI Disclosure Timed for Compensation Value [Flag] Current accident year Current Year Claims and Claims Adjustment Expense Government-sponsored enterprises US Government-sponsored Enterprises Debt Securities [Member] Equity Securities at Fair Value Marketable Securities Interest accrual Liability for Future Policy Benefit, Expected Future Policy Benefit, Interest Expense Document Type Document Type Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value as of Grant Date Award Grant Date Fair Value Fair Value and Unrealized Losses by Investment Category and By the Duration of the Securities' Continuous Unrealized Loss Position Debt Securities, Available-for-Sale, Unrealized Loss Position, Fair Value [Table Text Block] Accounting Policies Significant Accounting Policies [Text Block] Pay vs Performance Disclosure, Table Pay vs Performance [Table Text Block] Arrangement Duration Trading Arrangement Duration Deferred Policy Acquisition Cost [Line Items] Deferred Policy Acquisition Cost [Line Items] Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Local Phone Number Local Phone Number Consolidation Items [Axis] Consolidation Items [Axis] Deferred income tax Deferred Tax Liabilities, Gross Entity Address, Postal Zip Code Entity Address, Postal Zip Code Entity Registrant Name Entity Registrant Name Less than 12 Months, Unrealized Loss Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss Reinsurance recoverable Reinsurance Recoverable Reinsurance Recoverable Effect on other comprehensive income, before tax Other Comprehensive Income (Loss), before Tax, Portion Attributable to Parent Short-term investments, available-for-sale, continuous unrealized loss position, less than 12 months Short-term investments, available-for-sale, continuous unrealized loss position, less than 12 months Amount of short-term investment measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset Income Before Income Taxes Total income (loss) before income tax Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Insider Trading Policies and Procedures Not Adopted Insider Trading Policies and Procedures Not Adopted [Text Block] Commitments and contingent liabilities (Note 12) Commitments and Contingencies Total revenues Total revenues Revenues Underwriting, acquisition and insurance expenses Underwriting Acquisition And Insurance Expenses Amount of commissions, insurance operating expenses, increase in deferred acquisition costs and taxes, licenses and fees. Change in Life Policy Reserves, Reinsurance Recoverable and Other, Net of Tax Other Comprehensive Income (Loss), Life Policy Reserves, Reinsurance Recoverable and Other, Net of Tax Other Comprehensive Income (Loss), Life Policy Reserves, Reinsurance Recoverable and Other, Net of Tax Changed Peer Group, Footnote Changed Peer Group, Footnote [Text Block] Tax-exempt income from municipal bonds Effective Income Tax Rate Reconciliation, Tax Exempt Income, Amount Gain (Loss) on Securities Gain (Loss) on Securities [Line Items] Income Tax Contingency [Table] Income Tax Contingency [Table] Forgone Recovery due to Expense of Enforcement, Amount Forgone Recovery due to Expense of Enforcement, Amount Balance, beginning of period Balance, end of period Policyholder Account Balance Structured settlements Structured Finance [Member] Due after one year through five years Available For Sale Securities Debt Maturities After One Through Five Years Average Available For Sale Securities Debt Maturities After One Through Five Years Average Executive Category: Executive Category [Axis] Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items] Policyholder Account Balance, Guaranteed Minimum Crediting Rate [Line Items] Reinsurance Reinsurance [Text Block] Movement Analysis of Deferred Policy Acquisition Costs Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward] Life Deferred Policy Acquisition Costs by Product Life Deferred Policy Acquisition Costs by Product [Table Text Block] Life Deferred Policy Acquisition Costs by Product Investment Income, Realized Investment Gains And Losses And Change In Unrealized Investment Gains And Losses Schedule Of Investment Income Realized Gain Loss Comprehensive Income Loss Table [Table Text Block] Tabular disclosure of investment income derived from investments in debt and equity securities consisting of interest income earned from investments in debt securities and on cash and cash equivalents, dividend income from investments in equity securities, and income or expense derived from the amortization of investment related discounts or premiums; proceeds from sales of available-for-sale securities and the gross realized gains and gross realized losses that have been included in earnings as a result of those sales; components of comprehensive income. Change in life policy reserves, reinsurance recoverable and other, net of tax (benefit) of $(3), $0, $3 and $(3), respectively Change in life policy reserves, reinsurance recoverable and other, net of tax Change in life policy reserves, reinsurance recoverable and other, net of tax Share-based Compensation Arrangements by Share-based Payment Award, Award Type and Plan Name [Domain] Award Type [Domain] Additional Liability, Long-Duration Insurance [Roll Forward] Additional Liability, Long-Duration Insurance [Roll Forward] Non-PEO NEO Average Compensation Actually Paid Amount Non-PEO NEO Average Compensation Actually Paid Amount Balance, beginning of period Balance, end of period Liability for Future Policy Benefit, Expected Net Premium, before Reinsurance, after Discount Rate Change AOCI on Life Policy Reserves, Reinsurance Recoverable And Other Accumulated Net Unrealized Gain (Loss) on Life Policy Reserves, Reinsurance Recoverable And Other [Member] Accumulated Net Unrealized Gain (Loss) on Life Policy Reserves, Reinsurance Recoverable And Other Fair Value Measurements Fair Value Disclosures [Text Block] Level 3 Fair Value, Inputs, Level 3 [Member] United States government US Government Agencies Debt Securities [Member] Liability for Future Policy Benefit, Activity Liability for Future Policy Benefit, Activity [Table Text Block] Supplemental Disclosures of Cash Flow Information: Supplemental Cash Flow Information [Abstract] Cash surrender value Separate Account, Liability, Cash Surrender Value, Amount Shares acquired - share repurchase authorization (in shares) Treasury Stock, Shares, Acquired PEO Name PEO Name Total paid Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid Interest accrual Liability for Future Policy Benefit, Expected Net Premium, Interest Income Other assets Other Assets Stock Price or TSR Estimation Method Stock Price or TSR Estimation Method [Text Block] Entity Tax Identification Number Entity Tax Identification Number Reductions in the allowance for credit losses for securities sold Debt Securities, Available-for-Sale, Allowance for Credit Loss, Period Increase (Decrease) Policyholder Account Balance, Guaranteed Minimum Crediting Rate Range [Axis] Policyholder Account Balance, Guaranteed Minimum Crediting Rate Range [Axis] Note payable Notes Payable Shares acquired - share repurchase authorization Treasury Stock, Value, Acquired, Cost Method Cash and cash equivalents at beginning of year Cash and cash equivalents at end of period Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Continuing Operation Direct incurred loss and loss expenses Direct contract holders' benefits incurred Policyholder Benefits and Claims Incurred, Direct Benefit payments Policyholder Account Balance, Benefit Payment Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Aggregate Erroneous Compensation Not Yet Determined Aggregate Erroneous Compensation Not Yet Determined [Text Block] Material Terms of Trading Arrangement Material Terms of Trading Arrangement [Text Block] Non-NEOs Non-NEOs [Member] Separate Account, Liability [Table] Separate Account, Liability [Table] Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year [Member] Debt Instrument [Axis] Debt Instrument [Axis] Senior Notes 6.125% Due 2034 Senior Notes Six Point One Two Five Percent Due Twenty Thirty Four [Member] Senior Notes 6.125 Percent Due 2034 [Member] Shares acquired - share-based compensation plans, shares Shares acquired during period, Employee Share-Based Compensation Plans, Shares Shares acquired during period, Employee Share-Based Compensation Plans, Shares Interest credited Policyholder Account Balance, Interest Expense Cash surrender value Policyholder Account Balance, Cash Surrender Value 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 Net income — basic Basic (in USD per share) Earnings Per Share, Basic Change in allowance for credit losses, net Changes in Allowance for Credit Losses During Period Changes in Allowance for Credit Losses During Period Shares acquired - share repurchase authorization Payments for Repurchase of Common Stock Insider Trading Arrangements [Line Items] Award Type [Axis] Award Type [Axis] Change In Accumulated Other Comprehensive Income (AOCI) Change In Accumulated Other Comprehensive Income [Roll Forward] Change In Accumulated Other Comprehensive Income [Roll Forward] Effect of actual variances from expected experience Liability for Future Policy Benefit, Expected Future Policy Benefit, Cumulative Increase (Decrease) of Actual Variance from Expected Experience Present value of expected net premiums: Liability for Future Policy Benefit, Expected Net Premium [Roll Forward] Named Executive Officers, Footnote Named Executive Officers, Footnote [Text Block] Retained earnings Retained Earnings (Accumulated Deficit) Product and Service [Axis] Insurance Policy [Axis] Product and Service [Axis] Amortized deferred policy acquisition costs Deferred Policy Acquisition Costs, Amortization Expense Equity securities, at fair value (cost: 2026—$4,287; 2025—$4,155) Equity Securities, FV-NI Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table [Member] Excess and Surplus Lines Insurance Excess and Surplus Lines Insurance Excess and Surplus Lines Insurance [Member] Excess and Surplus Lines Insurance [Member] Change in unrealized gains, net, on investments available for sale, tax Other Comprehensive Income (Loss), Available-for-sale Securities and Other Assets Adjustment, Tax Other Comprehensive Income (Loss), Available-for-sale Securities and Other Assets Adjustment, Tax Less effect of discount rate assumption changes on reinsurance recoverable Effect of discount rate assumption changes on reinsurance recoverable Effect of discount rate assumption changes on reinsurance recoverable Awards Close in Time to MNPI Disclosures Awards Close in Time to MNPI Disclosures [Table] Qualified Pension Plans Pension Plan [Member] Common equities Common Stock [Member] Fixed maturities, at fair value (amortized cost: 2026—$19,280; 2025—$18,304) Fixed maturities, at fair value Debt Securities, Available-for-Sale Reclassification Out of Accumulated Other Comprehensive Income [Table] Reclassification out of Accumulated Other Comprehensive Income [Table] Compensation Actually Paid vs. Company Selected Measure Compensation Actually Paid vs. Company Selected Measure [Text Block] Cover [Abstract] Cover [Abstract] Change in unrealized gains, net, on investments available for sale, net of tax Other Comprehensive Income (Loss), Available-for-sale Securities and Other Assets Adjustment, Net of Tax Other Comprehensive Income (Loss), Available-for-sale Securities and Other Assets Adjustment, Net of Tax Effect of changes in cash flow assumptions Liability for Future Policy Benefit, Expected Future Policy Benefit, Cumulative Increase (Decrease) from Cash Flow Change Derivative, Name [Domain] Derivative Contract [Domain] Equity Awards Adjustments Equity Awards Adjustments [Member] Increase (decrease) resulting from: Effective Income Tax Rate Reconciliation, Other Reconciling Items, Amount [Abstract] Assumed earned premiums Assumed Premiums Earned Total liabilities and shareholders' equity Liabilities and Equity Deferred Policy Acquisition Costs Deferred Policy Acquisition Costs [Text Block] Interest accrual Additional Liability, Long-Duration Insurance, Interest Income (Expense) Investment gains and losses on securities sold, net Realized Investment Gains (Losses) Stock Options Share-Based Payment Arrangement, Option [Member] Reclassification adjustment, before tax Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax Property and Casualty Insurance Consolidated Property and Casualty Insurance Property, Liability and Casualty Insurance Product Line [Member] Category Industry Sector [Domain] Segments [Axis] Segments [Axis] Property Casualty Insurance Assumed And Ceded Business Property Casualty Insurance Assumed And Ceded Business [Table Text Block] Property Casualty Insurance Assumed And Ceded Business [Text Block] Other liabilities Increase (Decrease) in Other Operating Liabilities Additional 402(v) Disclosure Additional 402(v) Disclosure [Text Block] Geographic Distribution [Domain] Geographic Distribution [Domain] Tabular List, Table Tabular List [Table Text Block] Less reinsurance recoverable Plus reinsurance recoverable Reinsurance Recoverable for Unpaid Claims and Claims Adjustments Commercial Casualty Line Commercial Casualty Segment [Member] Commercial Casualty Segment [Member] Property Casualty Loss And Loss Expenses Liability for Future Policy Benefits and Unpaid Claims Disclosure [Text Block] Short-term Investments, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss Short-term Investments, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss Amount of accumulated unrealized loss on short-term investment measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset. Tax-exempt income from municipal bonds, Percent Effective Income Tax Rate Reconciliation, Tax Exempt Income, Percent Share-based compensation Purchase Of Treasury Shares Non Cash Purchase Of Treasury Shares Non Cash Issuances Liability for Future Policy Benefit, Expected Future Policy Benefit, Issuance Name Awards Close in Time to MNPI Disclosures, Individual Name Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested [Member] Ceded written premiums Ceded Premiums Written Weighted-average duration of the other additional liability in years Additional Liability, Long-Duration Insurance, Weighted-Average Duration Amortized Cost, Gross Unrealized Gains, Gross Unrealized Losses and Fair Value of Fixed-maturity Securities Debt Securities, Trading, and Equity Securities, FV-NI [Table Text Block] Separate Account, Liability [Roll Forward] Separate Account, Liability [Roll Forward] Premiums and reinsurance receivable Increase (Decrease ) in Premiums and Reinsurance receivable Increase (Decrease ) in Premiums and Reinsurance receivable Schedule of Defined Benefit Plans Disclosures Schedule of Defined Benefit Plans Disclosures [Table Text Block] Cincinnati Global MSP Underwriting Limited [Member] MSP Underwriting Limited [Member] Adjustment to Compensation: Adjustment to Compensation [Axis] Asset-backed Commercial Mortgage-Backed Securities [Member] Reclassification adjustment, net of tax Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax Adjusted beginning of period balance Additional Liability, Long-Duration Insurance, Original Discount Rate, before Reinsurance, after Cash Flow Change Investments, Available-for-Sale, Unrealized Loss Position Investments, Available-for-Sale, Unrealized Loss Position Amount of investment in available for sale security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position without allowance for credit loss. Senior Debentures 6.900 % Due 2028 Senior Debentures 6.9 Percent Due 2028 [Member] Senior Debentures 6.9 Percent Due 2028 [Member] Rule 10b5-1 Arrangement Terminated Rule 10b5-1 Arrangement Terminated [Flag] Aggregate Erroneous Compensation Amount Aggregate Erroneous Compensation Amount AOCI, Net of Tax Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract] Interest paid Interest Paid, Excluding Capitalized Interest, Operating Activity Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Policyholder Account Balance, Guaranteed Minimum Crediting Rate, Range from 0400 and Greater Policyholder Account Balance, Guaranteed Minimum Crediting Rate, Range from 0400 and Greater [Member] Attributed assessments Additional Liability, Long-Duration Insurance, Net Premium Collected Aggregate Available Trading Arrangement, Securities Aggregate Available Amount Long-term debt and lease obligations Long-Term Debt and Lease Obligation Name Measure Name Income Taxes Income Tax Disclosure [Text Block] Interest accretion Liability for Future Policy Benefit, Interest Expense Pay vs Performance Disclosure [Line Items] Adjusted beginning of period balance Ending balance at original discount rate Liability for Future Policy Benefit, Expected Net Premium, Original Discount Rate, before Reinsurance, after Cash Flow Change Fair Value, Measurements, Fair Value Hierarchy [Domain] Fair Value Hierarchy and NAV [Domain] Debt Instrument [Line Items] Debt Instrument [Line Items] Sale of equity securities Proceeds from Sale of Equity Securities, FV-NI Pay vs Performance Disclosure Pay vs Performance Disclosure [Table] Present value of expected future policy benefits: Liability for Future Policy Benefit, Expected Future Policy Benefit [Roll Forward] Loss and loss expense reserves Increase (Decrease) in Liability for Claims and Claims Adjustment Expense Reserve Retirement Plan Type [Domain] Retirement Plan Type [Domain] Reserve For Losses Loss Adjustment Expenses Table Schedule of Liability for Future Policy Benefits, by Product Segment [Table Text Block] Paid-In Capital Additional Paid-in Capital [Member] Entity Filer Category Entity Filer Category Total Fair Value Debt Securities, Available-for-Sale, Unrealized Loss Position Short-term investments, at fair value (amortized cost: 2026—$143; 2025—$148) Short-Term Investments Short-Term Investments Short-Term Investments Present value of expected future policy benefits less expected net premiums Liability for Future Policy Benefit, before Impact of Flooring at Cohort Level, Before Reinsurance Liability for Future Policy Benefit, before Impact of Flooring at Cohort Level, Before Reinsurance AOCI, tax, beginning of period AOCI, tax, end of period Accumulated Other Comprehensive Income Loss Tax Accumulated Other Comprehensive Income (Loss), Tax Name Trading Arrangement, Individual Name Cash and cash equivalents Cash and Cash Equivalent Effect of actual variances from expected experience Liability for Future Policy Benefit, Expected Net Premium, Cumulative Increase (Decrease) of Actual Variance from Expected Experience Number of Industries Operating In Number of Industries Operating In Number of Industries Operating In Contract holders' funds deposited Additions to Contract Holders Funds Interest credited before policy charges Separated Account, Liability, Increase (Decrease) from Interest Credited before Policy Charges Separated Account, Liability, Increase (Decrease) from Interest Credited before Policy Charges Company Selected Measure Amount Company Selected Measure Amount Investments, Available-for-Sale, Accumulated Gross Unrealized Gain Before Tax Investments, Available-for-Sale, Accumulated Gross Unrealized Gain Before Tax Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). Investment income: Net Investment Income [Abstract] Additional Liability, Long-Duration Insurance [Abstract] Total Gross Investment Income, Operating Change in life policy reserves, reinsurance recoverable and other, tax Change in life policy reserves, reinsurance recoverable and other, tax Change in life policy reserves, reinsurance recoverable and other, tax Impact of flooring at cohort level Liability for Future Policy Benefit, Impact of flooring at Cohort Level Liability for Future Policy Benefit, Impact of flooring at Cohort Level Non-PEO NEO Non-PEO NEO [Member] Entity Address, Address Line One Entity Address, Address Line One Total benefits and expenses Total Expenses Benefits, Losses and Expenses Total provision for income taxes Income Tax Expense (Benefit) Life Insurance Segment Life Insurance [Member] Life Insurance Award Timing Method Award Timing Method [Text Block] Balance, beginning of period Balance, end of period Discounted expected future benefit payments Liability for Future Policy Benefit, Expected Future Policy Benefit, before Reinsurance, after Discount Rate Change Personal Insurance Personal Lines Insurance [Member] Personal Lines Insurance Forgone Recovery, Explanation of Impracticability Forgone Recovery, Explanation of Impracticability [Text Block] Numerator: Net Income (Loss) Attributable to Parent [Abstract] Premiums receivable Premiums Receivable, Net Policyholder Account Balance, above Guaranteed Minimum Crediting Rate, Range from 0151 and Greater Policyholder Account Balance, above Guaranteed Minimum Crediting Rate, Range from 0151 and Greater [Member] Shadow reserve adjustments Additional Liability, Long-Duration Insurance, Shadow reserve adjustments Additional Liability, Long-Duration Insurance, Shadow reserve adjustments Other Investment Income Other Long-Term Investments Income derived from those other than interest and dividends. Amortization of actuarial gain and prior service cost Defined Benefit Plan, Amortization of Gain (Loss) Net Income Net Income Net income—basic and diluted Net Income (Loss) Attributable to Parent Erroneous Compensation Analysis Erroneous Compensation Analysis [Text Block] Statement Statement [Table] Restatement Determination Date: Restatement Determination Date [Axis] Proceeds from stock options exercised Proceeds from Stock Options Exercised Schedule of Accumulated Other Comprehensive Income (Loss) Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Interest Investment Interest Credited to Contract Holders Investment Income, Interest Property Casualty Insurance Assumed And Ceded Business Property Casualty Insurance Premiums Written On Assumed And Ceded Business [Line Items] [Line Items] for Property Casualty Insurance Premiums Written On Assumed And Ceded Business Geographic Distribution [Axis] Geographic Distribution [Axis] Discounted expected future gross premiums Liability for Future Policy Benefit, Expected Future Gross Premium, Discounted, before Reinsurance Reinsurance Disclosures [Abstract] Reinsurance Disclosures [Abstract] Policyholder Account Balance [Roll Forward] Policyholder Account Balance [Roll Forward] Revenues Revenues [Abstract] Pension Benefits Adjustments, Footnote Pension Benefits Adjustments, Footnote [Text Block]