| Current Federal Tax Expense (Benefit) | 196.99M | 2025-01-01 → 2025-12-31 |
| Current State and Local Tax Expense (Benefit) | 219.00K | 2025-01-01 → 2025-12-31 |
| Deferred Federal Income Tax Expense (Benefit) | 77.53M | 2025-01-01 → 2025-12-31 |
| SEC Schedule, 12-04, Cash Dividends Paid to Registrant, Consolidated Subsidiaries | 816.00M | 2025-01-01 → 2025-12-31 |
| Federal Income Tax Expense (Benefit), Continuing Operations | 274.52M | 2025-01-01 → 2025-12-31 |
| State and Local Income Tax Expense (Benefit), Continuing Operations | 219.00K | 2025-01-01 → 2025-12-31 |
| Share-based Payment Arrangement, Amount Capitalized | 0 | 2025-01-01 → 2025-12-31 |
| Share-based Payment Arrangement, Expense | 53.35M | 2025-01-01 → 2025-12-31 |
| SEC Schedule, 12-17, Insurance Companies, Reinsurance, Life Insurance in Force, Gross | 229.80B | as of 2025-12-31 |
| SEC Schedule, 12-17, Insurance Companies, Reinsurance, Life Insurance in Force, Net | 231.11B | as of 2025-12-31 |
| Income Tax Expense (Benefit), Intraperiod Tax Allocation | 343.39M | 2025-01-01 → 2025-12-31 |
| Debt Instrument, Fair Value Disclosure | 2.53B | as of 2025-12-31 |
| Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount | 301.56M | 2025-01-01 → 2025-12-31 |
| Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount | 173.00K | 2025-01-01 → 2025-12-31 |
| Share-based Payment Arrangement, Expense, Tax Benefit | 10.83M | 2025-01-01 → 2025-12-31 |
| Line of Credit Facility, Maximum Amount Outstanding During Period | 605.50M | 2025-01-01 → 2025-12-31 |
| Share-based Payment Arrangement, Exercise of Option, Tax Benefit | 8.10M | 2025-01-01 → 2025-12-31 |
| Long-term Debt, Fair Value | 2.23B | as of 2025-12-31 |
| Effective Income Tax Rate Reconciliation, Tax Credit, Research, Amount | 1.40M | 2025-01-01 → 2025-12-31 |
| Short-term Debt, Fair Value | 304.66M | as of 2025-12-31 |
| EffectiveIncomeTaxRateReconciliationTaxCreditEnergyRelatedAmount | 4.99M | 2025-01-01 → 2025-12-31 |
| Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount | 49.46M | as of 2025-12-31 |
| Direct Premiums Earned | 4.81B | 2025-01-01 → 2025-12-31 |
| Assumed Premiums Earned | 28.33M | 2025-01-01 → 2025-12-31 |
| Letters of Credit Outstanding, Amount | 115.00M | as of 2025-12-31 |
| Other Labor-related Expenses | 41.61M | 2025-01-01 → 2025-12-31 |
| Line of Credit Facility, Remaining Borrowing Capacity | 579.00M | as of 2025-12-31 |
| Dividends, Common Stock | 87.28M | 2025-01-01 → 2025-12-31 |
| Effective Income Tax Rate Reconciliation, Tax Exempt Income, Amount | 9.52M | 2025-01-01 → 2025-12-31 |
| Debt Securities, Available-for-sale, Realized Gain | 8.38M | 2025-01-01 → 2025-12-31 |
| Debt Securities, Available-for-sale, Realized Loss | 20.55M | 2025-01-01 → 2025-12-31 |
| Debt Securities, Available-for-sale, Realized Gain (Loss) | -30.45M | 2025-01-01 → 2025-12-31 |
| Effective Income Tax Rate Reconciliation, Tax Expense (Benefit), Share-based Payment Arrangement, Amount | 377.00K | 2025-01-01 → 2025-12-31 |
| Effective Income Tax Rate Reconciliation, Other Adjustments, Amount | 448.00K | 2025-01-01 → 2025-12-31 |
| Treasury Stock, Value, Acquired, Cost Method | 880.98M | 2025-01-01 → 2025-12-31 |
| Defined Benefit Plan, Service Cost | 24.97M | 2025-01-01 → 2025-12-31 |
| Treasury Stock, Retired, Cost Method, Amount | 0 | 2025-01-01 → 2025-12-31 |
| Defined Benefit Plan, Interest Cost | 36.08M | 2025-01-01 → 2025-12-31 |
| Defined Benefit Plan, Expected Return (Loss) on Plan Assets | 46.28M | 2025-01-01 → 2025-12-31 |
| Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, Year One | 122.15M | as of 2025-12-31 |
| Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, after Year One Through Five | 847.25M | as of 2025-12-31 |
| Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, after Year 5 Through 10 | 1.94B | as of 2025-12-31 |
| Defined Benefit Plan, Amortization of Gain (Loss) | -45.00K | 2025-01-01 → 2025-12-31 |
| Defined Benefit Plan, Amortization of Prior Service Cost (Credit) | 1.17M | 2025-01-01 → 2025-12-31 |
| Defined Benefit Plan, Net Periodic Benefit Cost (Credit) | 15.98M | 2025-01-01 → 2025-12-31 |
| Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 67.28M | as of 2025-12-31 |
| Defined Benefit Plan, Benefit Obligation | 676.79M | as of 2025-12-31 |
| Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | 1.57B | as of 2025-12-31 |
| Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss | 1.64B | as of 2025-12-31 |
| Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax | 409.98M | as of 2025-12-31 |
| Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | 1.64B | as of 2025-12-31 |
| Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months | 2.06B | as of 2025-12-31 |
| Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer | 8.44B | as of 2025-12-31 |
| Debt Securities, Available-for-sale, Unrealized Loss Position | 10.50B | as of 2025-12-31 |
| Deferred Tax Assets, Operating Loss Carryforwards | 15.05M | as of 2025-12-31 |
| Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value | 144.25M | as of 2025-12-31 |
| Financing Receivable, Allowance for Credit Loss, Writeoff | 2.28M | 2025-01-01 → 2025-12-31 |
| Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value | 73.97M | 2025-01-01 → 2025-12-31 |
| Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value | 129.79M | as of 2025-12-31 |
| Financing Receivable, Allowance for Credit Loss, Period Increase (Decrease) | -3.10M | 2025-01-01 → 2025-12-31 |
| Operating Lease, Cost | 3.49M | 2025-01-01 → 2025-12-31 |
| Fair Value, Option, Changes in Fair Value, Gain (Loss) | -10.07M | 2025-01-01 → 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid, Year One | 6.96M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid, Year Two | 7.14M | as of 2025-12-31 |
| Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax | 36.97M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid, Year Three | 6.53M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid, Year Four | 5.92M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid, Year Five | 5.45M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid, after Year Five | 33.37M | as of 2025-12-31 |
| Deferred Tax Assets, Gross | 475.21M | as of 2025-12-31 |
| Deferred Tax Assets, Valuation Allowance | 2.63M | as of 2025-12-31 |
| Deferred Tax Assets, Net of Valuation Allowance | 472.58M | as of 2025-12-31 |
| Deferred Tax Liabilities, Gross | 1.41B | as of 2025-12-31 |
| Long-term Debt, Gross | 2.33B | as of 2025-12-31 |
| DebtSecuritiesAvailableForSaleAndHeldToMaturityAmortizedCostBeforeAllowanceForCreditLoss | 18.82B | as of 2025-12-31 |
| Debt, Long-term and Short-term, Combined Amount | 2.63B | as of 2025-12-31 |
| Insurance Commissions and Fees | 11.70M | 2025-01-01 → 2025-12-31 |
| OCI, before Reclassifications, Net of Tax, Attributable to Parent | 246.45M | 2025-01-01 → 2025-12-31 |
| Reclassification from AOCI, Current Period, Net of Tax, Attributable to Parent | -11.82M | 2025-01-01 → 2025-12-31 |
| Deferred Tax Liabilities, Other | 75.84M | as of 2025-12-31 |
| Deferred Tax Liabilities, Net | 935.06M | as of 2025-12-31 |
| Defined Benefit Plan, Accumulated Benefit Obligation | 604.41M | as of 2025-12-31 |
| Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Accumulated Benefit Obligation | 531.74M | as of 2025-12-31 |
| Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Plan Assets | 684.28M | as of 2025-12-31 |
| Defined Benefit Plan, Pension Plan with Projected Benefit Obligation in Excess of Plan Assets, Projected Benefit Obligation | 597.70M | as of 2025-12-31 |
| Defined Benefit Plan, Pension Plan with Projected Benefit Obligation in Excess of Plan Assets, Plan Assets | 684.28M | as of 2025-12-31 |
| Long-Term Debt, Maturity, Year One | 306.00M | as of 2025-12-31 |
| Defined Contribution Plan, Cost | 6.87M | 2025-01-01 → 2025-12-31 |
| Long-Term Debt, Maturity, Year Two | 250.00M | as of 2025-12-31 |
| Long-Term Debt, Maturity, Year Three | 550.00M | as of 2025-12-31 |
| Long-Term Debt, Maturity, Year Four | 0 | as of 2025-12-31 |
| Long-Term Debt, Maturity, Year Five | 400.00M | as of 2025-12-31 |
| Long-Term Debt, Maturity, after Year Five | 1.15B | as of 2025-12-31 |
| Debt Securities, Available-for-sale, Allowance for Credit Loss | 3.30M | as of 2025-12-31 |
| Operating Loss Carryforwards | 71.70M | as of 2025-12-31 |
| DebtSecuritiesAvailableForSaleExcludingAccruedInterestAllowanceForCreditLossNotPreviouslyRecorded | 0 | 2025-01-01 → 2025-12-31 |
| DebtSecuritiesAvailableForSaleExcludingAccruedInterestAllowanceForCreditLossSellBeforeRecovery | 7.12M | 2025-01-01 → 2025-12-31 |
| DebtSecuritiesAvailableForSaleExcludingAccruedInterestAllowanceForCreditLossNotToSellBeforeRecoveryCreditLossPreviouslyRecordedExpenseReversal | 20.00K | 2025-01-01 → 2025-12-31 |
| Debt Issuance Costs, Net | 6.29M | as of 2025-12-31 |
| Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net | 30.55M | as of 2025-12-31 |
| Unrecognized Tax Benefits | 0 | as of 2025-12-31 |
| Liability for Future Policy Benefit, before Reinsurance | 19.17B | as of 2025-12-31 |
| Amount of Restricted Net Assets for Consolidated and Unconsolidated Subsidiaries | 1.40B | as of 2025-12-31 |
| Income (Loss) from Continuing Operations before Income Taxes, Domestic | 1.40B | 2025-01-01 → 2025-12-31 |
| Other Receivables | 768.59M | as of 2025-12-31 |
| Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss), OCI | 5.03M | 2025-01-01 → 2025-12-31 |
| Equity Restrictions | 5.60B | as of 2025-12-31 |
| Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments | 558.00M | as of 2025-12-31 |
| DebtSecuritiesAvailableForSaleAmortizedCostAfterAllowanceForCreditLoss | 18.82B | as of 2025-12-31 |
| Debt Securities, Available-for-sale, Amortized Cost | 18.82B | as of 2025-12-31 |
| Deferred Tax Liabilities, Deferred Expense, Deferred Policy Acquisition Cost | 961.91M | as of 2025-12-31 |
| Statutory Accounting Practices, Statutory Net Income Amount | 748.75M | 2025-01-01 → 2025-12-31 |
| Statutory Accounting Practices, Statutory Capital and Surplus, Balance | 1.61B | as of 2025-12-31 |
| Statutory Accounting Practices, Statutory Amount Available for Dividend Payments without Regulatory Approval | 211.00M | as of 2025-12-31 |
| APIC, Share-based Payment Arrangement, Increase for Cost Recognition | 53.35M | 2025-01-01 → 2025-12-31 |