| Current Federal Tax Expense (Benefit) | 399.80M | 2025-01-01 → 2025-12-31 |
| SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information, Deferred Policy Acquisition Cost | 1.00B | as of 2025-12-31 |
| Current State and Local Tax Expense (Benefit) | 13.60M | 2025-01-01 → 2025-12-31 |
| SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information, Liability for Future Policy Benefit, Loss, Claim and Loss Expense | 22.21B | as of 2025-12-31 |
| SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information, Unearned Premium | 6.72B | as of 2025-12-31 |
| Current Foreign Tax Expense (Benefit) | 96.86M | 2025-01-01 → 2025-12-31 |
| Current Income Tax Expense (Benefit) | 510.25M | 2025-01-01 → 2025-12-31 |
| SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information, Premium Revenue | 12.45B | 2025-01-01 → 2025-12-31 |
| SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information, Net Investment Income | 1.43B | 2025-01-01 → 2025-12-31 |
| SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information, Benefit, Claim, Loss and Settlement Expenses | 7.77B | 2025-01-01 → 2025-12-31 |
| Deferred Federal Income Tax Expense (Benefit) | -16.71M | 2025-01-01 → 2025-12-31 |
| SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information, Amortization of Deferred Policy Acquisition Cost | 1.38B | 2025-01-01 → 2025-12-31 |
| SEC Schedule, 12-18, Supplemental Information, Property-Casualty Insurance Underwriters, Deferred Policy Acquisition Cost | 1.00B | as of 2025-12-31 |
| Deferred State and Local Income Tax Expense (Benefit) | -561.00K | 2025-01-01 → 2025-12-31 |
| SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information, Other Operating Expense | 2.59B | 2025-01-01 → 2025-12-31 |
| SEC Schedule, 12-18, Supplemental Information, Property-Casualty Insurance Underwriters, Reserve for Unpaid Claim and Claim Adjustment Expense | 22.21B | as of 2025-12-31 |
| SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation, Depreciation Expense | 9.45M | 2025-01-01 → 2025-12-31 |
| SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information, Premium Written | 12.71B | 2025-01-01 → 2025-12-31 |
| Deferred Foreign Income Tax Expense (Benefit) | 2.78M | 2025-01-01 → 2025-12-31 |
| SEC Schedule, 12-18, Supplemental Information, Property-Casualty Insurance Underwriters, Unearned Premium | 6.72B | as of 2025-12-31 |
| SEC Schedule, 12-18, Supplemental Information, Property-Casualty Insurance Underwriters, Earned Premium | 12.45B | 2025-01-01 → 2025-12-31 |
| Loans Receivable, Fair Value Disclosure | 419.07M | as of 2025-12-31 |
| SEC Schedule, 12-18, Supplemental Information, Property-Casualty Insurance Underwriters, Net Investment Income | 1.43B | 2025-01-01 → 2025-12-31 |
| SEC Schedule, 12-18, Supplemental Information, Property-Casualty Insurance Underwriters, Amortization of Deferred Policy Acquisition Cost | 1.38B | 2025-01-01 → 2025-12-31 |
| SEC Schedule, 12-18, Supplemental Information, Property-Casualty Insurance Underwriters, Paid Claim and Claim Adjustment Expense | 6.13B | 2025-01-01 → 2025-12-31 |
| SEC Schedule, 12-18, Supplemental Information, Property-Casualty Insurance Underwriters, Premium Written | 12.71B | 2025-01-01 → 2025-12-31 |
| SEC Schedule, 12-04, Cash Dividends Paid to Registrant, Subsidiaries and Equity Method Investees | 1.64B | 2025-01-01 → 2025-12-31 |
| Federal Income Tax Expense (Benefit), Continuing Operations | 383.09M | 2025-01-01 → 2025-12-31 |
| State and Local Income Tax Expense (Benefit), Continuing Operations | 13.04M | 2025-01-01 → 2025-12-31 |
| Foreign Income Tax Expense (Benefit), Continuing Operations | 99.64M | 2025-01-01 → 2025-12-31 |
| Deferred Compensation Arrangement with Individual, Compensation Expense | 23.20M | 2025-01-01 → 2025-12-31 |
| Debt Securities, Trading, and Equity Securities, FV-NI | 1.22B | as of 2025-12-31 |
| Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount | 478.91M | 2025-01-01 → 2025-12-31 |
| Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount | 10.30M | 2025-01-01 → 2025-12-31 |
| Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Amount | 11.63M | 2025-01-01 → 2025-12-31 |
| EffectiveIncomeTaxRateReconciliationCrossBorderTaxEffectAmount | -14.73M | 2025-01-01 → 2025-12-31 |
| Direct Premiums Earned | 13.40B | 2025-01-01 → 2025-12-31 |
| Ceded Premiums Earned | 2.34B | 2025-01-01 → 2025-12-31 |
| Assumed Premiums Earned | 1.39B | 2025-01-01 → 2025-12-31 |
| Equity Securities, FV-NI, Unrealized Gain (Loss) | 96.34M | 2025-01-01 → 2025-12-31 |
| Effective Income Tax Rate Reconciliation, Nondeductible Expense, Amount | -10.08M | 2025-01-01 → 2025-12-31 |
| SegmentReportingOtherItemAmount | 1.14B | 2025-01-01 → 2025-12-31 |
| Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount | 19.73M | 2025-01-01 → 2025-12-31 |
| Reinsurance Recoverable for Unpaid Claims and Claims Adjustments | 3.25B | as of 2025-12-31 |
| Reinsurance Recoverable for Paid and Unpaid Claims and Claims Adjustments | 3.54B | as of 2025-12-31 |
| Deferred Tax Assets, Operating Loss Carryforwards | 77.81M | as of 2025-12-31 |
| Financing Receivable, Allowance for Credit Loss, Period Increase (Decrease) | 953.00K | 2025-01-01 → 2025-12-31 |
| Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss | 0 | as of 2025-12-31 |
| Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain | 872.00K | as of 2025-12-31 |
| Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Share-based Compensation Cost | 83.03M | as of 2025-12-31 |
| Operating Lease, Cost | 54.26M | 2025-01-01 → 2025-12-31 |
| Compensation and Benefits Trust | 43.00M | as of 2025-12-31 |
| Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Unearned Premiums Reserve | 228.75M | as of 2025-12-31 |
| Right-of-Use Asset Obtained in Exchange for Operating Lease Liability | 74.45M | 2025-01-01 → 2025-12-31 |
| Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Loss Reserves | 253.98M | as of 2025-12-31 |
| Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Impairment Losses | 5.01M | as of 2025-12-31 |
| Deferred Tax Assets, Unrealized Losses on Trading Securities | 0 | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid, Year One | 54.48M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid, Year Two | 47.25M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid, Year Three | 45.83M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid, Year Four | 41.83M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid, Year Five | 37.01M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid, after Year Five | 96.20M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid | 322.58M | as of 2025-12-31 |
| Deferred Tax Assets, Other | 82.95M | as of 2025-12-31 |
| Deferred Tax Assets, Gross | 731.53M | as of 2025-12-31 |
| Deferred Tax Assets, Valuation Allowance | 55.79M | as of 2025-12-31 |
| Deferred Tax Assets, Net of Valuation Allowance | 675.74M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, Undiscounted Excess Amount | 62.13M | as of 2025-12-31 |
| Deferred Tax Liabilities, Gross | 634.12M | as of 2025-12-31 |
| Deferred Tax Assets, Net | 41.62M | as of 2025-12-31 |
| Debt Securities, Held-to-maturity, Restricted | 1.15B | as of 2025-12-31 |
| Debt Securities, Available-for-sale and Held-to-maturity | 25.05B | as of 2025-12-31 |
| DebtSecuritiesAvailableForSaleAndHeldToMaturityFairValue | 25.05B | as of 2025-12-31 |
| Deferred Tax Liabilities, Property, Plant and Equipment | 61.48M | as of 2025-12-31 |
| Insurance Commissions and Fees | 118.51M | 2025-01-01 → 2025-12-31 |
| Debt Securities, Held-to-maturity, Credit Loss Expense (Reversal) | -16.00K | 2025-01-01 → 2025-12-31 |
| Deferred Tax Liabilities, Investments | 229.69M | as of 2025-12-31 |
| Marketable Securities, Realized Gain (Loss), Excluding Other-than-temporary Impairment Loss | 130.67M | 2025-01-01 → 2025-12-31 |
| Deferred Tax Liabilities, Intangible Assets | 15.54M | as of 2025-12-31 |
| Deferred Tax Liabilities, Other | 80.78M | as of 2025-12-31 |
| Undistributed Earnings of Foreign Subsidiaries | 585.00M | as of 2025-12-31 |
| Reinsurance Recoverable, Credit Loss Expense (Reversal) | -1.97M | 2025-01-01 → 2025-12-31 |
| Premium Receivable, Credit Loss Expense (Reversal) | 2.12M | 2025-01-01 → 2025-12-31 |
| Current Year Claims and Claims Adjustment Expense | 7.70B | 2025-01-01 → 2025-12-31 |
| Prior Year Claims and Claims Adjustment Expense | 34.45M | 2025-01-01 → 2025-12-31 |
| Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims | 7.77B | 2025-01-01 → 2025-12-31 |
| Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid, Current Year | 1.38B | 2025-01-01 → 2025-12-31 |
| Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid, Prior Years | 4.76B | 2025-01-01 → 2025-12-31 |
| Debt Securities, Available-for-sale, Allowance for Credit Loss | 65.00K | as of 2025-12-31 |
| Debt Securities, Available-for-sale, Allowance for Credit Loss, Not Previously Recorded | 78.00K | 2025-01-01 → 2025-12-31 |
| Debt Securities, Available-for-sale, Allowance for Credit Loss, Securities Sold | 0 | 2025-01-01 → 2025-12-31 |
| Debt Securities, Available-for-sale, Allowance for Credit Loss, Not to Sell before Recovery, Credit Loss, Previously Recorded, Expense (Reversal) | -659.00K | 2025-01-01 → 2025-12-31 |
| Liability for Asbestos and Environmental Claims, Net | 13.00M | as of 2025-12-31 |
| Tax Credit Carryforward, Valuation Allowance | 56.00M | as of 2025-12-31 |
| Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount | 274.00M | as of 2025-12-31 |
| Lessor, Operating Lease, Payment to be Received, Year One | 36.77M | as of 2025-12-31 |
| Lessor, Operating Lease, Payment to be Received, Year Two | 39.90M | as of 2025-12-31 |
| Lessor, Operating Lease, Payment to be Received, Year Three | 42.51M | as of 2025-12-31 |
| Lessor, Operating Lease, Payment to be Received, Year Four | 37.19M | as of 2025-12-31 |
| Lessor, Operating Lease, Payment to be Received, Year Five | 31.56M | as of 2025-12-31 |
| Lessor, Operating Lease, Payment to be Received, after Year Five | 373.88M | as of 2025-12-31 |
| Income Taxes Receivable, Current | 2.73M | as of 2025-12-31 |
| Income (Loss) from Continuing Operations before Income Taxes, Domestic | 1.88B | 2025-01-01 → 2025-12-31 |
| Income (Loss) from Continuing Operations before Income Taxes, Foreign | 400.00M | 2025-01-01 → 2025-12-31 |
| Short-duration Insurance Contract, Discounted Liability, Discount | 420.40M | as of 2025-12-31 |
| Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net | 19.37B | as of 2025-12-31 |
| Debt Securities, Available-for-sale, Amortized Cost | 25.14B | as of 2025-12-31 |
| Workers' Compensation Discount, Prior Year Amount | 1.40B | as of 2025-12-31 |
| Deferred Tax Liabilities, Deferred Expense, Deferred Policy Acquisition Cost | 204.98M | as of 2025-12-31 |
| Statutory Accounting Practices, Statutory Net Income Amount | 1.59B | 2025-01-01 → 2025-12-31 |
| Statutory Accounting Practices, Statutory Capital and Surplus, Balance | 9.86B | as of 2025-12-31 |
| Statutory Accounting Practices, Statutory Amount Available for Dividend Payments without Regulatory Approval | 1.40B | as of 2025-12-31 |