| SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information, Deferred Policy Acquisition Cost | 10.19B | as of 2025-12-31 |
| SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information, Liability for Future Policy Benefit, Loss, Claim and Loss Expense | 55.70M | as of 2025-12-31 |
| Current Federal, State and Local, Tax Expense (Benefit) | 74.70M | 2025-01-01 → 2025-12-31 |
| SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information, Unearned Premium | 20.88B | as of 2025-12-31 |
| Current Foreign Tax Expense (Benefit) | 38.60M | 2025-01-01 → 2025-12-31 |
| SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information, Other Policy Claim and Benefit Payable | 2.10B | as of 2025-12-31 |
| Current Income Tax Expense (Benefit) | 113.30M | 2025-01-01 → 2025-12-31 |
| SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information, Premium Revenue | 10.48B | 2025-01-01 → 2025-12-31 |
| SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information, Net Investment Income | 527.30M | 2025-01-01 → 2025-12-31 |
| SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information, Benefit, Claim, Loss and Settlement Expenses | 2.93B | 2025-01-01 → 2025-12-31 |
| SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information, Amortization of Deferred Policy Acquisition Cost | 4.10B | 2025-01-01 → 2025-12-31 |
| SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information, Other Operating Expense | 4.59B | 2025-01-01 → 2025-12-31 |
| Deferred Federal, State and Local, Tax Expense (Benefit) | 112.10M | 2025-01-01 → 2025-12-31 |
| SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information, Premium Written | 3.60B | 2025-01-01 → 2025-12-31 |
| Deferred Foreign Income Tax Expense (Benefit) | -10.70M | 2025-01-01 → 2025-12-31 |
| SEC Schedule, 12-09, Valuation Allowances and Reserves, Amount | 46.00M | as of 2025-12-31 |
| SEC Schedule, 12-17, Insurance Companies, Reinsurance, Life Insurance in Force, Gross | 7.33B | as of 2025-12-31 |
| SEC Schedule, 12-17, Insurance Companies, Reinsurance, Life Insurance in Force, Ceded | 4.61B | as of 2025-12-31 |
| SEC Schedule, 12-09, Valuation Allowances and Reserves, Additions, Charge to Cost and Expense | 9.70M | 2025-01-01 → 2025-12-31 |
| SEC Schedule, 12-17, Insurance Companies, Reinsurance, Life Insurance in Force, Assumed | 0 | as of 2025-12-31 |
| SEC Schedule, 12-09, Valuation Allowances and Reserves, Additions, Charge to Other Account | 400.00K | 2025-01-01 → 2025-12-31 |
| SEC Schedule, 12-17, Insurance Companies, Reinsurance, Life Insurance in Force, Net | 2.72B | as of 2025-12-31 |
| SEC Schedule, 12-09, Valuation Allowances and Reserves, Deduction | 1.50M | 2025-01-01 → 2025-12-31 |
| SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties, Cost | 10.13B | as of 2025-12-31 |
| SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties, Amount | 10.06B | as of 2025-12-31 |
| Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount | 228.40M | 2025-01-01 → 2025-12-31 |
| Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount | 12.10M | 2025-01-01 → 2025-12-31 |
| Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Amount | 9.10M | 2025-01-01 → 2025-12-31 |
| Restructuring and Related Cost, Incurred Cost | 27.30M | 2025-01-01 → 2025-12-31 |
| EffectiveIncomeTaxRateReconciliationFdiiAmount | 15.50M | 2025-01-01 → 2025-12-31 |
| Accrued Sales Commission | 640.60M | as of 2025-12-31 |
| EffectiveIncomeTaxRateReconciliationTaxCreditEnergyRelatedAmount | 12.50M | 2025-01-01 → 2025-12-31 |
| Direct Premiums Earned | 19.39B | 2025-01-01 → 2025-12-31 |
| Effective Income Tax Rate Reconciliation, Tax Credit, Other, Amount | 7.10M | 2025-01-01 → 2025-12-31 |
| Assets Held-in-trust | 0 | as of 2025-12-31 |
| Ceded Premiums Earned | 9.32B | 2025-01-01 → 2025-12-31 |
| Assumed Premiums Earned | 408.20M | 2025-01-01 → 2025-12-31 |
| Letters of Credit Outstanding, Amount | 1.70M | as of 2025-12-31 |
| Equity Securities, FV-NI, Unrealized Gain (Loss) | 19.80M | 2025-01-01 → 2025-12-31 |
| Effective Income Tax Rate Reconciliation, Nondeductible Expense, Amount | 6.80M | 2025-01-01 → 2025-12-31 |
| Equity Securities, FV-NI, Gain (Loss) | 5.90M | 2025-01-01 → 2025-12-31 |
| Equity Securities without Readily Determinable Fair Value, Amount | 115.30M | as of 2025-12-31 |
| Amount Recognized in Income Due to Inflationary Accounting | -7.30M | 2025-01-01 → 2025-12-31 |
| Effective Income Tax Rate Reconciliation, Tax Contingency, Amount | 1.00M | 2025-01-01 → 2025-12-31 |
| Dividends, Common Stock | 168.40M | 2025-01-01 → 2025-12-31 |
| Undistributed Earnings (Loss) Allocated to Participating Securities, Diluted | 7.70M | 2025-01-01 → 2025-12-31 |
| Debt Securities, Available-for-sale, Realized Gain | 4.20M | 2025-01-01 → 2025-12-31 |
| Debt Securities, Available-for-sale, Realized Loss | 75.10M | 2025-01-01 → 2025-12-31 |
| Debt Securities, Available-for-sale, Realized Gain (Loss) | -70.90M | 2025-01-01 → 2025-12-31 |
| Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount | 0 | 2025-01-01 → 2025-12-31 |
| Effective Income Tax Rate Reconciliation, Other Adjustments, Amount | -7.60M | 2025-01-01 → 2025-12-31 |
| Finite-Lived Intangible Asset, Expected Amortization, Year One | 107.00M | as of 2025-12-31 |
| Finite-Lived Intangible Asset, Expected Amortization, Year Two | 86.40M | as of 2025-12-31 |
| Finite-Lived Intangible Asset, Expected Amortization, Year Three | 75.20M | as of 2025-12-31 |
| Finite-Lived Intangible Asset, Expected Amortization, Year Four | 60.80M | as of 2025-12-31 |
| Finite-Lived Intangible Asset, Expected Amortization, Year Five | 56.30M | as of 2025-12-31 |
| Finite-Lived Intangible Asset, Expected Amortization, after Year Five | 124.60M | as of 2025-12-31 |
| Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, Year One | 120.40M | as of 2025-12-31 |
| Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, after Year One Through Five | 1.38B | as of 2025-12-31 |
| Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, after Year 5 Through 10 | 3.55B | as of 2025-12-31 |
| Debt Securities, Available-for-Sale, Amortized Cost, Maturity, Allocated and Single Maturity Date, after Year 10 | 1.33B | as of 2025-12-31 |
| Intangible Assets, Gross (Excluding Goodwill) | 1.23B | as of 2025-12-31 |
| Net Income (Loss) Available to Common Stockholders, Diluted | 865.00M | 2025-01-01 → 2025-12-31 |
| Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, Year One | 120.60M | as of 2025-12-31 |
| Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, after Year One Through Five | 1.39B | as of 2025-12-31 |
| Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, after Year 5 Through 10 | 3.62B | as of 2025-12-31 |
| Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, after Year 10 | 1.22B | as of 2025-12-31 |
| Long-Lived Assets | 841.70M | as of 2025-12-31 |
| Stock Repurchase Program, Remaining Authorized Repurchase Amount | 774.60M | as of 2025-12-31 |
| Reinsurance Recoverable for Unpaid Claims and Claims Adjustments | 898.10M | as of 2025-12-31 |
| Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 18.10M | as of 2025-12-31 |
| Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | 212.50M | as of 2025-12-31 |
| Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss | 230.60M | as of 2025-12-31 |
| Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax | 174.90M | as of 2025-12-31 |
| Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | 230.60M | as of 2025-12-31 |
| Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months | 1.13B | as of 2025-12-31 |
| Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer | 1.40B | as of 2025-12-31 |
| Debt Securities, Available-for-sale, Unrealized Loss Position | 2.53B | as of 2025-12-31 |
| Deferred Tax Assets, Operating Loss Carryforwards | 36.20M | as of 2025-12-31 |
| Stock Repurchased During Period, Value | 299.90M | 2025-01-01 → 2025-12-31 |
| Deferred Tax Assets, Tax Credit Carryforwards | 13.10M | as of 2025-12-31 |
| Goodwill, Foreign Currency Translation Gain (Loss) | 12.00M | 2025-01-01 → 2025-12-31 |
| Deferred Tax Assets, Capital Loss Carryforwards | 26.70M | as of 2025-12-31 |
| Goodwill, Transfers | 0 | 2025-01-01 → 2025-12-31 |
| Funds Held under Reinsurance Agreements, Liability | 266.40M | as of 2025-12-31 |
| Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Postretirement Benefits | 7.00M | as of 2025-12-31 |
| Operating Lease, Cost | 19.00M | 2025-01-01 → 2025-12-31 |
| Goodwill, Impaired, Accumulated Impairment Loss | 1.41B | as of 2025-12-31 |
| Short-term Lease, Cost | 3.30M | 2025-01-01 → 2025-12-31 |
| Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits | 43.80M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid, Year One | 20.30M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid, Year Two | 16.70M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid, Year Three | 13.30M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid, Year Four | 11.70M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid, Year Five | 8.80M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid, after Year Five | 16.30M | as of 2025-12-31 |
| Deferred Tax Assets, Investments | 20.90M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid | 87.10M | as of 2025-12-31 |
| Deferred Tax Assets, Other | 113.20M | as of 2025-12-31 |
| Deferred Tax Assets, Gross | 856.70M | as of 2025-12-31 |
| Deferred Tax Assets, Valuation Allowance | 20.00M | as of 2025-12-31 |
| Deferred Tax Assets, Net of Valuation Allowance | 836.70M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, Undiscounted Excess Amount | 13.20M | as of 2025-12-31 |
| Deferred Tax Liabilities, Gross | 1.19B | as of 2025-12-31 |
| Deferred Policy Acquisition Cost, Capitalization | 4.29B | 2025-01-01 → 2025-12-31 |
| Present Value of Future Insurance Profits, Expected Amortization, Year One | 1.70M | as of 2025-12-31 |
| Present Value of Future Insurance Profits, Expected Amortization, Year Two | 1.40M | as of 2025-12-31 |
| Present Value of Future Insurance Profits, Expected Amortization, Year Three | 800.00K | as of 2025-12-31 |
| Present Value of Future Insurance Profits, Expected Amortization, Year Four | 400.00K | as of 2025-12-31 |
| Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year | 0 | as of 2025-12-31 |
| Marketable Securities, Gain (Loss), Excluding Other-than-temporary Impairment Loss | -71.80M | 2025-01-01 → 2025-12-31 |
| OCI, before Reclassifications, Net of Tax, Attributable to Parent | 233.20M | 2025-01-01 → 2025-12-31 |
| Deferred Tax Liabilities, Intangible Assets | 94.00M | as of 2025-12-31 |
| Reclassification from AOCI, Current Period, Net of Tax, Attributable to Parent | -58.70M | 2025-01-01 → 2025-12-31 |
| Present Value of Future Insurance Profits, Foreign Currency Translation Gain (Loss) | -100.00K | 2025-01-01 → 2025-12-31 |
| Deferred Tax Liabilities, Net | 351.50M | as of 2025-12-31 |
| Equity Securities without Readily Determinable Fair Value, Upward Price Adjustment, Cumulative Amount | 55.60M | as of 2025-12-31 |
| Equity Securities without Readily Determinable Fair Value, Impairment Loss, Annual Amount | 4.70M | 2025-01-01 → 2025-12-31 |
| Equity Securities without Readily Determinable Fair Value, Upward Price Adjustment, Annual Amount | 4.80M | 2025-01-01 → 2025-12-31 |
| Reinsurance Recoverable, Credit Loss Expense (Reversal) | 200.00K | 2025-01-01 → 2025-12-31 |
| Liability for Unpaid Claims and Claims Adjustment Expense, Reported Claims, Amount | 392.60M | as of 2025-12-31 |
| Liability for Unpaid Claims and Claims Adjustment Expense, Incurred but Not Reported (IBNR) Claims, Amount | 1.71B | as of 2025-12-31 |
| Defined Contribution Plan, Cost | 45.40M | 2025-01-01 → 2025-12-31 |
| Current Year Claims and Claims Adjustment Expense | 3.07B | 2025-01-01 → 2025-12-31 |
| Prior Year Claims and Claims Adjustment Expense | -142.80M | 2025-01-01 → 2025-12-31 |
| Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims | 2.93B | 2025-01-01 → 2025-12-31 |
| Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid, Current Year | 2.27B | 2025-01-01 → 2025-12-31 |
| Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid, Prior Years | 697.80M | 2025-01-01 → 2025-12-31 |
| Debt Securities, Available-for-sale, Allowance for Credit Loss | 1.90M | as of 2025-12-31 |
| Unrecognized Tax Benefits | 18.80M | as of 2025-12-31 |
| Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions | 900.00K | 2025-01-01 → 2025-12-31 |
| Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions | 600.00K | 2025-01-01 → 2025-12-31 |
| Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions | 1.20M | 2025-01-01 → 2025-12-31 |
| Unrecognized Tax Benefits, Interest on Income Taxes Expense | 600.00K | 2025-01-01 → 2025-12-31 |
| Unrecognized Tax Benefits, Income Tax Penalties Accrued | 200.00K | as of 2025-12-31 |
| Unrecognized Tax Benefits, Interest on Income Taxes Accrued | 4.60M | as of 2025-12-31 |
| Unrecognized Tax Benefits that Would Impact Effective Tax Rate | 22.80M | as of 2025-12-31 |
| Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount | 327.20M | as of 2025-12-31 |
| Liability for Future Policy Benefit, before Reinsurance | 55.70M | as of 2025-12-31 |
| Income (Loss) from Continuing Operations before Income Taxes, Domestic | 1.00B | 2025-01-01 → 2025-12-31 |
| Income (Loss) from Continuing Operations before Income Taxes, Foreign | 85.80M | 2025-01-01 → 2025-12-31 |
| Other Receivables | 77.10M | as of 2025-12-31 |
| Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net | 1.19B | as of 2025-12-31 |
| Short-duration Insurance Contracts, Liability for Unpaid Claims and Claims Adjustment Expense, Accumulated Unallocated Claim Adjustment Expense | 16.10M | as of 2025-12-31 |
| Debt Securities, Available-for-sale, Amortized Cost | 8.64B | as of 2025-12-31 |
| Deferred Tax Liabilities, Deferred Expense, Deferred Policy Acquisition Cost | 1.09B | as of 2025-12-31 |
| Statutory Accounting Practices, Statutory Net Income Amount | 755.80M | 2025-01-01 → 2025-12-31 |
| Statutory Accounting Practices, Statutory Capital and Surplus, Balance | 1.73B | as of 2025-12-31 |
| Statutory Accounting Practices, Statutory Amount Available for Dividend Payments without Regulatory Approval | 791.90M | as of 2025-12-31 |
| APIC, Share-based Payment Arrangement, Increase for Cost Recognition | 85.70M | 2025-01-01 → 2025-12-31 |