| Current Federal Tax Expense (Benefit) | 211.00M | 2025-01-01 → 2025-12-31 |
| SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information, Deferred Policy Acquisition Cost | 1.72B | as of 2025-12-31 |
| SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information, Liability for Future Policy Benefit, Loss, Claim and Loss Expense | 33.55B | as of 2025-12-31 |
| SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information, Unearned Premium | 10.10B | as of 2025-12-31 |
| Current Income Tax Expense (Benefit) | 586.00M | 2025-01-01 → 2025-12-31 |
| SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information, Premium Revenue | 17.07B | 2025-01-01 → 2025-12-31 |
| SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information, Benefit, Claim, Loss and Settlement Expenses | 9.37B | 2025-01-01 → 2025-12-31 |
| Deferred Federal Income Tax Expense (Benefit) | 100.00M | 2025-01-01 → 2025-12-31 |
| SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information, Amortization of Deferred Policy Acquisition Cost | 3.15B | 2025-01-01 → 2025-12-31 |
| SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information, Other Operating Expense | 1.83B | 2025-01-01 → 2025-12-31 |
| SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information, Premium Written | 16.48B | 2025-01-01 → 2025-12-31 |
| Share-based Payment Arrangement, Expense | 148.00M | 2025-01-01 → 2025-12-31 |
| Indefinite-lived Intangible Assets, Foreign Currency Translation Gain (Loss) | 2.00M | 2025-01-01 → 2025-12-31 |
| Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount | 774.00M | 2025-01-01 → 2025-12-31 |
| Share-based Payment Arrangement, Expense, after Tax | 122.00M | 2025-01-01 → 2025-12-31 |
| Direct Premiums Earned | 10.20B | 2025-01-01 → 2025-12-31 |
| Ceded Premiums Earned | 6.22B | 2025-01-01 → 2025-12-31 |
| Assumed Premiums Earned | 13.09B | 2025-01-01 → 2025-12-31 |
| Derivative, Gain (Loss) on Derivative, Net | 327.00M | 2025-01-01 → 2025-12-31 |
| Equity Securities, FV-NI, Unrealized Gain (Loss) | 130.00M | 2025-01-01 → 2025-12-31 |
| Effective Income Tax Rate Reconciliation, Nondeductible Expense, Other, Amount | -22.00M | 2025-01-01 → 2025-12-31 |
| Dividends, Common Stock, Cash | 1.90B | 2025-01-01 → 2025-12-31 |
| Finite Lived Intangible Assets, Foreign Currency Translation Gain (Loss) | 24.00M | 2025-01-01 → 2025-12-31 |
| Effective Income Tax Rate Reconciliation, Tax Exempt Income, Amount | 54.00M | 2025-01-01 → 2025-12-31 |
| Debt Securities, Available-for-sale, Realized Gain | 296.00M | 2025-01-01 → 2025-12-31 |
| Debt Securities, Available-for-sale, Realized Loss | 271.00M | 2025-01-01 → 2025-12-31 |
| Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount | -65.00M | 2025-01-01 → 2025-12-31 |
| Effective Income Tax Rate Reconciliation, Other Reconciling Items, Amount | 20.00M | 2025-01-01 → 2025-12-31 |
| Finite-Lived Intangible Asset, Expected Amortization, Year One | 119.00M | as of 2025-12-31 |
| Finite-Lived Intangible Asset, Expected Amortization, Year Two | 93.00M | as of 2025-12-31 |
| Finite-Lived Intangible Asset, Expected Amortization, Year Three | 78.00M | as of 2025-12-31 |
| Finite-Lived Intangible Asset, Expected Amortization, Year Four | 65.00M | as of 2025-12-31 |
| Finite-Lived Intangible Asset, Expected Amortization, Year Five | 51.00M | as of 2025-12-31 |
| Finite-Lived Intangible Asset, Expected Amortization, after Year Five | 128.00M | as of 2025-12-31 |
| Net Income (Loss) Available to Common Stockholders, Diluted | 4.36B | 2025-01-01 → 2025-12-31 |
| Reinsurance Recoverable for Unpaid Claims and Claims Adjustments | 9.05B | as of 2025-12-31 |
| Reinsurance Recoverable for Paid and Unpaid Claims and Claims Adjustments | 9.53B | as of 2025-12-31 |
| Intangible Assets, Net (Including Goodwill) | 1.22B | as of 2025-12-31 |
| Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 121.00M | as of 2025-12-31 |
| Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | 169.00M | as of 2025-12-31 |
| Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss | 290.00M | as of 2025-12-31 |
| Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax | 408.00M | as of 2025-12-31 |
| Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | 290.00M | as of 2025-12-31 |
| Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months | 10.13B | as of 2025-12-31 |
| Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer | 2.77B | as of 2025-12-31 |
| Debt Securities, Available-for-sale, Unrealized Loss Position | 12.89B | as of 2025-12-31 |
| Deferred Tax Assets, Operating Loss Carryforwards | 72.00M | as of 2025-12-31 |
| Goodwill, Acquired During Period | 30.00M | 2025-01-01 → 2025-12-31 |
| Deferred Tax Assets, Tax Credit Carryforwards, Foreign | 54.00M | as of 2025-12-31 |
| Goodwill, Foreign Currency Translation Gain (Loss) | 6.00M | 2025-01-01 → 2025-12-31 |
| Operating Lease, Cost | 32.00M | 2025-01-01 → 2025-12-31 |
| Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits | 99.00M | as of 2025-12-31 |
| Lease, Cost | 36.00M | 2025-01-01 → 2025-12-31 |
| Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Unearned Premiums Reserve | 243.00M | as of 2025-12-31 |
| Right-of-Use Asset Obtained in Exchange for Operating Lease Liability | 13.00M | 2025-01-01 → 2025-12-31 |
| Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Loss Reserves | 116.00M | as of 2025-12-31 |
| Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Reserves | 18.00M | as of 2025-12-31 |
| Deferred Tax Assets, Tax Deferred Expense, Other | 10.00M | as of 2025-12-31 |
| Deferred Tax Assets, Goodwill and Intangible Assets | 835.00M | as of 2025-12-31 |
| Deferred Tax Assets, Unrealized Losses on Available-for-Sale Securities, Gross | 41.00M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid, Year One | 33.00M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid, Year Two | 31.00M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid, Year Three | 27.00M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid, Year Four | 21.00M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid, Year Five | 19.00M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid, after Year Five | 56.00M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid | 187.00M | as of 2025-12-31 |
| Purchase Commitment, Remaining Minimum Amount Committed | 307.00M | as of 2025-12-31 |
| Deferred Tax Assets, Gross | 1.76B | as of 2025-12-31 |
| Deferred Tax Assets, Valuation Allowance | 46.00M | as of 2025-12-31 |
| Deferred Tax Assets, Net of Valuation Allowance | 1.72B | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, Undiscounted Excess Amount | 31.00M | as of 2025-12-31 |
| Deferred Tax Liabilities, Gross | 300.00M | as of 2025-12-31 |
| Deferred Tax Assets, Net | 1.42B | as of 2025-12-31 |
| Deferred Tax Liabilities, Leasing Arrangements | 23.00M | as of 2025-12-31 |
| Deferred Tax Liabilities, Deferred Expense, Other Capitalized Costs | 77.00M | as of 2025-12-31 |
| Deferred Tax Liabilities, Other | 0 | as of 2025-12-31 |
| Reinsurance Recoverable, Allowance for Credit Loss, Period Increase (Decrease) | 0 | 2025-01-01 → 2025-12-31 |
| Finite-lived Intangible Assets Acquired | 2.00M | 2025-01-01 → 2025-12-31 |
| Premium Receivable, Allowance for Credit Loss, Writeoff | 3.00M | 2025-01-01 → 2025-12-31 |
| Premium Receivable, Allowance for Credit Loss, Period Increase (Decrease) | -2.00M | 2025-01-01 → 2025-12-31 |
| Indefinite-lived Intangible Assets Acquired | 0 | 2025-01-01 → 2025-12-31 |
| Liability for Unpaid Claims and Claims Adjustment Expense, Business Acquisitions | 50.00M | 2025-01-01 → 2025-12-31 |
| Liability for Unpaid Claims and Claims Adjustment Expense, Foreign Currency Translation Gain (Loss) | -550.00M | 2025-01-01 → 2025-12-31 |
| Defined Contribution Plan, Cost | 94.00M | 2025-01-01 → 2025-12-31 |
| Current Year Claims and Claims Adjustment Expense | 9.97B | 2025-01-01 → 2025-12-31 |
| Prior Year Claims and Claims Adjustment Expense | -600.00M | 2025-01-01 → 2025-12-31 |
| Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims | 9.37B | 2025-01-01 → 2025-12-31 |
| Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid, Current Year | 1.86B | 2025-01-01 → 2025-12-31 |
| Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid, Prior Years | 5.16B | 2025-01-01 → 2025-12-31 |
| Debt Securities, Available-for-sale, Allowance for Credit Loss | 20.00M | as of 2025-12-31 |
| Debt Securities, Available-for-sale, Allowance for Credit Loss, Period Increase (Decrease) | 6.00M | 2025-01-01 → 2025-12-31 |
| Unrecognized Tax Benefits | 6.00M | as of 2025-12-31 |
| Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions | 0 | 2025-01-01 → 2025-12-31 |
| Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions | 0 | 2025-01-01 → 2025-12-31 |
| Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions | 1.00M | 2025-01-01 → 2025-12-31 |
| Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount | 6.45B | as of 2025-12-31 |
| Income (Loss) from Continuing Operations before Income Taxes, Domestic | 3.12B | 2025-01-01 → 2025-12-31 |
| Advances from Federal Home Loan Banks | 0 | as of 2025-12-31 |
| Short-duration Insurance Contract, Discounted Liability, Discount | 78.00M | as of 2025-12-31 |
| Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net | 23.91B | as of 2025-12-31 |
| Short-duration Insurance Contracts, Liability for Unpaid Claims and Claims Adjustment Expense, Accumulated Unallocated Claim Adjustment Expense | 529.00M | as of 2025-12-31 |
| Short-duration Insurance Contracts, Liability for Unpaid Claims and Claim Adjustment Expense, Other Reconciling Item | 136.00M | as of 2025-12-31 |
| Short-duration Insurance Contracts, Liability for Unpaid Claims and Claim Adjustment Expense, Aggregate Reconciling Items | 587.00M | as of 2025-12-31 |
| Debt Securities, Available-for-sale, Amortized Cost | 34.95B | as of 2025-12-31 |
| Derivative Liability, Fair Value, Gross Liability | 72.00M | as of 2025-12-31 |
| Derivative Asset, Fair Value, Gross Asset | 180.00M | as of 2025-12-31 |