| Current Federal Tax Expense (Benefit) | 3.04B | 2025-01-01 → 2025-12-31 |
| SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information, Deferred Policy Acquisition Cost | 2.04B | as of 2025-12-31 |
| Current State and Local Tax Expense (Benefit) | 75.00M | 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 | 43.31B | as of 2025-12-31 |
| Current Federal, State and Local, Tax Expense (Benefit) | 3.12B | 2025-01-01 → 2025-12-31 |
| SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information, Unearned Premium | 25.22B | as of 2025-12-31 |
| SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information, Other Policy Claim and Benefit Payable | 0 | as of 2025-12-31 |
| SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information, Premium Revenue | 81.66B | 2025-01-01 → 2025-12-31 |
| SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information, Net Investment Income | 3.55B | 2025-01-01 → 2025-12-31 |
| SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information, Benefit, Claim, Loss and Settlement Expenses | 53.96B | 2025-01-01 → 2025-12-31 |
| Deferred Federal Income Tax Expense (Benefit) | -199.00M | 2025-01-01 → 2025-12-31 |
| SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information, Amortization of Deferred Policy Acquisition Cost | 6.10B | 2025-01-01 → 2025-12-31 |
| Deferred State and Local Income Tax Expense (Benefit) | -3.00M | 2025-01-01 → 2025-12-31 |
| SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information, Other Operating Expense | 12.55B | 2025-01-01 → 2025-12-31 |
| Deferred Federal, State and Local, Tax Expense (Benefit) | -202.00M | 2025-01-01 → 2025-12-31 |
| SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information, Premium Written | 83.17B | 2025-01-01 → 2025-12-31 |
| Investments, Fair Value Disclosure | 97.37B | as of 2025-12-31 |
| Share-based Payment Arrangement, Expense | 132.00M | 2025-01-01 → 2025-12-31 |
| SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties, Cost | 93.95B | as of 2025-12-31 |
| SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties, Fair Value | 97.37B | as of 2025-12-31 |
| SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties, Amount | 97.37B | as of 2025-12-31 |
| Deposit Assets | 787.00M | as of 2025-12-31 |
| Deferred Compensation Plan Assets | 196.00M | as of 2025-12-31 |
| Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount | 2.99B | 2025-01-01 → 2025-12-31 |
| Equity Securities, FV-NI, Cost | 1.24B | as of 2025-12-31 |
| Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount | 57.00M | 2025-01-01 → 2025-12-31 |
| Share-based Payment Arrangement, Expense, Tax Benefit | 18.00M | 2025-01-01 → 2025-12-31 |
| Long-term Debt, Fair Value | 6.34B | as of 2025-12-31 |
| Effective Income Tax Rate Reconciliation, Tax Credit, Investment, Amount | 6.00M | 2025-01-01 → 2025-12-31 |
| Direct Premiums Earned | 82.85B | 2025-01-01 → 2025-12-31 |
| Ceded Premiums Earned | 1.19B | 2025-01-01 → 2025-12-31 |
| Debt and Equity Securities, Unrealized Gain (Loss) | 480.00M | 2025-01-01 → 2025-12-31 |
| Equity Securities, FV-NI, Unrealized Gain (Loss) | 462.00M | 2025-01-01 → 2025-12-31 |
| Equity Securities, FV-NI, Realized Gain | 107.00M | 2025-01-01 → 2025-12-31 |
| Equity Securities, FV-NI, Realized Loss | 16.00M | 2025-01-01 → 2025-12-31 |
| Effective Income Tax Rate Reconciliation, Nondeductible Expense, Amount | -123.00M | 2025-01-01 → 2025-12-31 |
| Equity Securities, FV-NI, Gain (Loss) | 553.00M | 2025-01-01 → 2025-12-31 |
| Debt Securities, Available-for-sale, Realized Gain | 327.00M | 2025-01-01 → 2025-12-31 |
| Debt Securities, Available-for-sale, Realized Loss | 170.00M | 2025-01-01 → 2025-12-31 |
| Debt Securities, Available-for-sale, Realized Gain (Loss) | 157.00M | 2025-01-01 → 2025-12-31 |
| Reinsurance Recoverable for Unpaid Claims and Claims Adjustments | 3.80B | as of 2025-12-31 |
| Reinsurance Recoverable for Paid and Unpaid Claims and Claims Adjustments | 4.08B | as of 2025-12-31 |
| Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 67.00M | as of 2025-12-31 |
| Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | 686.00M | as of 2025-12-31 |
| Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss | 753.00M | as of 2025-12-31 |
| Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax | 901.00M | as of 2025-12-31 |
| Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | 753.00M | as of 2025-12-31 |
| Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months | 15.41B | as of 2025-12-31 |
| Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer | 13.17B | as of 2025-12-31 |
| Debt Securities, Available-for-sale, Unrealized Loss Position | 28.58B | as of 2025-12-31 |
| Unrecorded Unconditional Purchase Obligation, to be Paid, Year One | 1.41B | as of 2025-12-31 |
| Unrecorded Unconditional Purchase Obligation, to be Paid, Year Two | 454.00M | as of 2025-12-31 |
| Unrecorded Unconditional Purchase Obligation, to be Paid, Year Three | 350.00M | as of 2025-12-31 |
| Unrecorded Unconditional Purchase Obligation, to be Paid, Year Four | 298.00M | as of 2025-12-31 |
| Unrecorded Unconditional Purchase Obligation, to be Paid, Year Five | 269.00M | as of 2025-12-31 |
| Unrecorded Unconditional Purchase Obligation, to be Paid, after Year Five | 221.00M | as of 2025-12-31 |
| Unrecorded Unconditional Purchase Obligation | 3.00B | as of 2025-12-31 |
| Lease, Cost | 110.00M | 2025-01-01 → 2025-12-31 |
| Right-of-Use Asset Obtained in Exchange for Operating Lease Liability | 91.00M | 2025-01-01 → 2025-12-31 |
| Deferred Tax Assets, State Taxes | 38.00M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid, Year One | 90.00M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid, Year Two | 55.00M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid, Year Three | 36.00M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid, Year Four | 23.00M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid, Year Five | 12.00M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid, after Year Five | 6.00M | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, to be Paid | 222.00M | as of 2025-12-31 |
| Deferred Tax Assets, Valuation Allowance | 0 | as of 2025-12-31 |
| Lessee, Operating Lease, Liability, Undiscounted Excess Amount | 17.00M | as of 2025-12-31 |
| Deferred Tax Assets, Net | 785.00M | as of 2025-12-31 |
| Long-term Debt, Gross | 6.95B | as of 2025-12-31 |
| Debt, Long-term and Short-term, Combined Amount | 6.90B | as of 2025-12-31 |
| Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax | 131.00M | 2025-01-01 → 2025-12-31 |
| Debt and Equity Securities, Gain (Loss) | 727.00M | 2025-01-01 → 2025-12-31 |
| Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax | 153.00M | 2025-01-01 → 2025-12-31 |
| AOCI before Tax, Attributable to Parent | 130.00M | as of 2025-12-31 |
| AOCI Tax, Attributable to Parent | 27.00M | as of 2025-12-31 |
| Premium Receivable, Allowance for Credit Loss, Writeoff | 669.00M | 2025-01-01 → 2025-12-31 |
| Premium Receivable, Allowance for Credit Loss, Period Increase (Decrease) | 761.00M | 2025-01-01 → 2025-12-31 |
| Long-Term Debt, Maturity, Year One | 0 | as of 2025-12-31 |
| Current Year Claims and Claims Adjustment Expense | 55.35B | 2025-01-01 → 2025-12-31 |
| Long-Term Debt, Maturity, Year Two | 1.00B | as of 2025-12-31 |
| Long-Term Debt, Maturity, Year Three | 0 | as of 2025-12-31 |
| Prior Year Claims and Claims Adjustment Expense | -1.39B | 2025-01-01 → 2025-12-31 |
| Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims | 53.96B | 2025-01-01 → 2025-12-31 |
| Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid, Current Year | 31.94B | 2025-01-01 → 2025-12-31 |
| Long-Term Debt, Maturity, Year Four | 850.00M | as of 2025-12-31 |
| Liability for Unpaid Claims and Claims Adjustment Expense, Claims Paid, Prior Years | 17.09B | 2025-01-01 → 2025-12-31 |
| Long-Term Debt, Maturity, Year Five | 500.00M | as of 2025-12-31 |
| Long-Term Debt, Maturity, after Year Five | 4.60B | as of 2025-12-31 |
| Debt Securities, Available-for-sale, Allowance for Credit Loss | 0 | as of 2025-12-31 |
| Debt Securities, Available-for-sale, Allowance for Credit Loss, Not Previously Recorded | 0 | 2025-01-01 → 2025-12-31 |
| Debt Securities, Available-for-sale, Allowance for Credit Loss, Writeoff | 0 | 2025-01-01 → 2025-12-31 |
| Reclassification from AOCI, Current Period, Tax | 22.00M | 2025-01-01 → 2025-12-31 |
| Unrecognized Tax Benefits | 0 | as of 2025-12-31 |
| Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value | 105.00M | as of 2025-12-31 |
| Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings | 0 | 2025-01-01 → 2025-12-31 |
| Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases | 8.00M | 2025-01-01 → 2025-12-31 |
| Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales | 0 | 2025-01-01 → 2025-12-31 |
| Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements | -10.00M | 2025-01-01 → 2025-12-31 |
| Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net | 0 | 2025-01-01 → 2025-12-31 |
| Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Period Increase (Decrease) | 18.00M | 2025-01-01 → 2025-12-31 |
| Hybrid Instruments at Fair Value, Net | 1.52B | as of 2025-12-31 |
| Unrealized Gain (Loss) on Hybrid Instrument, Net | 18.00M | 2025-01-01 → 2025-12-31 |
| Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net | 37.32B | as of 2025-12-31 |
| Short-duration Insurance Contracts, Liability for Unpaid Claims and Claims Adjustment Expense, Accumulated Unallocated Claim Adjustment Expense | 2.19B | as of 2025-12-31 |
| Short-duration Insurance Contracts, Liability for Unpaid Claims and Claim Adjustment Expense, Other Reconciling Item | 5.00M | as of 2025-12-31 |
| Debt Securities, Available-for-sale, Amortized Cost | 92.71B | as of 2025-12-31 |
| Statutory Accounting Practices, Statutory Capital and Surplus Required | 1.61B | as of 2025-12-31 |
| Statutory Accounting Practices, Statutory Net Income Amount | 10.64B | 2025-01-01 → 2025-12-31 |
| Statutory Accounting Practices, Statutory Capital and Surplus, Balance | 28.37B | as of 2025-12-31 |
| Statutory Accounting Practices, Statutory Amount Available for Dividend Payments | 9.33B | as of 2025-12-31 |