Reinsurance and Indemnification - Schedule of Effects of Reinsurance Ceded and Indemnification Programs on Property and Casualty Insurance Claims and Claims Expense and Accident, Health and Other Policy Benefits (Details) - USD ($) $ in Millions |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2026 |
Jun. 30, 2025 |
Jun. 30, 2026 |
Jun. 30, 2025 |
|
| Income Statement Location [Axis]: us-gaap:PolicyholderBenefitsAndClaimsIncurredNet | ||||
| Reductions to costs and expenses due to reinsurance ceded amounts | ||||
| Ceded losses incurred | $ 214 | $ (141) | $ (53) | $ (1,826) |
| Income Statement Location [Axis]: all:AccidentAndHealthInsuranceContractBenefitsNetOfReinsuranceRecoveries | ||||
| Reductions to costs and expenses due to reinsurance ceded amounts | ||||
| Ceded losses incurred | $ (106) | $ (9) | $ (217) | $ (28) |