Investments (Rollforward of expected credit-losses, AFS) (Details) - USD ($) $ in Millions |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2026 |
Sep. 30, 2025 |
Sep. 30, 2026 |
Sep. 30, 2025 |
|
| Debt Securities, Available-for-sale, Allowance for Credit Loss [Line Items] | ||||
| Debt Securities, Available-for-Sale, Allowance for Credit Loss, Beginning Balance | $ 48 | $ 71 | $ 52 | $ 70 |
| Debt Securities, Available-for-sale, Allowance for Credit Loss, Period Increase (Decrease) | 21 | 25 | 58 | 76 |
| Debt Securities, Available-for-sale, Allowance for Credit Loss, Writeoff | 0 | (1) | 0 | (2) |
| Debt Securities, Available-for-sale, Allowance for Credit Loss, Recovery | (16) | (45) | (57) | (94) |
| Debt Securities, Available-for-Sale, Allowance for Credit Loss, Ending Balance | $ 53 | $ 50 | $ 53 | $ 50 |