Investments - Investment Gains and Losses (Details) - USD ($) $ in Millions |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2025 |
Sep. 30, 2024 |
Sep. 30, 2025 |
Sep. 30, 2024 |
|
| Investments [Abstract] | ||||
| Net investment gains (losses), before income taxes | $ 26 | $ (921) | $ 76 | $ (2,805) |