Investments - Proceeds and Gross Gains/(Losses) (Details) - USD ($) $ in Millions |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2025 |
Jun. 30, 2024 |
Jun. 30, 2025 |
Jun. 30, 2024 |
|
| Investments, Debt and Equity Securities [Abstract] | ||||
| Available for Sale Securities, Gross Realized Gains (Losses), Proceeds on Sales | $ 797 | $ 414 | $ 1,967 | $ 1,010 |
| Debt Securities, Available-for-Sale, Realized Gain | 9 | 7 | 24 | 14 |
| Debt Securities, Available-for-Sale, Realized Loss | $ 5 | $ 5 | $ 32 | $ 26 |