Investment Securities - Gross Gains and Losses Realized through Sales of Available-for-Sale Investment Securities (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] | ||||
| Realized gains | $ 1 | $ 0 | $ 8 | $ 3 |
| Realized losses | (58) | (36) | (65) | (37) |
| Net realized gains (losses) | (57) | (36) | (57) | (34) |
| Income tax (benefit) on net realized gains (losses) | $ (14) | $ (9) | $ (14) | $ (8) |