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, 2026 |
Jun. 30, 2025 |
Jun. 30, 2026 |
Jun. 30, 2025 |
|
| Investments, Debt and Equity Securities [Abstract] | ||||
| Realized gains | $ 3 | $ 1 | $ 4 | $ 8 |
| Realized losses | (52) | (58) | (88) | (65) |
| Net realized gains (losses) | (49) | (57) | (84) | (57) |
| Income tax expense (benefit) on net realized gains (losses) | $ (12) | $ (14) | $ (21) | $ (14) |