Investment securities - Pre-Tax Net Securities Gains (Losses) by Type (Details) - USD ($) $ in Millions |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2026 |
Jun. 30, 2025 |
Jun. 30, 2026 |
Jun. 30, 2025 |
|
| Schedule of Investment Income, Reported Amounts, by Category [Line Items] | ||||
| Total net investment securities gains (losses) | $ (25) | $ (35) | $ (75) | $ (35) |
| Non-U.S. government | ||||
| Schedule of Investment Income, Reported Amounts, by Category [Line Items] | ||||
| Total net investment securities gains (losses) | (11) | (28) | (32) | (28) |
| Foreign covered bonds | ||||
| Schedule of Investment Income, Reported Amounts, by Category [Line Items] | ||||
| Total net investment securities gains (losses) | (14) | (4) | (25) | (4) |
| Other | ||||
| Schedule of Investment Income, Reported Amounts, by Category [Line Items] | ||||
| Total net investment securities gains (losses) | $ 0 | $ (3) | $ (18) | $ (3) |