Loans and asset quality - Nonperforming Assets (Details) - USD ($) $ in Millions |
Jun. 30, 2026 |
Dec. 31, 2025 |
|---|---|---|
| Nonperforming Assets [Line Items] | ||
| With an allowance | $ 22 | $ 131 |
| Without an allowance | 9 | 9 |
| Total | 31 | 140 |
| With an allowance, Other assets owned | 0 | 0 |
| Without an allowance, Other assets owned | 2 | 3 |
| Other assets owned | 2 | 3 |
| With an allowance, Total nonperforming assets | 22 | 131 |
| Without an allowance, Total nonperforming assets | 11 | 12 |
| Total nonperforming assets | 33 | 143 |
| Commercial real estate | ||
| Nonperforming Assets [Line Items] | ||
| With an allowance | 0 | 106 |
| Without an allowance | 0 | 0 |
| Total | 0 | 106 |
| Other residential mortgages | ||
| Nonperforming Assets [Line Items] | ||
| With an allowance | 13 | 16 |
| Without an allowance | 2 | 1 |
| Total | 15 | 17 |
| Wealth management mortgages | ||
| Nonperforming Assets [Line Items] | ||
| With an allowance | 9 | 9 |
| Without an allowance | 7 | 8 |
| Total | $ 16 | $ 17 |