Commitments and Contingencies - Summary of Contractual Amounts for Unfunded Commitments and Letters of Credit (Detail) - USD ($) $ in Millions |
Mar. 31, 2026 |
Dec. 31, 2025 |
|---|---|---|
| Other Commitments [Line Items] | ||
| Total amount | $ 16,121 | $ 16,831 |
| Commitments to extend credit | ||
| Other Commitments [Line Items] | ||
| Unsecured loan commitments | 1,060 | 1,034 |
| Total amount | 14,642 | 15,420 |
| Credit card guarantees | ||
| Other Commitments [Line Items] | ||
| Total amount | 863 | 813 |
| Standby letters of credit | ||
| Other Commitments [Line Items] | ||
| Unsecured letters of credit | 2 | 2 |
| Total amount | $ 616 | $ 598 |