Commitments, Contingencies and Guarantees (Credit Risk Of Financial Instruments By Contractual Amounts) (Details) - USD ($) $ in Millions |
Dec. 31, 2020 |
Dec. 31, 2019 |
Dec. 31, 2018 |
Dec. 31, 2017 |
|---|---|---|---|---|
| Other Commitments [Line Items] | ||||
| Unused commitments to extend credit | $ 56,644 | $ 52,976 | ||
| Standby letters of credit | 1,742 | 1,521 | ||
| Commercial letters of credit | 132 | 59 | ||
| Liabilities associated with standby letters of credit | 25 | 22 | ||
| Assets associated with standby letters of credit | 25 | 23 | ||
| Reserve for unfunded credit commitments | $ 126 | $ 45 | $ 51 | $ 53 |