Collateralized Agreements and Financings - Resale and Repurchase Agreements and Securities Borrowed and Loaned Transactions (Parenthetical) (Detail) - USD ($) $ in Millions |
Dec. 31, 2020 |
Dec. 31, 2019 |
|---|---|---|
| Collateralized Agreements And Financings [Abstract] | ||
| Securities borrowed at fair value | $ 28,898 | $ 26,279 |
| Securities loaned at fair value | $ 1,053 | $ 714 |