Derivatives and Hedging Activities - Derivatives with Credit-Related Contingent Features (Detail) - USD ($) $ in Millions |
Dec. 31, 2020 |
Dec. 31, 2019 |
|---|---|---|
| Derivative [Line Items] | ||
| Aggregate fair value of derivative contracts which are in net liability position | $ 43,368 | $ 32,800 |
| Aggregate fair value of assets as a collateral for derivative contracts | 35,296 | 28,510 |
| One-Notch Reduction [Member] | ||
| Derivative [Line Items] | ||
| Additional collateral or termination payments pursuant to bilateral agreements with certain counterparties which could have been called by counterparties in the event of a reduction in the firm's long-term credit ratings | 481 | 358 |
| Two-Notch Reduction [Member] | ||
| Derivative [Line Items] | ||
| Additional collateral or termination payments pursuant to bilateral agreements with certain counterparties which could have been called by counterparties in the event of a reduction in the firm's long-term credit ratings | $ 1,388 | $ 1,268 |