Collateralized Agreements and Financings - Financial Instruments Received as Collateral and Repledged (Detail) - USD ($) $ in Millions |
Dec. 31, 2020 |
Dec. 31, 2019 |
|---|---|---|
| Collateralized Agreements And Financings [Abstract] | ||
| Financial instruments at fair value received as collateral by the firm that it was permitted to deliver or repledge | $ 864,494 | $ 661,490 |
| Financial instruments at fair value received as collateral which the firm delivered or repledged | $ 723,409 | $ 558,634 |