Deposits - Maturities of Time Deposits (Parenthetical) (Detail) $ in Millions |
Sep. 30, 2021
USD ($)
|
|---|---|
| Deposits [Abstract] | |
| Total domestic time deposits in denominations that met or exceeded the applicable insurance limits, or were otherwise not covered by insurance | $ 19,510 |
| Total foreign time deposits in denominations that met or exceeded the applicable insurance limits, or were otherwise not covered by insurance | $ 31,660 |