Deposits - Maturities of Time Deposits (Parenthetical) (Detail) $ in Millions |
Dec. 31, 2020
USD ($)
|
|---|---|
| Deposits [Abstract] | |
| Total domestic time deposits in denominations that met or exceeded the applicable insurance limits, or were otherwise not covered by insurance | $ 11,710 |
| Total foreign time deposits in denominations that met or exceeded the applicable insurance limits, or were otherwise not covered by insurance | $ 12,250 |