Derivative Financial Instruments - Gains and Losses on Derivative Instruments Designated and Qualifying As Hedging Instruments in Cash Flow Hedges (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in AOCI on Derivatives	$ (201)	$ (17)
Gain (Loss) Reclassified From AOCI into Income	(1)	(1)
Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in AOCI on Derivatives	0	(1)
Foreign exchange contracts | Net interest income
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Reclassified From AOCI into Income	0	0
Interest rate contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in AOCI on Derivatives	(201)	(16)
Interest rate contracts | Net interest income
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Reclassified From AOCI into Income	$ (1)	$ (1)