Derivatives - Schedule of Pretax Effects of Derivative Financial Instruments Designated or Previously Designated as Effective Hedges (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Derivative Instruments, Gain (Loss) [Line Items]
Recognized in OCI (effective portion)	$ 39	$ 56
Reclassified from AOCL to Income	(4)	(1)
Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Recognized in OCI (effective portion)	0	0
Reclassified from AOCL to Income	(2)	(2)
Foreign currency contracts
Derivative Instruments, Gain (Loss) [Line Items]
Recognized in OCI (effective portion)	3	35
Reclassified from AOCL to Income	(2)	1
Cross-currency swaps
Derivative Instruments, Gain (Loss) [Line Items]
Recognized in OCI (effective portion)	36	21
Reclassified from AOCL to Income	$ 0	$ 0