Derivatives and Foreign Currency Operations - Schedule of Pretax Effects of Derivative Financial Instruments Designated or Previously Designated as Effective Hedges (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Recognized in OCI	$ (88)	$ (16)	$ 22
Reclassified from AOCL to Income	6	7	(43)
Interest rate swap
Derivative Instruments, Gain (Loss) [Line Items]
Recognized in OCI	0	0	0
Reclassified from AOCL to Income	(7)	(8)	(27)
Foreign exchange contract
Derivative Instruments, Gain (Loss) [Line Items]
Recognized in OCI	4	(16)	24
Reclassified from AOCL to Income	13	15	(13)
Cross-currency swaps
Derivative Instruments, Gain (Loss) [Line Items]
Recognized in OCI	(92)	0	(2)
Reclassified from AOCL to Income	$ 0	$ 0	$ (3)