Amount and Location in the Income Statement for Derivatives Designed as Cash Flow Hedges (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Derivative Instruments in Cash Flow Hedging Relationships
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivative	$ 20	$ 412	$ 137	$ 277
Derivative Instruments in Cash Flow Hedging Relationships | Interest rate contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivative	(2)	1	11	2
Derivative Instruments in Cash Flow Hedging Relationships | Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivative	22	411	126	275
Non-derivative Instruments in Net Investment Hedging Relationships
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivative	(67)	218	6	138
Non-derivative Instruments in Net Investment Hedging Relationships | Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivative	$ (67)	$ 218	$ 6	$ 138