Amount and Location in the Income Statement for Derivatives Designed as Cash Flow Hedges (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Derivative Instruments in Cash Flow Hedging Relationships
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivative (Effective Portion)	$ (141)	$ (27)	$ (431)	$ (39)
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 (Effective Portion)	0	0	0	(3)
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 (Effective Portion)	(141)	(27)	(431)	(36)
Non-derivative Instruments in Net Investment Hedging Relationships
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivative (Effective Portion)	(142)	(7)	(389)	(30)
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 (Effective Portion)	$ (142)	$ (7)	$ (389)	$ (30)