Financial Instruments - Fair Values of Derivatives (Detail) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Derivative Assets, Total	$ 113	$ 77	[1]
Derivative Liabilities, Total	(126)	(98)	[1]
Derivatives Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets, Total	77	60
Derivative Liabilities, Total	(105)	(71)
Derivatives Designated as Hedging Instruments [Member] | Foreign Exchange Derivatives [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets, Total	71	53
Derivative Liabilities, Total	(74)	(55)
Derivatives Designated as Hedging Instruments [Member] | Interest Rate Derivatives [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets, Total	6	7
Derivative Liabilities, Total	(31)	(16)
Derivatives Not Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets, Total	36	17
Derivative Liabilities, Total	(21)	(27)
Derivatives Not Designated as Hedging Instruments [Member] | Foreign Exchange Derivatives [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets, Total	33	13
Derivative Liabilities, Total	(18)	(22)
Derivatives Not Designated as Hedging Instruments [Member] | Interest Rate Derivatives [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets, Total	3	4
Derivative Liabilities, Total	$ (3)	$ (5)

[1] 2017 figures have been recast following the retrospective adoption on January 1, 2018, of the updated accounting standard for revenue recognition (ASC 606).