Accumulated Other Comprehensive Income (Loss) - Changes in Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance			$ 29,150	$ 28,580
Other comprehensive income (loss)	$ 102	$ (86)	141	(112)
Balance	29,616	28,635	29,616	28,635
Foreign Currency Translation Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	(681)	(478)	(721)	(452)
Other comprehensive income (loss)	102	(87)	142	(113)
Balance	(579)	(565)	(579)	(565)
Other [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	4	4	5	4
Other comprehensive income (loss)		1	(1)	1
Balance	4	5	4	5
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	(677)	(474)	(716)	(448)
Other comprehensive income (loss)	102	(86)	141	(112)
Balance	$ (575)	$ (560)	$ (575)	$ (560)