Income Taxes - Reconciliation of Liabilities Associated with Uncertain Tax Provisions (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Balance at beginning of year	$ 1,285	$ 1,402	$ 1,452
Additions based on tax positions related to the current year	70	140	154
Additions for tax positions of prior years	119	136	96
Additions related to acquisitions	127	5	43
Impact of changes in exchange rates	(25)	(78)	(62)
Settlements with tax authorities	(45)	(99)	(27)
Reductions for tax positions of prior years	(85)	(203)	(212)
Reductions due to the lapse of the applicable statute of limitations	(27)	(18)	(42)
Balance at end of year	$ 1,419	$ 1,285	$ 1,402