Income Taxes - Schedule of Changes in Valuation Allowance (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Balance at beginning of year	$ 1,668	$ 1,804	$ 1,400
Increase to allowance	472	117	471
Release of allowance	(42)	(77)	(41)
Acquisitions and divestitures (F)	29	(37)
U.S. state tax apportionment and tax rate changes	(45)	(80)	(32)
Foreign currency translation	(45)	(59)	6
Balance at end of year	$ 2,037	$ 1,668	$ 1,804