Income Taxes - Schedule of Changes in Valuation Allowance (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Tax Disclosure [Abstract]
Balance at beginning of year	$ 1,400	$ 1,398	$ 1,268
Increase to allowance	471	45	157
Release of allowance	(41)	(31)	(31)
U.S. state tax apportionment and tax rate changes	(32)	(17)	6
Foreign currency translation	6	5	(2)
Balance at end of year	$ 1,804	$ 1,400	$ 1,398