Income Taxes - Valuation Allowances Rollforward (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Balance at January 1	$ (864)	$ (818)	$ (922)
Valuation Allowance [Line Items]
Balance at December 31	(1,403)	(864)	(818)
U.S. Foreign Tax Credits [Member]
Valuation Allowance [Line Items]
Change in valuation allowances	(384)	11	58
Foreign and State Net Operating Loss Carryforwards [Member]
Valuation Allowance [Line Items]
Change in valuation allowances	10	64	(57)
Foreign Capitalized Costs [Member]
Valuation Allowance [Line Items]
Change in valuation allowances	$ (165)	$ (121)	$ 103