Debt and Financing Costs - Components of Financing Costs, Net (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Debt Disclosure [Abstract]
Interest expense	$ 116	$ 128
Amortization of deferred loan costs	1	2
Capitalized interest	(26)	(58)
Interest income	(1)	(3)
Financing costs, net	$ 90	$ 69