Debt and Financing Costs - Components of Financing Costs, Net (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Debt Disclosure [Abstract]
Interest expense	$ 116	$ 116
Amortization of deferred loan costs	2	1
Capitalized interest	(14)	(11)
Loss on extinguishment of debt	1	0
Interest income	(5)	(1)
Financing costs, net	$ 100	$ 105