Debt and Financing Costs - Components of Financing Costs, Net (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Debt Disclosure [Abstract]
Interest expense	$ 126	$ 142	$ 374	$ 429
Amortization of deferred loan costs	2	2	5	6
Capitalized interest	(85)	(91)	(270)	(268)
Interest income	(2)	(3)	(6)	(10)
Financing costs, net	$ 41	$ 50	$ 103	$ 157