Debt and Financing Costs - Components of Financing Costs, Net (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Debt Disclosure [Abstract]
Interest expense	$ 124	$ 141	$ 248	$ 287
Amortization of deferred loan costs	1	2	3	4
Capitalized interest	(90)	(88)	(185)	(178)
Interest income	0	(3)	(4)	(6)
Financing costs, net	$ 35	$ 52	$ 62	$ 107