Debt and Interest Expense - Interest Expense Table (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Interest Expense [Abstract]
Current debt, long-term debt, and other	$ 240	$ 238	$ 710	$ 724
Capitalized interest	(63)	(53)	(197)	(163)
Interest expense	$ 177	$ 185	$ 513	$ 561