Debt and Interest Expense - Interest Expense Table (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Interest Expense [Abstract]
Current debt, long-term debt, and other	$ 963,000,000	$ 986,000,000	$ 871,000,000
(Gain) loss on early debt retirements and commitment termination			112,000,000	[1]
Capitalized interest	(221,000,000)	(147,000,000)	(128,000,000)
Interest expense	742,000,000	839,000,000	855,000,000
Table Text Block Supplement [Abstract]
Debt retirements, aggregate principal amount			$ 1,400,000,000

[1] Loss on early debt retirements in 2010 is the result of repurchasing $1.4 billion aggregate principal amount of debt due 2011 and 2012.