Interest Expense Table (Detail) (USD $)	3 Months Ended				9 Months Ended
	Sep. 30, 2011		Sep. 30, 2010		Sep. 30, 2011		Sep. 30, 2010
Interest Expense [Abstract]
Current debt, long-term debt, and other	$ 245,000,000	[1]	$ 235,000,000	[1]	$ 743,000,000	[1]	$ 642,000,000	[1]
Loss on early debt retirements and commitment termination			17,000,000	[2]			89,000,000	[2]
Capitalized interest	(39,000,000)		(34,000,000)		(101,000,000)		(89,000,000)
Interest expense	206,000,000		218,000,000		642,000,000		642,000,000
Table Text Block Supplement [Abstract]
Unamortized debt issuance costs associated with the retirement of the Midstream Subsidiary Note			7,000,000				9,000,000
Debt retirements, aggregate principal amount							1,000,000,000
Commitment and structuring costs associated with a previously contemplated term-loan facility			$ 17,000,000				$ 17,000,000

[1] Included in the three and nine months ended September 30, 2010, is $7 million and $9 million, respectively, of unamortized debt issuance costs associated with the retirement of the midstream subsidiary note payable to a related party (Midstream Subsidiary Note).

[2] Loss on early debt retirements in 2010 is the result of repurchasing $1.0 billion aggregate principal amount of debt due 2011 and 2012. Also included in the three and nine months ended September 30, 2010, is $17 million for commitment and structuring costs associated with a contemplated term-loan facility.