Asset Retirement Obligations (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012
Asset Retirement Obligation Disclosure [Abstract]
Asset Retirement Obligations, Beginning Balance	$ 402		$ 377
Liabilities Incurred	4		24
Liabilities Settled	(15)		(98)
Revision of Estimate	7		30
Accretion Expense	21	[1]	21	[1]
Other	(2)		(34)
Asset Retirement Obligations, Ending Balance	$ 417		$ 320

[1] Accretion expense is included in DD&A expense in the consolidated statements of operations.