Valuation and Qualifying Accounts (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Allowance for doubtful accounts and for notes receivable [Member]
Valuation And Qualifying Accounts
Beginning Balance	$ 1	[1],[2]	$ 15	[1]	$ 22	[1]
Additions Charged (Credited) To Cost and Expenses	0	[2]	1	[1]	(6)	[1]
Additions Other	0	[2]	0	[1]	0	[1]
Deductions	1	[2],[3]	15	[1],[4]	1	[1],[3]
Ending Balance	0	[2]	1	[1],[2]	15	[1]
Deferred Tax Asset Valuation Allowance [Member]
Valuation And Qualifying Accounts
Beginning Balance	145	[2],[5]	249	[5]	289	[5]
Additions Charged (Credited) To Cost and Expenses	(1)	[2]	(33)	[5]	(40)	[5]
Additions Other	0	[2]	0	[5]	0	[5]
Deductions	0	[2]	71	[4],[5]	0	[5]
Ending Balance	144	[2]	145	[2],[5]	249	[5]
Price Risk Management Credit Reserves Liabilities [Member]
Valuation And Qualifying Accounts
Beginning Balance					(3)	[6]
Additions Charged (Credited) To Cost and Expenses					3	[6],[7]
Additions Other					0	[6]
Deductions					0	[6]
Ending Balance					$ 0	[6]

[1] Deducted from related assets, primarily included in assets of discontinued operations.

[2] Deducted from related assets.

[3] Represents balances written off, reclassifications, and recoveries.

[4] Includes balance deductions due to the spin-off of our exploration and production business on December 31, 2011.

[5] Deducted primarily from related assets, with a portion included in assets of discontinued operations.

[6] Deducted from related liabilities, included in liabilities of discontinued operations.

[7] Included in income (loss) from discontinued operations.