Valuation and Qualifying Accounts (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Allowance for doubtful accounts and for notes receivable [Member]
Valuation And Qualifying Accounts
Beginning Balance	$ 15	[1]	$ 22	[1]	$ 29	[1]
Additions Charged (Credited) To Cost and Expenses	1	[1]	(6)	[1]	4	[1]
Additions Other	0	[1]	0	[1]	0	[1]
Deductions	15	[1],[2]	1	[1],[3]	11	[1],[3]
Ending Balance	1	[1]	15	[1]	22	[1]
Deferred Tax Asset Valuation Allowance [Member]
Valuation And Qualifying Accounts
Beginning Balance	249	[4]	289	[4]	224	[4]
Additions Charged (Credited) To Cost and Expenses	(33)	[4]	(40)	[4]	65	[4]
Additions Other	0	[4]	0	[4]	0	[4]
Deductions	71	[2],[4]	0	[4]	0	[4]
Ending Balance	145	[4]	249	[4]	289	[4]
Price Risk Management Credit Reserves Assets [Member]
Valuation And Qualifying Accounts
Beginning Balance					6	[1]
Additions Charged (Credited) To Cost and Expenses					(3)	[1],[5]
Additions Other					(3)	[1],[6]
Deductions					0	[1]
Ending Balance					0	[1]
Price Risk Management Credit Reserves Liabilities [Member]
Valuation And Qualifying Accounts
Beginning Balance			(3)	[7]	(15)	[7]
Additions Charged (Credited) To Cost and Expenses			3	[5],[7]	12	[5],[7]
Additions Other			0	[7]	0	[7]
Deductions			0	[7]	0	[7]
Ending Balance			$ 0	[7]	$ (3)	[7]

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

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

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

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

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

[6] Included in accumulated other comprehensive income (loss).

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