Allowance for Doubtful Accounts (Details) (Allowance for Sales Returns [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Allowance for Sales Returns [Member]
Allowance for doubtful accounts [Rollforward]
Balance at beginning of period	$ 27		$ 31		$ 97
Allowance for Ecuador receivable	0		1		14
Recovery of Ecuador receivable	(19)	[1]	(7)	[1]	(46)	[1]
Allowance for SemCrude L.P. receivable	0		0		12
Other changes	1		2		2
Net changes before write-offs	(18)		(4)		(18)
Write-off of SemCrude L.P. receivable	0	[2]	0	[2]	(49)	[2]
Other write-offs	0		0		1
Balance at end of period	$ 9		$ 27		$ 31

[1] During 2011, recovery of approximately $19 million for outstanding receivable was included in the final terms of our agreement to transfer our assets and the associated electricity concession and PSC to the Ecuadorian government. See Note 3. Acquisitions and Divestitures. Amount in 2009 was received in accordance with the terms of a settlement agreement and included as a reduction in electricity generation expense.

[2] SemCrude, L.P. was a crude oil purchaser who filed a voluntary petition for reorganization under Chapter 11 of the Bankruptcy Code in 2008.