Allowance for Doubtful Accounts (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011		Dec. 31, 2010
Allowance for Doubtful Accounts [Abstract]
Recovery of Ecuador Receivable	$ 0	$ 19	[1]	$ 6
Allowance for doubtful accounts [Rollforward]
Balance, Beginning of Period	9	27		31
Changes in Ecuador Receivables, Net	0	(19)	[1]	(6)
Other Changes	1	1		2
Net Changes	1	(18)		(4)
Balance, End of Period	$ 10	$ 9		$ 27

[1] During 2011, recovery of approximately $19 million for outstanding receivables 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.