Assets Held for Sale Income Statements (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Assets Held for Sale Income Statement [Abstract]
Revenues									$ 0		$ 84		$ 152
Disposal Group, Including Discontinued Operation, Operating Expense									(3)	[1]	54	[1]	(134)	[1]
(Loss) income before income tax expense and equity in net income from unconsolidated investments									(3)		138		20
Equity in net income from unconsolidated investments									2		8		24
Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	0	0	(2)	0	(1)	(7)	2	149	(2)		143		36
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax									$ 0		$ 119		$ (8)

[1] (1)During the years ended December 31, 2012, 2011 and 2010, we recorded a net after-tax (loss) gain on disposal of assets held for sale of $0, $119 million and $(8) million, respectively.