Discontinued Operations (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
Discontinued operations components of earnings and balance sheet disclosure
Income (loss) from discontinued operations, net of tax	$ 1	$ (1)	$ (1)	$ (1)	$ 13	$ 2	$ (4)	$ (71)	$ (2)	$ (60)	$ (24)
Discontinued operations
Discontinued operations components of earnings and balance sheet disclosure
Total net revenues										382	467
Income (loss) from discontinued operations									2	(124)	(40)
Gain on sale									(7)	26
Income tax expense (benefit)									(3)	(38)	(16)
Income (loss) from discontinued operations, net of tax									$ (2)	$ (60)	$ (24)