Income Taxes (Details 3) (Uncertain Tax Positions [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Uncertain Tax Positions [Member]
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Unrecognized Tax Benefits	$ 11	$ 48	$ 28	$ 81
Additions for tax positions of prior years	0	27	4
Reductions for tax positions of prior years	(2)	(4)	(4)
Additions for tax positions related to the current year	1	1	0
Settlements	(30)	(3)	(53)
Lapse of statute of limitations	$ (6)	$ (1)	$ 0