Income Taxes (Details 3) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Unrecognized Tax Benefits, Increases Resulting from Prior Period Tax Positions		$ 53
Uncertain Tax Positions [Member]
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Unrecognized Tax Benefits	48	28	81	72
Unrecognized Tax Benefits, Increases Resulting from Prior Period Tax Positions	27	4	15
Unrecognized Tax Benefits, Decreases Resulting from Prior Period Tax Positions	(4)	(4)	(5)
Unrecognized Tax Benefits, Increases Resulting from Current Period Tax Positions	1	0	7
Unrecognized Tax Benefits, Decreases Resulting from Settlements with Taxing Authorities	(3)	(53)	(5)
Unrecognized Tax Benefits, Reductions Resulting from Lapse of Applicable Statute of Limitations	$ (1)	$ 0	$ (3)