Income Taxes (Unrecognized Tax Benefits) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Income Tax Expense (Benefit) [Abstract]
Balance at January 1	$ 307	$ 291	$ 404
Increases-prior period positions	127	34	51
Decreases-prior period positions	(107)	(59)	(142)
Increases-current period positions	64	61	43
Decreases-current period positions	(21)	0	0
Prior period positions becoming otherwise deductible in current period	(12)	(16)	(36)
Settlements with tax authorities	0	0	(13)
Expiration of statutes of limitation	(11)	(4)	(16)
Balance at December 31	$ 347	$ 307	$ 291