Income Taxes (Schedule of Unresolved Income Tax Positions) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Balance at beginning of year	$ 366	$ 293
Increases related to current year income tax positions	25	32
Increases related to prior year income tax positions	66	66
Settlements and resolutions of income tax audits	(155)	(15)
Statute of limitations expirations	(53)	(5)
Other		(5)
Balance at end of year	249	366
Current liabilities—Income taxes	21	13
Noncurrent liabilities—Other liabilities	$ 228	$ 353