Income Taxes (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Income Taxes [Line Items]
Gross unrecognized tax benefits	$ 66		$ 66
Accrued interest and penalties	13		13
Income tax examination, years under examination			2002 to 2010
Effective tax rate	26.90%	27.40%	27.20%	28.00%
Charge to write-off deferred tax assets			5.8
Uncertain tax positions reserve adjustments			3
Other Current Liabilities [Member]
Income Taxes [Line Items]
Gross unrecognized tax benefits	2		2
Other Liabilities [Member]
Income Taxes [Line Items]
Gross unrecognized tax benefits	$ 64		$ 64