Income Taxes (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Income Taxes [Line Items]
Effective tax rate	32.10%	33.20%
Overall decrease in unrecognized tax benefits (UTPs)	$ (83.0)	$ 12.2
Gross [Member]
Income Taxes [Line Items]
Overall decrease in unrecognized tax benefits (UTPs)	83.0
Net [Member]
Income Taxes [Line Items]
Overall decrease in unrecognized tax benefits (UTPs)	$ 50.7