Income Taxes (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Income Taxes
Effective tax rate	37.90%	38.30%	37.90%	38.20%
Uncertain tax positions	$ 0.1		$ 0.1
Unrecognized tax positions that, if recognized, would affect the effective tax rate	$ 0.1		$ 0.1