Income Taxes (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Income Tax Disclosure [Abstract]
Effective tax rate (as a percent)	37.80%	37.80%	37.90%	37.60%
Federal statutory rate (as a percent)	35.00%	35.00%	35.00%	35.00%
Unrecognized tax benefit, if recognized, would affect the effective tax rate	$ 2.8		$ 2.8
Maximum reduction in unrecognized tax benefits due to expiration of statutes of limitation and audit settlements in next 12 months	$ 2.6		$ 2.6