Income Taxes (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Income Taxes
Income tax provision (benefit)	$ 19,067,000	$ 9,679,000	$ 30,421,000	$ 18,795,000
Effective tax rate (as a percent)	40.00%	38.50%	40.60%	38.30%
Unrecognized tax benefits, including related interest and penalties			5,600,000
Unrecognized tax benefits that would impact the effective tax rate	5,000,000		5,000,000
Unrecognized tax benefits interest that would impact the effective tax rate	$ 600,000		$ 600,000