Income Taxes (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Income Taxes
Income tax expense	$ 4,060	$ 2,644	$ 9,027	$ 10,810
Effective income tax rate (as a percent)	38.70%	37.30%	39.40%	37.90%
Federal statutory rate (as a percent)			35.00%	35.00%