Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Change in Accounting Estimate [Line Items]
Income tax expense (benefit)	$ 6,873	$ 6,034	$ 11,919	$ 10,501
Effective tax rate	38.20%	34.70%	37.90%	33.10%
Expected effective income tax rate for the year			37.90%
Statutory federal tax rate			35.00%
Investment Tax Credit Carryforward [Member]
Change in Accounting Estimate [Line Items]
Income tax expense (benefit)				$ (700)