Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Change in Accounting Estimate [Line Items]
Income tax expense (benefit)	$ 6,862	$ 7,092	$ 18,781	$ 17,593
Effective tax rate	34.10%	36.30%	36.40%	34.30%
Expected effective income tax rate for the year			36.70%
Statutory federal tax rate			35.00%
Investment Tax Credit Carryforward [Member]
Change in Accounting Estimate [Line Items]
Income tax expense (benefit)				$ (700)