Income Taxes Expense (Benefit) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Current tax expense:
Federal	$ 34,455	$ 32,957	$ 38,573
State	2,042	1,126	687
Total	36,497	34,083	39,260
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Federal	12,752	18,523	15,357
State	672	0	(3,532)
Total	13,424	18,523	11,825
Income tax expense	$ 49,921	$ 52,606	$ 51,085