Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Current Income Taxes:
Federal	$ 26,927	$ (15,384)	$ 24,389
State	89	40	177
Current Income Tax Expense (Benefit), Total	27,016	(15,344)	24,566
Deferred Income Taxes:
Federal	1,681	552	(602)
Deferred Income Tax Expense (Benefit), Total	1,681	552	(602)
Total income tax expense (benefit)	$ 28,697	$ (14,792)	$ 23,964