Income Taxes - Components of Income Tax Expense (Benefit) Table (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Current income tax expense (benefit)
Federal income tax expense (benefit)	$ 4,477	$ 32,422	$ (114)
State income tax expense (benefit)	1,340	1,764	493
Total current income tax expense (benefit)	5,817	34,186	379
Deferred income tax expense (benefit)
Federal income tax expense (benefit)	1,622	10,251	35,361
State income tax expense (benefit)	933	1,095	3,321
Total deferred income tax expense (benefit)	2,555	11,346	38,682
Total income tax expense (benefit)	$ 8,372	$ 45,532	$ 39,061