Income Taxes - Provision for Income Tax (Benefit) Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current:
Federal	$ 4,305	$ 7,418	$ (22,416)
State		48	(64)
Total	4,305	7,466	(22,480)
Deferred:
Federal	488	(23,512)	29,796
State	(5,529)	(1,835)	(169)
Total	(5,041)	(25,347)	29,627
Total income tax (benefit) expense	$ (736)	$ (17,881)	$ 7,147