Income Taxes - Components of Provision (Benefit) for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Federal:
Current	$ (1,266)	$ (758)	$ 1,521
Deferred	380	1,021	(682)
Federal	(886)	263	839
State:
Current	(120)	(145)	585
Deferred	(117)	218	(299)
State	(237)	73	286
(Benefit) provision for income taxes	$ (1,123)	$ 336	$ 1,125