Income Tax - Provision (Benefit) for Income Tax (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Federal:
Current	$ 0	$ 0	$ 0
Deferred	7,694	416	(3,868)
State:
Current	43	3	5
Deferred	269	(380)	488
Foreign:
Current	0	0	0
Deferred	(129)	(174)	(159)
Total Federal, State and Foreign	7,877	(135)	(3,534)
Change in valuation allowance	(14,037)	138	3,539
Income tax provision (benefit)	$ (6,160)	$ 3	$ 5