Income Taxes - Summary of provision for income taxes from continuing operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Current income tax:
Federal	$ 0	$ 61
State	122	167
Foreign	227	211
Total current	349	439
Deferred income tax:
Federal	4,029	768
State	(381)	(60)
Total deferred	3,648	708
Provision for income taxes	$ 3,997	$ 1,147