Income Taxes - Summary of provision for income taxes from continuing operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Current income tax:
Federal	$ 0	$ 0
State	293	122
Foreign	41	227
Total current	334	349
Deferred income tax:
Federal	12,004	4,029
State	1,805	(381)
Total deferred	13,809	3,648
Provision for income taxes	$ 14,143	$ 3,997