CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Other Comprehensive Income [Abstract]
Net loss	$ (51,550)	$ (30,935)	$ (32,450)
Other comprehensive (loss) income:
Foreign currency translation adjustment	111	(1)	32
Gain (loss) on investments in available-for-sale-securities	121	(11)	(7)
Total other comprehensive income (loss)	232	(12)	25
Comprehensive loss	$ (51,318)	$ (30,947)	$ (32,425)