CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS (unaudited) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net loss		$ (17,777)	$ (14,717)
Other comprehensive loss:
Foreign currency translation losses	[1]	(19)	(7)
Total other comprehensive loss	[1]	(19)	(7)
Total comprehensive loss		$ (17,796)	$ (14,724)

[1] Net of tax effect which was not material.