CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net loss		$ (91,581)	$ (73,859)	$ (154,740)
Other comprehensive loss:
Foreign currency translation gains (losses)	[1]	5,652	(157)	(306)
Total other comprehensive income (loss)	[1]	5,652	(157)	(306)
Total comprehensive loss		$ (85,929)	$ (74,016)	$ (155,046)

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