CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net loss	$ (43,609)	$ (90,419)	$ (157,957)
Other comprehensive income (loss):
Foreign currency translation adjustment	24	10,145	(4,447)
Unrealized gain (loss) on marketable securities, net of tax	(13)	54	(747)
Total comprehensive loss	$ (43,598)	$ (80,220)	$ (163,151)