CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (49,577)	$ (37,323)	$ (92,427)	$ (10,136)
Unrealized gains on investments, net of tax	1,016	10	1,393	222
Currency translation adjustment	74	(93)	83	(8)
Comprehensive loss	$ (48,487)	$ (37,406)	$ (90,951)	$ (9,922)