CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - 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	$ (14,871)	$ (17,562)	$ (31,337)	$ (36,354)
Other comprehensive income
Unrealized gains on available-for-sale investments, net of taxes	1,248	161	1,011	372
Comprehensive loss	$ (13,623)	$ (17,401)	$ (30,326)	$ (35,982)