Condensed Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net Loss	$ (25,155)	$ (9,527)	$ (44,220)	$ (15,635)
Other comprehensive income, net of tax:
Unrealized gain (loss) on short-term investments, net of tax	(6)	(7)	15	(7)
Comprehensive Net Loss	$ (25,161)	$ (9,534)	$ (44,205)	$ (15,642)