CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE 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 Comprehensive Income [Abstract]
Net income (loss)	$ 3,470	$ (1,069)	$ (19,166)	$ (13,379)
Other comprehensive income (loss):
Unrealized (loss) gain on investments	(9)	(18)	29	(18)
Comprehensive income (loss)	$ 3,461	$ (1,087)	$ (19,137)	$ (13,397)