CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS (Unaudited) [Abstract]
Net loss	$ (4,130)	$ (6,450)	$ (9,738)	$ (14,055)
Other comprehensive income (loss):
Change in unrealized gain on investments, net of tax	0	(1)	1	0
Total other comprehensive income gain (loss)	0	(1)	1	0
Comprehensive loss	$ (4,130)	$ (6,451)	$ (9,737)	$ (14,055)