CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net loss	$ (1,069)	$ (5,407)	$ (13,379)	$ (17,573)
Other comprehensive loss:
Net change in unrealized loss on investments	(18)	0	(18)	0
Comprehensive loss	$ (1,087)	$ (5,407)	$ (13,397)	$ (17,573)