CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS [Abstract]
Net loss	$ (17,278)	$ (28,569)	$ (29,234)
Other comprehensive gain (loss), net of tax:
Change in equity adjustment from foreign currency translation, net of tax	0	3	(1)
Change in unrealized gain (loss) on investments, net of tax	(1)	4	(3)
Total other comprehensive income (loss), net of tax	(1)	7	(4)
Comprehensive loss	$ (17,279)	$ (28,562)	$ (29,238)