UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Statement of Comprehensive Income [Abstract]
Net Loss	$ (7,581)	$ (7,350)	$ (23,733)	$ (22,227)
Unrealized Gain (Loss) on Available-for-Sale Debt Instrument Investments	4	2	(4)	(11)
Foreign Currency Translation Adjustments	0	1	3	8
Comprehensive Loss	$ (7,577)	$ (7,347)	$ (23,734)	$ (22,230)