CONSOLIDATED STATEMENTS OF CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit	Series A Convertible Preferred Stock	Series A Convertible Preferred Stock Preferred Stock	Series A Convertible Preferred Stock Common Stock	Series A Convertible Preferred Stock Additional Paid-In Capital	Series B Convertible Preferred Stock	Series B Convertible Preferred Stock Common Stock	Series B Convertible Preferred Stock Additional Paid-In Capital
Balance at Dec. 31, 2019	$ (4,085)	$ 9	$ 360,926	$ (126)	$ (364,894)		$ 0
Balance (in shares) at Dec. 31, 2019		933,423					796
Increase (decrease) in stockholders' equity
Stock-based compensation expense	864		864
Issuance of common stock for 401(k) match	$ 112		112
Issuance of common stock for 401k match (in shares)	20,788	20,788
Issuance of stock for restricted stock unit vesting, net of shares withheld for employee taxes	$ 0		0
Issuance of stock for restricted stock unit vesting, net of shares withheld for employee taxes (in shares)		6,006
Taxes paid on employees' behalf related to vesting of stock awards	(17)		(17)
Issuance of common stock for warrant exercises	1,658	$ 2	1,656
Issuance of common stock for warrant exercises (in shares)		207,296
Issuance of stock	5,305	$ 13	5,292			$ 0		$ 2	$ (2)	$ 0	$ 7	$ (7)
Issuance of stock (in shares)		1,348,285					(796)	99,500			718,750
Reclassification of warrant liability to equity	15,934		15,934
Effect of foreign currency translation	(33)			(33)
Net loss	(10,206)				(10,206)
Balance at Dec. 31, 2020	9,532	$ 33	384,758	(159)	(375,100)		$ 0
Balance (in shares) at Dec. 31, 2020		3,334,048					0
Series B Convertible Preferred Stock, balance at Dec. 31, 2019	$ 0
Series B Convertible Preferred Stock, balance (in shares) at Dec. 31, 2019	5,750
Increase (Decrease) in Temporary Equity
Issuance of common stock upon conversion of Series B Convertible Preferred Stock (in shares)	(5,750)
Issuance of preferred stock in connection with private offering (in shares)	0
Series B Convertible Preferred Stock, balance at Dec. 31, 2020	$ 0
Series B Convertible Preferred Stock, balance (in shares) at Dec. 31, 2020	0
Increase (decrease) in stockholders' equity
Stock-based compensation expense	$ 1,685		1,685
Issuance of common stock for 401(k) match	$ 109		109
Issuance of common stock for 401k match (in shares)	13,611	13,611
Issuance of stock for restricted stock unit vesting, net of shares withheld for employee taxes	$ 0		0
Issuance of stock for restricted stock unit vesting, net of shares withheld for employee taxes (in shares)		12,219
Taxes paid on employees' behalf related to vesting of stock awards	(102)		(102)
Issuance of common stock for warrant exercises	3,856	$ 5	3,851
Issuance of common stock for warrant exercises (in shares)		481,973
Issuance of stock	11,993	$ 11	11,982
Issuance of stock (in shares)		1,040,000
Effect of foreign currency translation	(16)			(16)
Net loss	(11,031)				(11,031)
Balance at Dec. 31, 2021	16,026	$ 49	$ 402,283	$ (175)	$ (386,131)		$ 0
Balance (in shares) at Dec. 31, 2021		4,881,851					0
Series B Convertible Preferred Stock, balance at Dec. 31, 2021	$ 0
Series B Convertible Preferred Stock, balance (in shares) at Dec. 31, 2021	0