CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Balance (in shares) at Dec. 31, 2021		4,881,851
Balance at Dec. 31, 2021	$ 16,026	$ 49	$ 402,283	$ (175)	$ (386,131)
Increase (decrease) in stockholders' equity
Stock-based compensation expense	523		523
Issuance of common stock for 401k match (in shares)		5,074
Issuance of common stock for 401(k) match	25		25
Issuance of common stock for restricted stock units (in shares)		6,478
Taxes paid on employees' behalf related to vesting of stock awards	(14)		(14)
Effect of foreign currency translation and unrealized loss on investments	(18)			(18)
Net loss	(3,331)				(3,331)
Balance (in shares) at Mar. 31, 2022		4,893,403
Balance at Mar. 31, 2022	13,211	$ 49	402,817	(193)	(389,462)
Balance (in shares) at Dec. 31, 2022		4,944,202
Balance at Dec. 31, 2022	4,400	$ 49	404,277	(229)	(399,697)
Increase (decrease) in stockholders' equity
Stock-based compensation expense	424		424
Issuance of common stock for 401k match (in shares)		17,578
Issuance of common stock for 401(k) match	30	$ 1	29
Issuance of common stock under At-the-Market offering (net of issuance costs) (in shares)		94,665
Issuance of common stock under At-the-Market offering (net of issuance costs)	103	$ 1	102
Issuance of common stock for restricted stock units (in shares)		17,640
Taxes paid on employees' behalf related to vesting of stock awards	$ (41)		(41)
Issuance of common stock for director compensation (in shares)	4,472	4,472
Issuance of common stock for director compensation	$ 12		12
Effect of foreign currency translation and unrealized loss on investments	(3)			(3)
Net loss	(3,782)				(3,782)
Balance (in shares) at Mar. 31, 2023		5,078,557
Balance at Mar. 31, 2023	$ 1,143	$ 51	$ 404,803	$ (232)	$ (403,479)