CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	At-the-Market Offering	Equity Offering	Common Stock	Common Stock At-the-Market Offering	Common Stock Equity Offering	Additional Paid-In Capital	Additional Paid-In Capital At-the-Market Offering	Additional Paid-In Capital Equity Offering	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	1,458						1,458
Issuance of common stock for 401k match (in shares)				25,792
Issuance of common stock for 401(k) match	95						95
Issuance of common stock for restricted stock units (in shares)				25,645
Taxes paid on employees' behalf related to vesting of stock awards	(37)						(37)
Effect of foreign currency translation and unrealized loss on investments	(59)									(59)
Net loss	(10,263)										(10,263)
Balance (in shares) at Sep. 30, 2022				4,933,288
Balance at Sep. 30, 2022	7,220			$ 49			403,799			(234)	(396,394)
Balance (in shares) at Jun. 30, 2022				4,901,246
Balance at Jun. 30, 2022	10,271			$ 49			403,347			(220)	(392,905)
Increase (decrease) in stockholders' equity
Stock-based compensation expense	446						446
Issuance of common stock for 401k match (in shares)				12,875
Issuance of common stock for 401(k) match	29						29
Issuance of common stock for restricted stock units (in shares)				19,167
Taxes paid on employees' behalf related to vesting of stock awards	(23)						(23)
Effect of foreign currency translation and unrealized loss on investments	(14)									(14)
Net loss	(3,489)										(3,489)
Balance (in shares) at Sep. 30, 2022				4,933,288
Balance at Sep. 30, 2022	7,220			$ 49			403,799			(234)	(396,394)
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	1,172						1,172
Issuance of common stock for 401k match (in shares)				40,755
Issuance of common stock for 401(k) match	86			$ 1			85
Issuance of common stock and warrants in equity offering (net of issuance costs) (in shares)					94,665	6,756,710
Issuance of common stock and warrants in equity offering, net of issuance costs		$ 103	$ 5,842		$ 1	$ 68		$ 102	$ 5,774
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)	47,808			47,808
Issuance of common stock for director compensation	$ 37						37
Effect of foreign currency translation and unrealized loss on investments	(18)									(18)
Net loss	(11,189)										(11,189)
Balance (in shares) at Sep. 30, 2023				11,901,780
Balance at Sep. 30, 2023	392			$ 119			411,406			(247)	(410,886)
Balance (in shares) at Jun. 30, 2023				6,100,263
Balance at Jun. 30, 2023	587			$ 61			407,930			(244)	(407,160)
Increase (decrease) in stockholders' equity
Stock-based compensation expense	367						367
Issuance of common stock for 401k match (in shares)				13,739
Issuance of common stock for 401(k) match	$ 30						30
Issuance of common stock and warrants in equity offering (net of issuance costs) (in shares)						5,750,000
Issuance of common stock and warrants in equity offering, net of issuance costs			$ 3,125			$ 58			$ 3,067
Issuance of common stock for director compensation (in shares)	37,778			37,778
Issuance of common stock for director compensation	$ 12						12
Effect of foreign currency translation and unrealized loss on investments	(3)									(3)
Net loss	(3,726)										(3,726)
Balance (in shares) at Sep. 30, 2023				11,901,780
Balance at Sep. 30, 2023	$ 392			$ 119			$ 411,406			$ (247)	$ (410,886)