Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Comprehensive Deficit [Member]
BALANCE at Dec. 31, 2020	$ 58,716	$ 41	$ 279,905	$ (221,230)
BALANCE, Shares at Dec. 31, 2020		41,233,000
Non-cash compensation recognized on stock options and ESPP	18		18
Restricted stock grants, net of cancellations	998	$ 1	997
Restricted stock grants, net of cancellations, shares		970,000
Cancellation of shares for payment of withholding tax	(824)		(824)
Cancellation of shares for payment of withholding tax, shares		(121,000)
Employee stock purchase plan	15		15
Employee stock purchase plan, shares		4,000
Common shares issued in stock offering,net of offering costs	59,898	$ 10	59,888
Common shares issued in stock offering, net offering costs, shares		9,521,000
Exercise of common stock warrants	40		40
Exercise of common stock warrants, shares		33,000
Exercise of stock options	19		19
Exercise of stock options, shares		6,000
Net income (loss)	(3,225)			(3,225)
BALANCE at Mar. 31, 2021	115,655	$ 52	340,058	(224,455)
BALANCE, Shares at Mar. 31, 2021		51,646,000
BALANCE at Dec. 31, 2021	$ 100,560	$ 54	352,779	(252,273)
BALANCE, Shares at Dec. 31, 2021	54,259,390	54,259,000
Non-cash compensation recognized on stock options and ESPP	$ 21		21
Restricted stock grants, net of cancellations	1,045	$ 1	1,044
Restricted stock grants, net of cancellations, shares		1,005,000
Cancellation of shares for payment of withholding tax	(474)		(474)
Cancellation of shares for payment of withholding tax, shares		(121,000)
Employee stock purchase plan	19		19
Employee stock purchase plan, shares		7,000
Exercise of stock options	14		14
Exercise of stock options, shares		6,000
Net income (loss)	(7,002)			(7,002)
BALANCE at Mar. 31, 2022	$ 94,183	$ 55	$ 353,403	$ (259,275)
BALANCE, Shares at Mar. 31, 2022	55,155,755	55,156,000