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, 2019	$ 48,684	$ 38	$ 274,041	$ (225,395)
BALANCE, Shares at Dec. 31, 2019		38,475,000
Non-cash compensation recognized on stock options and ESPP	13		13
Restricted stock grants, net of cancellations	619	$ 1	618
Restricted stock grants, net of cancellations, shares		1,000,000
Cancellation of shares for payment of withholding tax	(571)		(571)
Cancellation of shares for payment of withholding tax, shares		(110,000)
Employee stock purchase plan	5		5
Employee stock purchase plan, shares		2,000
Exercise of common stock warrants	2,045	$ 1	2,044
Exercise of common stock warrants, shares		1,009,000
Exercise of stock options	13		13
Exercise of stock options, shares		7,000
Net income (loss)	2,045			2,045
BALANCE at Mar. 31, 2020	52,853	$ 40	276,163	(223,350)
BALANCE, Shares at Mar. 31, 2020		40,383,000
BALANCE at Dec. 31, 2020	$ 58,716	$ 41	279,905	(221,230)
BALANCE, Shares at Dec. 31, 2020	41,232,804	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	51,645,718	51,646,000