Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]	Treasury Stock [Member]
Beginning Balance at Dec. 31, 2019	$ 5,071	$ 196	$ 230,615	$ (224,325)	$ (1,415)
Beginning Balance, shares at Dec. 31, 2019		19,546,151
Issuance of common stock relative to vesting of restricted stock, shares		23,500
Issuance of common stock pursuant to stock option plans	196	$ 1	195
Issuance of common stock pursuant to stock option plans, shares		36,799
Issuance of stock upon conversion of Debentures	21,164	$ 18	21,146
Issuance of stock upon conversion of Debentures, shares		1,819,466
Stock-based compensation	464		464
Net loss	(11,812)			(11,812)
Ending Balance at Mar. 31, 2020	15,083	$ 215	252,420	(236,137)	(1,415)
Ending Balance, shares at Mar. 31, 2020		21,425,916
Beginning Balance at Dec. 31, 2020	30,525	$ 236	273,639	(241,935)	(1,415)
Beginning Balance, shares at Dec. 31, 2020		23,694,406
Issuance of common stock relative to vesting of restricted stock, shares		20,000
Issuance of common stock, net	23,229	$ 14	23,215
Issuance of common stock, net, shares		1,393,738
Issuance of common stock pursuant to stock option plans	271	$ 1	270
Issuance of common stock pursuant to stock option plans, shares		28,934
Issuance of common stock pursuant Employee Stock Purchase Plan	47		47
Issuance of common stock pursuant Employee Stock Purchase Plan, shares		6,354
Stock-based compensation	935		935
Net loss	(1,643)			(1,643)
Ending Balance at Mar. 31, 2021	$ 53,364	$ 251	$ 298,106	$ (243,578)	$ (1,415)
Ending Balance, shares at Mar. 31, 2021		25,143,432