CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]	Total
Balance at beginning at Dec. 31, 2018		$ 339	$ 98,795	$ (97,750)	$ 1,384
Balance at beginning (in shares) at Dec. 31, 2018		33,911,792
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Sale of common stock		$ 42	1,635		1,677
Sale of common stock (in shares)		4,189,000
Stock option exercises			14		14
Stock option exercises (in shares)		36,000
Stock-based compensation			242		242
Stock conversion rights			1,200		1,200
Net income (loss)				(3,006)	(3,006)
Balance at ending at Dec. 31, 2019		$ 381	101,886	(100,756)	1,511
Balance at ending (in shares) at Dec. 31, 2019		38,136,792
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Stock option exercises		$ 1	36		37
Stock option exercises (in shares)		84,500
Stock-based compensation			195		195
Net income (loss)				989	989
Balance at ending at Dec. 31, 2020		$ 382	$ 102,117	$ (99,767)	$ 2,732
Balance at ending (in shares) at Dec. 31, 2020		38,221,292