Statements of Stockholders' Equity (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Total
Beginning balance, value at Dec. 31, 2020	$ 22	$ 187,463	$ (150,140)	$ 37,345
Beginning balance, shares at Dec. 31, 2020	22,375
Stock-based compensation		731		731
Stock-based compensation, shares	71
At-the-market sale of stock, net of commissions and expenses		243		243
At-the-market sale of stock, net of commissions and expenses, shares	14
Stock option exercise	$ 1	2,514		2,515
Stock option exercise, shares	398
Warrant Exercise
Warrant Exercise, shares	223
Forfeited restricted stock awards
Forfeited restricted stock awards, shares	(54)
Net loss			(3,620)	(3,620)
Ending balance, value at Mar. 31, 2021	$ 23	190,951	(153,760)	37,214
Ending balance, shares at Mar. 31, 2021	23,027
Stock-based compensation		847		847
Stock-based compensation, shares	18
Stock option exercise		354		354
Stock option exercise, shares	59
Net loss			(3,726)	(3,726)
Ending balance, value at Jun. 30, 2021	$ 23	192,152	(157,486)	34,689
Ending balance, shares at Jun. 30, 2021	23,104
Beginning balance, value at Dec. 31, 2021	$ 23	194,212	(165,854)	28,381
Beginning balance, shares at Dec. 31, 2021	23,207
Stock-based compensation		726		726
Stock-based compensation, shares	161
Stock option exercise		166		166
Stock option exercise, shares	25
Net loss			(4,086)	(4,086)
Ending balance, value at Mar. 31, 2022	$ 23	195,104	(169,940)	25,187
Ending balance, shares at Mar. 31, 2022	23,393
Beginning balance, value at Dec. 31, 2021	$ 23	194,212	(165,854)	28,381
Beginning balance, shares at Dec. 31, 2021	23,207
Ending balance, value at Jun. 30, 2022	$ 23	196,148	(174,421)	21,750
Ending balance, shares at Jun. 30, 2022	23,457
Beginning balance, value at Mar. 31, 2022	$ 23	195,104	(169,940)	25,187
Beginning balance, shares at Mar. 31, 2022	23,393
Stock-based compensation		859		859
Stock-based compensation, shares	33
At-the-market sale of stock, net of commissions and expenses		185		185
At-the-market sale of stock, net of commissions and expenses, shares	31
Net loss			(4,481)	(4,481)
Ending balance, value at Jun. 30, 2022	$ 23	$ 196,148	$ (174,421)	$ 21,750
Ending balance, shares at Jun. 30, 2022	23,457