Statements of Convertible Preferred Stock and Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Convertible preferred stock series A [Member]	Convertible preferred stock series B [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	AOCI Attributable to Parent [Member]	Total
Beginning balance, value at Dec. 31, 2020	$ 5,605	$ 6	$ 74	$ 522,710	$ (206)	$ (487,960)	$ 34,624
Beginning balance, shares at Dec. 31, 2020	22,513	5,610,121	73,694,203
Issuance of common stock				340			340
Issuance of common stock, shares			244,584
Share-based compensation				4,156			4,156
Share-based compensation, shares			272,500
Components of net loss						(2,743)	(2,743)
Employee stock purchase plan				61			61
Employee stock purchase plan, shares			11,207
Preferred stock conversion	$ (27)			27			27
Preferred stock conversion, shares	(106)		206,371
Ending balance, value at Jun. 30, 2021	$ 5,578	$ 6	$ 74	527,294	(206)	(490,703)	36,465
Ending balance, shares at Jun. 30, 2021	22,407	5,610,121	74,428,865
Beginning balance, value at Mar. 31, 2021	$ 5,578	$ 6	$ 74	524,389	(206)	(489,492)	34,771
Beginning balance, shares at Mar. 31, 2021	22,408	5,610,121	74,089,659
Issuance of common stock				87			87
Issuance of common stock, shares			89,778
Share-based compensation				2,785			2,785
Share-based compensation, shares			242,250
Components of net loss						(1,211)	(1,211)
Employee stock purchase plan				33			33
Employee stock purchase plan, shares			5,204
Preferred stock conversion
Preferred stock conversion, shares	(1)		1,974
Ending balance, value at Jun. 30, 2021	$ 5,578	$ 6	$ 74	527,294	(206)	(490,703)	36,465
Ending balance, shares at Jun. 30, 2021	22,407	5,610,121	74,428,865
Beginning balance, value at Dec. 31, 2021	$ 5,584	$ 6	$ 75	532,641	(206)	(498,676)	33,840
Beginning balance, shares at Dec. 31, 2021	22,387	5,610,121	74,618,240
Issuance of common stock				45			45
Issuance of common stock, shares			40,523
Share-based compensation				5,211			5,211
Share-based compensation, shares			10,699
Components of net loss						(9,220)	(9,220)
Employee stock purchase plan				66			66
Employee stock purchase plan, shares			14,569
Preferred stock conversion
Preferred stock conversion, shares	(1)		2,025
Ending balance, value at Jun. 30, 2022	$ 5,584	$ 6	$ 75	537,963	(206)	(507,896)	29,942
Ending balance, shares at Jun. 30, 2022	22,386	5,610,121	74,686,056
Beginning balance, value at Mar. 31, 2022	$ 5,584	$ 6	$ 75	535,209	(206)	(502,762)	32,322
Beginning balance, shares at Mar. 31, 2022	22,386	5,610,121	74,647,329
Issuance of common stock				26			26
Issuance of common stock, shares			30,229
Share-based compensation				2,698			2,698
Components of net loss						(5,134)	(5,134)
Employee stock purchase plan				30			30
Employee stock purchase plan, shares			8,498
Preferred stock conversion
Ending balance, value at Jun. 30, 2022	$ 5,584	$ 6	$ 75	$ 537,963	$ (206)	$ (507,896)	$ 29,942
Ending balance, shares at Jun. 30, 2022	22,386	5,610,121	74,686,056