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, Common [Member]	AOCI Attributable to Parent [Member]	Total
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
Stock issued for the exercise of stock options and stock appreciation rights				18			18
Stock issued for the exercise of stock options and stock appreciation rights, shares			10,294
Stock-based compensation				2,514			2,514
Share-based compensation, shares			10,699
Components of net loss						(4,086)	(4,086)
Employee stock purchase plan				36			36
Employee stock purchase plan, shares			6,071
Preferred stock conversion							0
Preferred stock conversion, shares	(1)		2,025
Ending balance, value at Mar. 31, 2022	$ 5,584	$ 6	$ 75	535,209	(206)	(502,762)	32,322
Ending balance, shares at Mar. 31, 2022	22,386	5,610,121	74,647,329
Beginning balance, value at Dec. 31, 2022	$ 5,583	$ 6	$ 75	543,438	(206)	(516,967)	26,346
Beginning balance, shares at Dec. 31, 2022	22,383	5,610,121	74,874,459
Stock-based compensation				2,655			2,655
Share-based compensation, shares			144,054
Components of net loss						(5,347)	(5,347)
Employee stock purchase plan				23			23
Employee stock purchase plan, shares			11,798
Stock issued for the exercise of stock options				33			$ 33
Stock issued for the exercise of stock options, shares			29,188				29,188
Ending balance, value at Mar. 31, 2023	$ 5,583	$ 6	$ 75	$ 546,149	$ (206)	$ (522,314)	$ 23,710
Ending balance, shares at Mar. 31, 2023	22,383	5,610,121	75,059,499