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]	Retained Earnings [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-based compensation				7,906			7,906
Stock-based compensation, shares			110,726
Components of net loss						(14,138)	(14,138)
Employee stock purchase plan				92			92
Employee stock purchase plan, shares			29,327
Stock issued for the exercise of stock options				67			67
Stock issued for the exercise of stock options, shares			71,960
Preferred stock conversion
Preferred stock conversion, shares	(1)		2,025
Ending balance, value at Sep. 30, 2022	$ 5,584	$ 6	$ 75	540,706	(206)	(512,814)	27,767
Ending balance, shares at Sep. 30, 2022	22,386	5,610,121	74,832,278
Beginning balance, value at Jun. 30, 2022	$ 5,584	$ 6	$ 75	537,963	(206)	(507,897)	29,941
Beginning balance, shares at Jun. 30, 2022	22,386	5,610,121	74,686,056
Stock issued for the exercise of stock options				22			22
Stock issued for the exercise of stock options, shares			31,437
Stock-based compensation				2,695			2,695
Stock-based compensation, shares			100,027
Components of net loss						(4,917)	(4,917)
Employee stock purchase plan				26			26
Employee stock purchase plan, shares			14,758
Ending balance, value at Sep. 30, 2022	$ 5,584	$ 6	$ 75	540,706	(206)	(512,814)	27,767
Ending balance, shares at Sep. 30, 2022	22,386	5,610,121	74,832,278
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				7,987			7,987
Stock-based compensation, shares			316,646
Components of net loss						(15,673)	(15,673)
Employee stock purchase plan				73			73
Employee stock purchase plan, shares			41,685
Stock issued for the exercise of stock options				(18)			$ (18)
Stock issued for the exercise of stock options, shares			30,384				30,188
Preferred stock conversion		$ (6)	$ 6
Preferred stock conversion, shares		(5,610,121)	5,610,121
Ending balance, value at Sep. 30, 2023	$ 5,583		$ 81	551,480	(206)	(532,640)	18,715
Ending balance, shares at Sep. 30, 2023	22,383		80,873,295
Beginning balance, value at Jun. 30, 2023	$ 5,583		$ 81	548,782	(206)	(527,271)	21,386
Beginning balance, shares at Jun. 30, 2023	22,383		80,682,586
Stock-based compensation				2,672			2,672
Stock-based compensation, shares			172,592
Components of net loss						(5,369)	(5,369)
Employee stock purchase plan				25			25
Employee stock purchase plan, shares			17,117
Stock issued for the exercise of stock options				1			1
Stock issued for the exercise of stock options, shares			1,000
Ending balance, value at Sep. 30, 2023	$ 5,583		$ 81	$ 551,480	$ (206)	$ (532,640)	$ 18,715
Ending balance, shares at Sep. 30, 2023	22,383		80,873,295