Note 1 - Organization and Summary of Significant Accounting Policies (Details Textual) $ / shares in Units, $ in Thousands	3 Months Ended			6 Months Ended	9 Months Ended		12 Months Ended
	Sep. 30, 2021 USD ($) $ / shares	Jun. 30, 2021 USD ($) $ / shares	Sep. 30, 2020 USD ($)	Jun. 30, 2021 USD ($) $ / shares	Sep. 30, 2021 USD ($) $ / shares shares	Sep. 30, 2020 USD ($)	Dec. 31, 2020 USD ($) $ / shares
Common Stock, Par or Stated Value Per Share (in dollars per share) | $ / shares	$ 0.0001	$ 0.0001		$ 0.0001	$ 0.0001		$ 0.0001
Number of Wholly-owned Subsidiaries	1				1
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount (in shares) | shares					5,397,165
Product Line Exit Expense	$ 0	$ 747	$ 0		$ 747	$ 0	$ 0
Write-off, Inventory Cost	54	531
Retiring Cost				$ 106
Raw Material Purchase Reserve		$ 110		$ 110
Inventory Valuation Reserves, Ending Balance	$ 56				$ 56		$ (0)