Note 10 - Significant Risk Concentrations - Rebate Credits (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Cost of Sales [Member]
Reductions	$ 500	$ 87	$ 654	$ 240
Selling and Marketing Expense [Member]
Reductions	$ 123	$ 597	$ 1,026	$ 1,027