Note 3 - Concentrations (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accounts Receivable, Allowance for Credit Loss, Ending Balance	$ 1,152	$ 1,152
Allowance for Distributors' Price Adjustment	$ 656	$ 1,634
Customer Concentration Risk [Member] | Revenue from Contract with Customer Benchmark [Member] | Customer A and F [Member]
Concentration Risk, Percentage	14.00%	18.00%	17.00%
Customer Concentration Risk [Member] | Revenue from Contract with Customer Benchmark [Member] | Customer B and G [Member]
Concentration Risk, Percentage	11.00%	14.00%	14.00%
Customer Concentration Risk [Member] | Revenue from Contract with Customer Benchmark [Member] | Customer H [Member]
Concentration Risk, Percentage		11.00%	11.00%