Note 2 - Concentration of Credit Risk and Major Customers (Details Textual) $ in Thousands	3 Months Ended		6 Months Ended	9 Months Ended		12 Months Ended
	Sep. 30, 2020 USD ($)	Sep. 30, 2019	Jun. 30, 2019	Sep. 30, 2020 USD ($)	Sep. 30, 2019	Dec. 31, 2019
Excess Cash Balances, Number of High Credit Quality Financial Institutions				2
Cash, Ending Balance	$ 1,694			$ 1,694
Concentration Risk, Number of Divisions			2	2
Customer Concentration Risk [Member] | Revenue Benchmark [Member] | Division One of Largest Customer [Member]
Concentration Risk, Percentage	20.00%	19.00%		21.00%	21.00%
Customer Concentration Risk [Member] | Revenue Benchmark [Member] | Division Two of Largest Customer [Member]
Concentration Risk, Percentage	3.00%	3.00%		3.00%	3.00%
Customer Concentration Risk [Member] | Revenue Benchmark [Member] | Largest Customer [Member]
Concentration Risk, Percentage	23.00%	22.00%		24.00%	24.00%
Customer Concentration Risk [Member] | Accounts Receivable [Member] | Largest Customer [Member]
Concentration Risk, Percentage				37.00%		36.00%
Geographic Concentration Risk [Member] | Revenue Benchmark [Member] | Largest Customer [Member]
Concentration Risk, Percentage	9.00%	9.00%		10.00%	15.00%
UNITED STATES
Excess Cash Balances, Number of High Credit Quality Financial Institutions				1
CHINA
Excess Cash Balances, Number of High Credit Quality Financial Institutions				1
Cash, Ending Balance	$ 244			$ 244