Note 2 - Concentration of Credit Risk and Major Customers (Details Textual) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2020 USD ($)	Jun. 30, 2019	Jun. 30, 2020 USD ($)	Jun. 30, 2019	Dec. 31, 2019
Excess Cash Balances, Number of High Credit Quality Financial Institutions			2
Cash, Ending Balance	$ 754		$ 754
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%	21.00%	22.00%	22.00%
Customer Concentration Risk [Member] | Revenue Benchmark [Member] | Division Two of Largest Customer [Member]
Concentration Risk, Percentage	3.00%	2.00%	2.00%	2.00%
Customer Concentration Risk [Member] | Revenue Benchmark [Member] | Largest Customer [Member]
Concentration Risk, Percentage	23.00%	23.00%	24.00%	24.00%
Customer Concentration Risk [Member] | Accounts Receivable [Member] | Largest Customer [Member]
Concentration Risk, Percentage			40.00%		36.00%
Geographic Concentration Risk [Member] | Revenue Benchmark [Member] | Largest Customer [Member]
Concentration Risk, Percentage	9.00%	17.00%	11.00%	18.00%
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	$ 318		$ 318