Note 2 - Concentration of Credit Risk and Major Customers (Details Textual) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2019 USD ($)	Jun. 30, 2018	Jun. 30, 2019 USD ($)	Jun. 30, 2018	Dec. 31, 2018
Excess Cash Balances, Number of High Credit Quality Financial Institutions			2
Cash, Ending Balance	$ 399		$ 399
Concentration Risk, Number of Divisions	2	2	2	2
Geographic Concentration Risk [Member] | Revenue Benchmark [Member] | Division One of Largest Customer [Member]
Concentration Risk, Percentage	21.00%	21.00%	22.00%	20.00%
Geographic Concentration Risk [Member] | Revenue Benchmark [Member] | Largest Customer [Member]
Concentration Risk, Percentage	17.00%	21.00%	18.00%	20.00%
Customer Concentration Risk [Member] | Revenue Benchmark [Member] | Division Two of Largest Customer [Member]
Concentration Risk, Percentage	2.00%	1.00%	2.00%	1.00%
Customer Concentration Risk [Member] | Revenue Benchmark [Member] | Largest Customer [Member]
Concentration Risk, Percentage	23.00%	22.00%	24.00%	21.00%
Customer Concentration Risk [Member] | Accounts Receivable [Member] | Largest Customer [Member]
Concentration Risk, Percentage			22.00%		16.00%
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	$ 333		$ 333