Note 2 - Concentration of Credit Risk and Major Customers (Details Textual) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2020 USD ($)	Mar. 31, 2019	Dec. 31, 2019
Excess Cash Balances, Number of High Credit Quality Financial Institutions	2
Cash, Ending Balance	$ 974
Concentration Risk, Number of Divisions	2	2
Customer Concentration Risk [Member] | Revenue Benchmark [Member] | Division One of Largest Customer [Member]
Concentration Risk, Percentage	24.00%	23.00%
Customer Concentration Risk [Member] | Revenue Benchmark [Member] | Division Two of Largest Customer [Member]
Concentration Risk, Percentage	2.00%	3.00%
Customer Concentration Risk [Member] | Revenue Benchmark [Member] | Largest Customer [Member]
Concentration Risk, Percentage	26.00%	26.00%
Customer Concentration Risk [Member] | Accounts Receivable [Member] | Largest Customer [Member]
Concentration Risk, Percentage	42.00%		36.00%
Geographic Concentration Risk [Member] | Revenue Benchmark [Member] | Largest Customer [Member]
Concentration Risk, Percentage	12.00%	19.00%
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	$ 703