Note 2 - Concentration of Credit Risk and Major Customers (Details Textual) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2022 USD ($)	Mar. 31, 2021	Dec. 31, 2021
Excess Cash Balances, Number of High Credit Quality Financial Institutions	2
Customer Concentration Risk [Member] | Revenue from Contract with Customer Benchmark [Member] | One Customer [Member]
Concentration Risk, Percentage	23.00%	29.00%
Concentration Risk Number of Customers	1	1
Customer Concentration Risk [Member] | Revenue from Contract with Customer Benchmark [Member] | Largest Customer [Member]
Concentration Risk, Percentage	5.00%	4.00%
Customer Concentration Risk [Member] | Accounts Receivable [Member] | Two Customers [Member]
Concentration Risk, Percentage	35.00%		19.00%
Concentration Risk Number of Customers	2		1
UNITED STATES
Excess Cash Balances, Number of High Credit Quality Financial Institutions	1,000
Cash	$ 1,617
CHINA
Excess Cash Balances, Number of High Credit Quality Financial Institutions	1
Cash	$ 769
MEXICO
Cash	$ 63