Note 2 - Concentration of Credit Risk and Major Customers (Details Textual)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Excess Cash Balances, Number of High Credit Quality Financial Institutions	2
Concentration Risk, Number of Divisions	2	2
Customer Concentration Risk [Member] | Revenue Benchmark [Member]
Concentration Risk, Percentage	20.00%	20.00%
Customer Concentration Risk [Member] | Revenue Benchmark [Member] | Division One of Largest Customer [Member]
Concentration Risk, Percentage	21.20%	19.90%
Customer Concentration Risk [Member] | Revenue Benchmark [Member] | Division Two of Largest Customer [Member]
Concentration Risk, Percentage	2.20%	2.60%
Customer Concentration Risk [Member] | Revenue Benchmark [Member] | Largest Customer [Member]
Concentration Risk, Percentage	23.40%	22.50%
Customer Concentration Risk [Member] | Accounts Receivable [Member] | Largest Customer [Member]
Concentration Risk, Percentage	19.60%	35.60%