Note 2 - Concentration of Credit Risk and Major Customers (Details Textual)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Excess Cash Balances, Number of High Credit Quality Financial Institutions	2
Concentration Risk, Number of Divisions	2	2
Geographic Concentration Risk [Member] | Revenue Benchmark [Member] | Division One of Largest Customer [Member]
Concentration Risk, Percentage	19.90%	20.80%
Geographic Concentration Risk [Member] | Revenue Benchmark [Member] | Division Two of Largest Customer [Member]
Concentration Risk, Percentage	2.60%	2.40%
Geographic Concentration Risk [Member] | Revenue Benchmark [Member] | Largest Customer [Member]
Concentration Risk, Percentage	22.50%	23.20%
Geographic Concentration Risk [Member] | Accounts Receivable [Member] | Largest Customer [Member]
Concentration Risk, Percentage	35.60%	16.30%