Note 2 - Summary of Significant Accounting Policies - Concentrations (Details) - customer	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Revenue Benchmark
Concentrations
Number of Major Customers	2	3
Accounts Receivable.
Concentrations
Number of Major Customers	2
Customer Concentration Risk | Revenue Benchmark
Concentrations
Number of Major Customers			2	2
Customer Concentration Risk | Revenue Benchmark | Customer A
Concentrations
Concentration Risk, Percentage	34.00%		33.00%
Customer Concentration Risk | Revenue Benchmark | Customer B
Concentrations
Concentration Risk, Percentage	12.00%		19.00%
Customer Concentration Risk | Revenue Benchmark | Total Customer Base
Concentrations
Concentration Risk, Percentage	46.00%		52.00%	56.00%
Customer Concentration Risk | Accounts Receivable.
Concentrations
Number of Major Customers			2
Customer Concentration Risk | Accounts Receivable. | Total Customer Base
Concentrations
Concentration Risk, Percentage	9.00%	73.00%	9.00%