Note 7 - Major Customers (Details Textual) - Customer Concentration Risk [Member] $ in Millions	12 Months Ended
	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Revenue Benchmark [Member]
Number of Major Customers	2	2
Revenue Benchmark [Member] | Customer One [Member]
Concentration Risk, Percentage	57.00%	61.00%
Revenue Benchmark [Member] | Customer Two [Member]
Concentration Risk, Percentage	19.00%	24.00%
Accounts Receivable [Member] | Two Customers [Member]
Accounts Receivable, before Allowance for Credit Loss	$ 2.6	$ 1.5