Note 8 - Major Customers and Accounts Receivable (Details Textual) - Customer Concentration Risk [Member]	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Revenue Benchmark [Member] | Customer 1 [Member]
Concentration Risk, Percentage	22.00%	27.00%	28.00%	29.00%
Revenue Benchmark [Member] | Customer 2 [Member]
Concentration Risk, Percentage	20.00%	13.00%	12.00%	13.00%
Revenue Benchmark [Member] | Customer 3 [Member]
Concentration Risk, Percentage	10.00%	2.00%	12.00%	0.00%
Accounts Receivable [Member] | Two Customers [Member]
Concentration Risk, Percentage			59.00%		53.00%