Note 5 - Sales Concentrations (Details Textual) - Customer Concentration Risk [Member]	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Sales Revenue, Net [Member]
Number of Major Customers			4	2
Sales Revenue, Net [Member] | Five Major Customers [Member]
Concentration Risk, Percentage	80.00%		66.00%
Sales Revenue, Net [Member] | Two Major Customers [Member]
Concentration Risk, Percentage		59.00%		55.00%
Accounts Receivable [Member]
Number of Major Customers			1
Accounts Receivable [Member] | One Major Customer [Member]
Concentration Risk, Percentage			58.00%
Accounts Receivable [Member] | Two Major Customers [Member]
Concentration Risk, Percentage				0.00%