Note 8 - Concentrations (Details Textual)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018
Number of Areas in Which Operations are Concentrated			1
Customer Concentration Risk [Member] | Sales Revenue, Net [Member] | U.S. Government [Member]
Concentration Risk, Percentage	88.40%	72.20%
Customer Concentration Risk [Member] | Sales Revenue, Net [Member] | Four Government Customers [Member]
Concentration Risk, Percentage	73.70%
Number of Major Customers	4
Customer Concentration Risk [Member] | Sales Revenue, Net [Member] | Three Government Customers [Member]
Concentration Risk, Percentage		54.20%
Number of Major Customers		3
Customer Concentration Risk [Member] | Sales Revenue, Net [Member] | One Commercial Customer [Member]
Concentration Risk, Percentage	10.20%	25.90%
Number of Major Customers	1	1