Note 7 - Concentrations (Details Textual)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Number of Areas in Which Operations are Concentrated	1
Customer Concentration Risk [Member] | Revenue Benchmark [Member] | U.S. Government [Member]
Concentration Risk, Percentage	86.40%	79.60%
Customer Concentration Risk [Member] | Revenue Benchmark [Member] | Three Government Customers [Member]
Concentration Risk, Percentage	64.20%
Number of Major Customers	3
Customer Concentration Risk [Member] | Revenue Benchmark [Member] | One Commercial Customer [Member]
Concentration Risk, Percentage	11.10%	19.00%
Number of Major Customers	1	1
Customer Concentration Risk [Member] | Accounts Receivable [Member] | Four Government Customers [Member]
Concentration Risk, Percentage		66.30%
Number of Major Customers		4