Note 2 - Revenue; Accounts and Unbilled Receivables (Details Textual)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Customer Contracts, Notice of Termination Period (Day)	60 days
Customer Concentration Risk [Member] | Revenue Benchmark [Member]
Number of Major Customers	3	3
Customer Concentration Risk [Member] | Revenue Benchmark [Member] | Three Customers [Member]
Concentration Risk, Percentage	66.00%	59.00%
Customer Concentration Risk [Member] | Accounts and Unbilled Receivables [Member]
Number of Major Customers	3	4
Customer Concentration Risk [Member] | Accounts and Unbilled Receivables [Member] | Three Non-CSB Customers [Member]
Concentration Risk, Percentage	59.00%
Customer Concentration Risk [Member] | Accounts and Unbilled Receivables [Member] | Four Non-CSB Customers [Member]
Concentration Risk, Percentage		67.00%
Customer Concentration Risk [Member] | Accounts and Unbilled Receivables [Member] | Twelve CSB Customers [Member]
Concentration Risk, Percentage	89.00%	97.00%
Customer Concentration Risk [Member] | Accounts and Unbilled Receivables [Member] | CSB Customers [Member]
Number of Major Customers	12	12