Note 4 - Revenue; Accounts and Unbilled Receivables (Details Textual) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Customer Contracts, Notice of Termination Period	60 days
Accounts Receivable, Allowance for Credit Loss, Ending Balance	$ 0	$ 0
Customer Concentration Risk [Member] | Revenue Benchmark [Member]
Number of Major Customers	4	2
Customer Concentration Risk [Member] | Revenue Benchmark [Member] | Two Customers [Member]
Concentration Risk, Percentage	63.10%	44.60%
Customer Concentration Risk [Member] | Accounts and Unbilled Receivables [Member] | Four Non-CSB Customers [Member]
Concentration Risk, Percentage	61.60%	60.90%
Number of Major Customers	4	4
Customer Concentration Risk [Member] | Accounts and Unbilled Receivables [Member] | Fourteen CSB Customers [Member]
Concentration Risk, Percentage	96.60%	95.30%
Number of Major Customers	14	14