Note 2 - Summary of Significant Accounting Policies (Details Textual) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Dec. 31, 2018	May 31, 2018
Contingent Liability, Repayment of State and Local Grant Funds Received	$ 463	$ 200
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%
City of Rochester and State of New York [Member]
Covenant, Future Amount Receivable	$ 87		$ 550
Thermal Products and Mechanical Products [Member]
Equipment Leased To Customers Initial Term	180 days