Note 2 - Summary of Significant Accounting Policies (Details Textual) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	May 31, 2018
Inventory Write-down	$ 171	$ 107
Contingent Liability, Repayment of State and Local Grant Funds Received	463		$ 463
City of Rochester and State of New York [Member]
Covenant, Future Amount Receivable	$ 87			$ 550