Note 12 - Supplemental Cash Flow Information - Supplemental Cash Flow (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Interest paid	$ 20	$ 19
Federal, state, and local income taxes paid, net	4	0
Change in contract receivables, net	2,999	2,195
Change in contract liabilities, net	(2,655)	(2,195)
Property, plant, and equipment purchases in accounts payable	$ 1,668	$ 1,308