Note 3 - Revenues 1 (Details Textual) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Disposal Group, Including Discontinued Operation, Contract Assets, Current	$ 1.8		$ 5.4
Disposal Group, Including Discontinued Operation, Contract Liabilities, Current	0.1		0.1
Contract with Customer, Liability, Total	37.6		$ 32.3
Construction, Engineering and Installation Services [Member]
Revenue, Remaining Performance Obligation, Amount	$ 462.3
Product and Services [Member]
Revenue Recognized, Percent	90.80%	92.90%
Product [Member]
Revenue Recognized, Percent	9.20%		7.10%