Note 3 - Revenues 1 (Details Textual) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Disposal Group, Including Discontinued Operation, Contract Assets, Current	$ 0.9		$ 0.9		$ 5.4
Disposal Group, Including Discontinued Operation, Contract Liabilities, Current	0.1		0.1		0.1
Contract with Customer, Liability, Total					$ 37.6	$ 32.3
Construction, Engineering and Installation Services [Member]
Revenue, Remaining Performance Obligation, Amount	$ 491.0		$ 491.0
Product and Services [Member]
Revenue Recognized, Percent	89.20%	92.60%	90.10%	92.40%
Product [Member]
Revenue Recognized, Percent	10.80%	7.40%	9.90%	7.60%