Note 3 - Revenues 1 (Details Textual) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Disposal Group, Including Discontinued Operation, Contract Assets, Current	$ 0.7		$ 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	$ 501.8
Product and Services [Member]
Revenue Recognized, Percent	90.60%	92.30%
Product [Member]
Revenue Recognized, Percent	9.40%	7.70%