Note 3 - Revenues 1 (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2018
Disposal Group, Including Discontinued Operation, Contract Assets, Current	$ 5,400	$ 1,800
Disposal Group, Including Discontinued Operation, Contract Liabilities, Current	100	100
Increase (Decrease) in Contract with Customer, Liability	5,091	(24,144)	$ (5,924)
Contract with Customer, Liability, Total		$ 32,300	$ 51,600
Construction, Engineering and Installation Services [Member]
Revenue, Remaining Performance Obligation, Amount	464,600
Difference Between Work Performed On Open Contracts And Contractual Billing Terms [Member]
Increase (Decrease) in Contract with Customer, Asset	(11,400)
Increase (Decrease) in Contract with Customer, Liability	$ 5,200
Product and Services [Member]
Revenue Recognized, Percent	92.30%	93.50%	93.50%
Product [Member]
Revenue Recognized, Percent	7.70%	6.50%	6.50%
Difference between Revenue Guidance in Effect before and after Topic 606 [Member]
Contract with Customer, Liability, Cumulative Catch-up Adjustment to Revenue, Modification of Contract	$ (400)	$ 1,800
Accounting Standards Update 2014-09 [Member] | Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption				$ (300)