Note 7 - Goodwill and Intangible Assets - Reconciliation Goodwill (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2020	Dec. 31, 2019
Goodwill, gross	$ 396,984	$ 398,610
Accumulated impairment losses	(141,775)	(141,775)
Goodwill, net	255,209	256,835
Foreign currency translation	(1,626)
Infrastructure Solutions [Member]
Goodwill, gross	239,276	240,160
Accumulated impairment losses	(62,848)	(62,848)
Goodwill, net	176,428	177,312
Foreign currency translation	(884)
Corrosion Protection [Member]
Goodwill, gross	76,204	76,946
Accumulated impairment losses	(45,400)	(45,400)
Goodwill, net	30,804	31,546
Foreign currency translation	(742)
Energy Services [Member]
Goodwill, gross	81,504	81,504
Accumulated impairment losses	(33,527)	(33,527)
Goodwill, net	47,977	$ 47,977
Foreign currency translation	$ 0

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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-Publisher FASB
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