Goodwill and Intangible Assets - Goodwill (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Goodwill [Roll Forward]
Goodwill, gross	$ 402,535	$ 402,408
Accumulated impairment losses	(141,775)	(141,775)
Goodwill, beginning balance	260,633
Foreign currency translation	127
Goodwill, ending balance	260,760
Infrastructure Solutions
Goodwill [Roll Forward]
Goodwill, gross	244,506	244,521
Accumulated impairment losses	(62,848)	(62,848)
Goodwill, beginning balance	181,673
Foreign currency translation	(15)
Goodwill, ending balance	181,658
Corrosion Protection
Goodwill [Roll Forward]
Goodwill, gross	76,525	76,383
Accumulated impairment losses	(45,400)	(45,400)
Goodwill, beginning balance	30,983
Foreign currency translation	142
Goodwill, ending balance	31,125
Energy Services
Goodwill [Roll Forward]
Goodwill, gross	81,504	81,504
Accumulated impairment losses	(33,527)	$ (33,527)
Goodwill, beginning balance	47,977
Foreign currency translation	0
Goodwill, ending balance	$ 47,977