Goodwill and Intangible Assets - Reconciliation Goodwill (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Goodwill [Roll Forward]
Goodwill, gross - beginning balance		$ 393,615	$ 344,116
Goodwill, accumulated impairment loss - beginning balance		(94,996)	(94,996)
Goodwill, net - beginning balance		298,619	249,120
Additions to goodwill through acquisitions		3,355	50,585
Goodwill impairment		45,390	0	$ 43,484
Foreign currency translation		4,131	(1,086)
Goodwill, gross - ending balance		401,101	393,615	344,116
Goodwill, accumulated impairment loss - ending balance		(140,386)	(94,996)	(94,996)
Goodwill, net - ending balance		260,715	298,619	249,120
Underground Solutions
Goodwill [Roll Forward]
Additions to goodwill through acquisitions			44,000
Fyfe
Goodwill [Roll Forward]
Additions to goodwill through acquisitions			2,400
LMJ
Goodwill [Roll Forward]
Additions to goodwill through acquisitions			800
Concrete Solutions
Goodwill [Roll Forward]
Additions to goodwill through acquisitions			3,400
Goodwill impairment		2,200
Environmental Techniques
Goodwill [Roll Forward]
Additions to goodwill through acquisitions		3,400
Infrastructure Solutions
Goodwill [Roll Forward]
Goodwill, gross - beginning balance		239,494	190,525
Goodwill, accumulated impairment loss - beginning balance		(16,069)	(16,069)
Goodwill, net - beginning balance		223,425	174,456
Additions to goodwill through acquisitions		3,355	50,585
Goodwill impairment	$ 45,400	45,390
Foreign currency translation		3,637	(1,616)
Goodwill, gross - ending balance		246,486	239,494	190,525
Goodwill, accumulated impairment loss - ending balance		(61,459)	(16,069)	(16,069)
Goodwill, net - ending balance		185,027	223,425	174,456
Corrosion Protection
Goodwill [Roll Forward]
Goodwill, gross - beginning balance		73,875	73,345
Goodwill, accumulated impairment loss - beginning balance		(45,400)	(45,400)
Goodwill, net - beginning balance		28,475	27,945
Additions to goodwill through acquisitions		0	0
Goodwill impairment		0		10,000
Foreign currency translation		494	530
Goodwill, gross - ending balance		74,369	73,875	73,345
Goodwill, accumulated impairment loss - ending balance		(45,400)	(45,400)	(45,400)
Goodwill, net - ending balance		28,969	28,475	27,945
Energy Services
Goodwill [Roll Forward]
Goodwill, gross - beginning balance		80,246	80,246
Goodwill, accumulated impairment loss - beginning balance		(33,527)	(33,527)
Goodwill, net - beginning balance		46,719	46,719
Additions to goodwill through acquisitions		0	0
Goodwill impairment		0		33,500
Foreign currency translation		0	0
Goodwill, gross - ending balance		80,246	80,246	80,246
Goodwill, accumulated impairment loss - ending balance		(33,527)	(33,527)	(33,527)
Goodwill, net - ending balance		$ 46,719	$ 46,719	$ 46,719