Restructuring - Recognized Cost Restructuring Activities (Details) - Restructuring 2017 - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2018
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, incurred cost	$ 2,913	$ 8,157
Restructuring charges, cash	2,300	5,200
Restructuring charges, non-cash	600	3,000
Operating expenses
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, incurred cost	1,373	4,828
Restructuring and related charges
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, incurred cost	1,540	3,329
Infrastructure Solutions
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, incurred cost	2,554	6,087
Infrastructure Solutions | Operating expenses
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, incurred cost	1,210	3,310
Infrastructure Solutions | Restructuring and related charges
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, incurred cost	1,344	2,777
Corrosion Protection
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, incurred cost	359	2,070
Corrosion Protection | Operating expenses
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, incurred cost	163	1,518
Corrosion Protection | Restructuring and related charges
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, incurred cost	$ 196	$ 552