Restructuring - Pre Tax Restructuring Cost (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 1,219	$ 5,439	$ 4,548	$ 5,439
Restructuring 2017
Restructuring Cost and Reserve [Line Items]
Restructuring charges	7,423	6,737	15,580	6,737
Severance and benefit related costs | Restructuring 2017
Restructuring Cost and Reserve [Line Items]
Restructuring charges	949	5,070	3,217	5,070
Lease and contract termination costs | Restructuring 2017
Restructuring Cost and Reserve [Line Items]
Restructuring charges	215	340	1,202	340
Relocation and other moving costs | Restructuring 2017
Restructuring Cost and Reserve [Line Items]
Restructuring charges	55	29	129	29
Other restructuring | Restructuring 2017
Restructuring Cost and Reserve [Line Items]
Restructuring charges	6,204	1,298	11,032	1,298
Infrastructure Solutions | Restructuring 2017
Restructuring Cost and Reserve [Line Items]
Restructuring charges	6,269	4,573	12,356	4,573
Infrastructure Solutions | Severance and benefit related costs | Restructuring 2017
Restructuring Cost and Reserve [Line Items]
Restructuring charges	914	3,140	2,780	3,140
Infrastructure Solutions | Lease and contract termination costs | Restructuring 2017
Restructuring Cost and Reserve [Line Items]
Restructuring charges	215	250	1,052	250
Infrastructure Solutions | Relocation and other moving costs | Restructuring 2017
Restructuring Cost and Reserve [Line Items]
Restructuring charges	55	0	129	0
Infrastructure Solutions | Other restructuring | Restructuring 2017
Restructuring Cost and Reserve [Line Items]
Restructuring charges	5,085	1,183	8,395	1,183
Corrosion Protection | Restructuring 2017
Restructuring Cost and Reserve [Line Items]
Restructuring charges	1,154	2,164	3,224	2,164
Corrosion Protection | Severance and benefit related costs | Restructuring 2017
Restructuring Cost and Reserve [Line Items]
Restructuring charges	35	1,930	437	1,930
Corrosion Protection | Lease and contract termination costs | Restructuring 2017
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0	90	150	90
Corrosion Protection | Relocation and other moving costs | Restructuring 2017
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0	29	0	29
Corrosion Protection | Other restructuring | Restructuring 2017
Restructuring Cost and Reserve [Line Items]
Restructuring charges	1,119	115	2,637	115
Corporate, Non-Segment | Restructuring 2017
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 300	$ 800	$ 900	$ 800