Restructuring - 2017 Restructuring (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2017 USD ($) employee	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring charges, pre tax	$ 17,100	$ 6,700	$ 300	$ (100)	$ 1,600	$ 900	$ 3,900	$ 9,500
Restructuring and related charges									$ 12,814	$ 9,168	$ 968
Restructuring 2017
Restructuring Cost and Reserve [Line Items]
Restructuring charges, pre tax	23,700
Restructuring charges net of tax	20,600
Restructuring and related cost, expected number of positions eliminated | employee									300
Restructuring and related charges									$ 23,743
Restructuring charges, incurred									23,743
Restructuring charges, cash									13,600
Restructuring charges, non-cash									10,100
Cash									8,474
Utilized non-cash									10,080
Restructuring reserve	5,189								5,189
Restructuring 2017 | Cost of revenues
Restructuring Cost and Reserve [Line Items]
Restructuring charges, incurred									45
Restructuring 2017 | Operating expenses
Restructuring Cost and Reserve [Line Items]
Restructuring charges, incurred									10,884
Restructuring 2017 | Restructuring charges
Restructuring Cost and Reserve [Line Items]
Restructuring and related charges									12,800
Restructuring charges, incurred									12,814
Severance and benefit related costs | Restructuring 2017
Restructuring Cost and Reserve [Line Items]
Restructuring and related charges									7,345
Restructuring charges, incurred									7,345
Cash									3,481
Utilized non-cash									0
Restructuring reserve	3,864								3,864
Lease termination costs | Restructuring 2017
Restructuring Cost and Reserve [Line Items]
Restructuring and related charges									5,320
Restructuring charges, incurred									5,320
Cash									2,706
Utilized non-cash									1,964
Restructuring reserve	650								650
Relocation and other moving costs | Restructuring 2017
Restructuring Cost and Reserve [Line Items]
Restructuring and related charges									147
Restructuring charges, incurred									147
Cash									147
Utilized non-cash									0
Restructuring reserve	0								0
Other restructuring | Restructuring 2017
Restructuring Cost and Reserve [Line Items]
Restructuring and related charges									10,931
Restructuring charges, incurred									10,931
Cash									2,140
Utilized non-cash									8,116
Restructuring reserve	675								675
Infrastructure Solutions | Restructuring 2017
Restructuring Cost and Reserve [Line Items]
Restructuring and related charges									17,826
Restructuring charges, incurred									17,826
Infrastructure Solutions | Restructuring 2017 | Cost of revenues
Restructuring Cost and Reserve [Line Items]
Restructuring charges, incurred									30
Infrastructure Solutions | Restructuring 2017 | Operating expenses
Restructuring Cost and Reserve [Line Items]
Restructuring charges, incurred									8,636
Infrastructure Solutions | Restructuring 2017 | Restructuring charges
Restructuring Cost and Reserve [Line Items]
Restructuring charges, incurred									9,160
Infrastructure Solutions | Severance and benefit related costs | Restructuring 2017
Restructuring Cost and Reserve [Line Items]
Restructuring and related charges									4,587
Infrastructure Solutions | Lease termination costs | Restructuring 2017
Restructuring Cost and Reserve [Line Items]
Restructuring and related charges									4,545
Infrastructure Solutions | Relocation and other moving costs | Restructuring 2017
Restructuring Cost and Reserve [Line Items]
Restructuring and related charges									26
Infrastructure Solutions | Other restructuring | Restructuring 2017
Restructuring Cost and Reserve [Line Items]
Restructuring and related charges									8,668
Corrosion Protection | Restructuring 2017
Restructuring Cost and Reserve [Line Items]
Restructuring and related charges									5,917
Restructuring charges, incurred									5,917
Corrosion Protection | Restructuring 2017 | Cost of revenues
Restructuring Cost and Reserve [Line Items]
Restructuring charges, incurred									15
Corrosion Protection | Restructuring 2017 | Operating expenses
Restructuring Cost and Reserve [Line Items]
Restructuring charges, incurred									2,248
Corrosion Protection | Restructuring 2017 | Restructuring charges
Restructuring Cost and Reserve [Line Items]
Restructuring charges, incurred									3,654
Corrosion Protection | Severance and benefit related costs | Restructuring 2017
Restructuring Cost and Reserve [Line Items]
Restructuring and related charges									2,758
Corrosion Protection | Lease termination costs | Restructuring 2017
Restructuring Cost and Reserve [Line Items]
Restructuring and related charges									775
Corrosion Protection | Relocation and other moving costs | Restructuring 2017
Restructuring Cost and Reserve [Line Items]
Restructuring and related charges									121
Corrosion Protection | Other restructuring | Restructuring 2017
Restructuring Cost and Reserve [Line Items]
Restructuring and related charges									2,263
Corporate, Non-Segment | Restructuring 2017
Restructuring Cost and Reserve [Line Items]
Restructuring and related charges									1,300
Minimum | Restructuring 2017
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, expected cost	5,000								5,000
Maximum | Restructuring 2017
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, expected cost	$ 7,000								$ 7,000