Restructuring - Restructuring Reserve by Type of Cost (Details) - Restructuring Plan 2016 - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Restructuring Cost and Reserve [Line Items]
Non-Cash Restructuring Charges	$ 508		$ 508
Cash Restructuring Charges	3,255		12,997
Pre-tax charges (reversals) related to restructuring	3,763		13,505
Cost of revenues
Restructuring Cost and Reserve [Line Items]
Non-Cash Restructuring Charges	0		0
Cash Restructuring Charges	10		59
Pre-tax charges (reversals) related to restructuring	10		59
Operating expenses
Restructuring Cost and Reserve [Line Items]
Non-Cash Restructuring Charges	259		259
Cash Restructuring Charges	1,710		4,673
Pre-tax charges (reversals) related to restructuring	1,969		4,932
Restructuring charges
Restructuring Cost and Reserve [Line Items]
Non-Cash Restructuring Charges	0		0
Cash Restructuring Charges	1,535		8,265
Pre-tax charges (reversals) related to restructuring	1,535		8,265
Other Expense [Member]
Restructuring Cost and Reserve [Line Items]
Non-Cash Restructuring Charges	249		249
Cash Restructuring Charges	0		0
Pre-tax charges (reversals) related to restructuring	249		$ 249
Infrastructure Solutions | Operating expenses
Restructuring Cost and Reserve [Line Items]
Pre-tax charges (reversals) related to restructuring	400	$ 600
Infrastructure Solutions | Restructuring charges
Restructuring Cost and Reserve [Line Items]
Pre-tax charges (reversals) related to restructuring	600	2,500
Corrosion Protection | Operating expenses
Restructuring Cost and Reserve [Line Items]
Pre-tax charges (reversals) related to restructuring	100	400
Corrosion Protection | Restructuring charges
Restructuring Cost and Reserve [Line Items]
Pre-tax charges (reversals) related to restructuring	800	3,200
Energy Services | Operating expenses
Restructuring Cost and Reserve [Line Items]
Pre-tax charges (reversals) related to restructuring	1,500	3,900
Energy Services | Restructuring charges
Restructuring Cost and Reserve [Line Items]
Pre-tax charges (reversals) related to restructuring	$ 100	$ 2,500