Segment Reporting - Financial Information by Segment (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Segment Reporting Information [Line Items]
Revenues	$ 308,524	$ 356,595	$ 900,118	$ 1,002,857
Gross profit	66,318	77,121	181,922	208,364
Operating income (loss)	20,505	24,938	24,511	48,586
Interest expense	(3,825)	(3,144)	(11,081)	(9,365)
Interest income	37	25	197	229
Other	288	(359)	(1,183)	(2,360)
Total other expense	(3,500)	(3,478)	(12,067)	(11,496)
Income before taxes on income	17,005	21,460	12,444	37,090
Restructuring charges	212	172	8,544	1,034
Acquisition-related expenses	(324)	(457)	(2,059)	(780)
Restructuring Plan 2014
Segment Reporting Information [Line Items]
Restructuring charges	(400)	1,500	(500)	10,700
Restructuring Plan 2016
Segment Reporting Information [Line Items]
Restructuring charges	1,287		14,791
Schultz Mechanical Contractors, Inc.
Segment Reporting Information [Line Items]
Restructuring charges			200
Infrastructure Solutions
Segment Reporting Information [Line Items]
Revenues	158,562	149,606	434,523	421,170
Gross profit	40,566	38,428	109,485	106,074
Operating income (loss)	18,573	16,255	37,448	35,701
Acquisition-related expenses	(300)		(2,100)
Inventory step up expense			3,600
Infrastructure Solutions \| Restructuring Plan 2014
Segment Reporting Information [Line Items]
Restructuring charges	(400)	1,400	(500)	7,900
Infrastructure Solutions \| Restructuring Plan 2016
Segment Reporting Information [Line Items]
Operating income (loss)			3,100
Restructuring charges	(31)		3,340
Corrosion Protection
Segment Reporting Information [Line Items]
Revenues	95,084	121,392	281,939	329,157
Gross profit	18,374	27,595	52,676	70,311
Operating income (loss)	513	6,886	(7,626)	8,323
Acquisition-related expenses		(500)
Corrosion Protection \| Restructuring Plan 2016
Segment Reporting Information [Line Items]
Restructuring charges	178		3,872
Energy Services
Segment Reporting Information [Line Items]
Revenues	54,878	85,597	183,656	252,530
Gross profit	7,378	11,098	19,761	31,979
Operating income (loss)	1,419	$ 1,797	(5,311)	4,562
Energy Services \| Restructuring Plan 2016
Segment Reporting Information [Line Items]
Restructuring charges	$ 1,140		$ 7,579	7,600
Energy Services \| Schultz Mechanical Contractors, Inc.
Segment Reporting Information [Line Items]
Acquisition-related expenses				$ (300)

This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities.

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This element represents the amount of any measurement period adjustment (as defined) realized during the reporting period to inventory acquired in connection with a business combination for which the initial accounting was incomplete.

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Aggregate revenue less cost of goods and services sold or operating expenses directly attributable to the revenue generation activity.

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Amount of income (loss) from continuing operations before deduction of income tax expense (benefit) and income (loss) attributable to noncontrolling interest, and addition of income (loss) from equity method investments.

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Amount of the cost of borrowed funds accounted for as interest expense.

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Amount before accretion (amortization) of purchase discount (premium) of interest income on nonoperating securities.

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The aggregate amount of income or expense from ancillary business-related activities (that is to say, excluding major activities considered part of the normal operations of the business).

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The net result for the period of deducting operating expenses from operating revenues.

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Amount of income (expense) related to nonoperating activities, classified as other.

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Amount of expenses associated with exit or disposal activities pursuant to an authorized plan. Excludes expenses related to a discontinued operation or an asset retirement obligation.

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Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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