Etratech Acquisition - Schedule of Intangible Assets (Detail) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2018	Dec. 31, 2017
Finite And Indefinite Lived Intangible Assets [Line Items]
Net Value	$ 60,202	$ 83,286
Etratech Inc.
Finite And Indefinite Lived Intangible Assets [Line Items]
Gross Value	32,898
Accumulated Amortization	3,410
Net Value	29,488
Etratech Inc. \| Customer relationships
Finite And Indefinite Lived Intangible Assets [Line Items]
Gross Value	24,424
Accumulated Amortization	1,909
Net Value	$ 22,515
Etratech Inc. \| Customer relationships \| Minimum
Finite And Indefinite Lived Intangible Assets [Line Items]
Useful Life	8 years
Etratech Inc. \| Customer relationships \| Maximum
Finite And Indefinite Lived Intangible Assets [Line Items]
Useful Life	12 years
Etratech Inc. \| Technology
Finite And Indefinite Lived Intangible Assets [Line Items]
Gross Value	$ 8,474
Accumulated Amortization	1,501
Net Value	$ 6,973
Etratech Inc. \| Technology \| Minimum
Finite And Indefinite Lived Intangible Assets [Line Items]
Useful Life	5 years
Etratech Inc. \| Technology \| Maximum
Finite And Indefinite Lived Intangible Assets [Line Items]
Useful Life	6 years

Finite and indefinite lived intangible assets.

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Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

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Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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-Topic 350
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- Definition

Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 928
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-Section 50
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Amount after amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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