Goodwill and Other Intangible Assets - Summary of Changes in Quanta's Goodwill (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015
Goodwill [Line Items]
Goodwill, beginning balance	$ 1,552,658	$ 1,596,695
Goodwill acquired	45,186	51,860
Purchase price allocation adjustments	15	(8,117)
Goodwill impaired		(39,826)
Foreign currency translation adjustments	5,310	(47,954)
Goodwill gross, ending balance	1,642,902	1,592,551
Accumulated impairment	(39,733)	(39,893)
Goodwill, ending balance	1,603,169	1,552,658
Electric Power Division [Member]
Goodwill [Line Items]
Goodwill, beginning balance	1,226,245	1,223,224
Goodwill acquired	24,168	31,224
Purchase price allocation adjustments	229	750
Foreign currency translation adjustments	3,337	(28,953)
Goodwill gross, ending balance	1,253,979	1,226,245
Goodwill, ending balance	1,253,979	1,226,245
Oil and Gas Infrastructure Division [Member]
Goodwill [Line Items]
Goodwill, beginning balance	326,413	373,471
Goodwill acquired	21,018	20,636
Purchase price allocation adjustments	(214)	(8,867)
Goodwill impaired		(39,826)
Foreign currency translation adjustments	1,973	(19,001)
Goodwill gross, ending balance	388,923	366,306
Accumulated impairment	(39,733)	(39,893)
Goodwill, ending balance	$ 349,190	$ 326,413

Amount of write-down of goodwill from impairment recognized.

No definition available.

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Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
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-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

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-Publisher FASB
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Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination.

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Amount of foreign currency translation gain (loss) which increases (decreases) an asset representing future economic benefits from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount before accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount of accumulated impairment loss for an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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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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Amount of increase (decrease) from adjustments after acquisition date under purchase accounting of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 25
-Paragraph 16
-URI http://asc.fasb.org/extlink&oid=73531572&loc=d3e961-128460

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