Acquisition - Business Acquisition Purchase Price Allocation Assets Acquired and Liabilities Assumed (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
Mar. 31, 2015	Dec. 31, 2014
Business Acquisition [Line Items]
Value of Quanta common stock and exchangeable shares issued		$ 134,500
Cash paid or payable	36,900	284,300
Goodwill	1,922,485us-gaap_Goodwill	1,931,485us-gaap_Goodwill
All Acquisitions [Member]
Business Acquisition [Line Items]
Value of Quanta common stock and exchangeable shares issued		134,538
Cash paid or payable	36,868	284,312
Fair value of total consideration transferred	36,868	418,850
Current assets	12,600	172,298
Property and equipment	15,649	159,186
Other assets		3,500
Identifiable intangible assets	9,068	96,302
Current liabilities	(9,819)	(144,252)
Deferred tax liabilities, net	(4,052)	(37,743)
Other long-term liabilities	(4,909)	(4,926)
Total identifiable net assets	18,537	244,365
Goodwill	18,331	174,485
Fair value of total consideration transferred	$ 36,868	$ 418,850

Aggregate business acquisition consideration of acquired entity cash paid and liabilities incurred during period.

No definition available.

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Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

+ References

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-Publisher FASB

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Amount of equity interests of the acquirer, including instruments or interests issued or issuable in consideration for the business combination.

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Amount of assets that are expected to be realized or consumed within one year or the normal operating cycle, if longer, acquired at the acquisition date.

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Amount of liabilities due within one year or within the normal operating cycle, if longer, assumed at the acquisition date.

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Amount of deferred tax liability attributable to taxable temporary differences due after one year or the normal operating cycle, if longer, assumed at the acquisition date.

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- Definition

Amount of assets, excluding financial assets and goodwill, that lack physical substance, having a projected indefinite period of benefit, acquired at the acquisition date.

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Amount of intangible assets, excluding goodwill, acquired at the acquisition date.

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Amount of other liabilities due after one year or the normal operating cycle, if longer, assumed at the acquisition date.

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Amount of other assets expected to be realized or consumed after one year or the normal operating cycle, if longer, acquired at the acquisition date.

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The amount of property, plant, and equipment recognized as of the acquisition date.

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Amount recognized for assets, including goodwill, in excess of (less than) the aggregate liabilities assumed.

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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.

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