Quarterly report pursuant to Section 13 or 15(d)

Acquisitions - Additional Information (Detail)

v2.4.1.9
Acquisitions - Additional Information (Detail) (USD $)
3 Months Ended 12 Months Ended
Mar. 31, 2015
Entity
Mar. 31, 2014
Dec. 31, 2014
Entity
Business Acquisition [Line Items]      
Cash paid for acquisitions $ 36,900,000pwr_AggregateBusinessAcquisitionConsiderationOfAcquiredEntityCashPaidAndLiabilitiesIncurred   $ 284,300,000pwr_AggregateBusinessAcquisitionConsiderationOfAcquiredEntityCashPaidAndLiabilitiesIncurred
Number of business acquisitions 3us-gaap_NumberOfBusinessesAcquired   9us-gaap_NumberOfBusinessesAcquired
Number of shares granted for acquired companies     686,382us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued
Value of equity interests transferred     134,500,000us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable
Goodwill acquired 18,331,000us-gaap_GoodwillAcquiredDuringPeriod    
Fair value of accounts receivable acquired 6,200,000us-gaap_BusinessCombinationAcquiredReceivablesFairValue   117,000,000us-gaap_BusinessCombinationAcquiredReceivablesFairValue
Goodwill expected to be deductible for income tax 0us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount   30,100,000us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount
Income (loss) from continuing operations before income taxes 92,560,000us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest 91,701,000us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest  
Third and Fourth Quarter 2014 [Member]      
Business Acquisition [Line Items]      
Net tangible assets acquired     106,900,000pwr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNetTangibleAssets
/ us-gaap_BusinessAcquisitionAxis
= pwr_ThirdAndFourthQuarterTwoThousandFourteenAcquisitionsMember
Goodwill acquired     116,100,000us-gaap_GoodwillAcquiredDuringPeriod
/ us-gaap_BusinessAcquisitionAxis
= pwr_ThirdAndFourthQuarterTwoThousandFourteenAcquisitionsMember
Other intangible assets, acquired     73,900,000us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill
/ us-gaap_BusinessAcquisitionAxis
= pwr_ThirdAndFourthQuarterTwoThousandFourteenAcquisitionsMember
Contributed by Acquisitions [Member]      
Business Acquisition [Line Items]      
Revenues 7,000,000us-gaap_Revenues
/ us-gaap_BusinessAcquisitionAxis
= pwr_ContributedByAcquisitionsMember
   
Income (loss) from continuing operations before income taxes (1,000,000)us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest
/ us-gaap_BusinessAcquisitionAxis
= pwr_ContributedByAcquisitionsMember
   
Acquisition costs 500,000us-gaap_AcquisitionCosts
/ us-gaap_BusinessAcquisitionAxis
= pwr_ContributedByAcquisitionsMember
   
First Quarter Two Thousand Fifteen [Member]      
Business Acquisition [Line Items]      
Net tangible assets acquired 9,500,000pwr_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNetTangibleAssets
/ us-gaap_BusinessAcquisitionAxis
= pwr_FirstQuarterTwoThousandFifteenAcquisitionsMember
   
Goodwill acquired 18,300,000us-gaap_GoodwillAcquiredDuringPeriod
/ us-gaap_BusinessAcquisitionAxis
= pwr_FirstQuarterTwoThousandFifteenAcquisitionsMember
   
Other intangible assets, acquired 9,100,000us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill
/ us-gaap_BusinessAcquisitionAxis
= pwr_FirstQuarterTwoThousandFifteenAcquisitionsMember
   
Canadian Subsidiaries [Member] | Exchangeable Shares [Member]      
Business Acquisition [Line Items]      
Number of shares granted for acquired companies     3,825,971us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued
/ us-gaap_StatementEquityComponentsAxis
= pwr_ExchangeableSharesMember
/ us-gaap_StatementGeographicalAxis
= pwr_CanadianSubsidiariesMember
Series G Preferred Stock [Member]      
Business Acquisition [Line Items]      
Number of shares granted for acquired companies     1us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued
/ us-gaap_StatementClassOfStockAxis
= us-gaap_SeriesGPreferredStockMember
Series G Preferred Stock [Member] | Canadian Subsidiaries [Member] | Exchangeable Shares [Member]      
Business Acquisition [Line Items]      
Number of shares granted for acquired companies     899,858us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued
/ us-gaap_StatementClassOfStockAxis
= us-gaap_SeriesGPreferredStockMember
/ us-gaap_StatementEquityComponentsAxis
= pwr_ExchangeableSharesMember
/ us-gaap_StatementGeographicalAxis
= pwr_CanadianSubsidiariesMember
Oil and Gas Infrastructure Services Business [Member] | Canada [Member]      
Business Acquisition [Line Items]      
Number of business acquisitions 1us-gaap_NumberOfBusinessesAcquired
/ us-gaap_StatementBusinessSegmentsAxis
= pwr_OilAndGasInfrastructureServicesBusinessMember
/ us-gaap_StatementGeographicalAxis
= country_CA
  2us-gaap_NumberOfBusinessesAcquired
/ us-gaap_StatementBusinessSegmentsAxis
= pwr_OilAndGasInfrastructureServicesBusinessMember
/ us-gaap_StatementGeographicalAxis
= country_CA
Oil and Gas Infrastructure Services Business [Member] | Australia [Member]      
Business Acquisition [Line Items]      
Number of business acquisitions 1us-gaap_NumberOfBusinessesAcquired
/ us-gaap_StatementBusinessSegmentsAxis
= pwr_OilAndGasInfrastructureServicesBusinessMember
/ us-gaap_StatementGeographicalAxis
= country_AU
   
Oil and Gas Infrastructure Services Business [Member] | United States [Member]      
Business Acquisition [Line Items]      
Number of business acquisitions     1us-gaap_NumberOfBusinessesAcquired
/ us-gaap_StatementBusinessSegmentsAxis
= pwr_OilAndGasInfrastructureServicesBusinessMember
/ us-gaap_StatementGeographicalAxis
= country_US
Electric Power Infrastructure Services Business [Member] | Canada [Member]      
Business Acquisition [Line Items]      
Number of business acquisitions 1us-gaap_NumberOfBusinessesAcquired
/ us-gaap_StatementBusinessSegmentsAxis
= pwr_ElectricPowerInfrastructureServicesBusinessMember
/ us-gaap_StatementGeographicalAxis
= country_CA
  4us-gaap_NumberOfBusinessesAcquired
/ us-gaap_StatementBusinessSegmentsAxis
= pwr_ElectricPowerInfrastructureServicesBusinessMember
/ us-gaap_StatementGeographicalAxis
= country_CA
Electric Power Infrastructure Services Business [Member] | Australia [Member]      
Business Acquisition [Line Items]      
Number of business acquisitions     1us-gaap_NumberOfBusinessesAcquired
/ us-gaap_StatementBusinessSegmentsAxis
= pwr_ElectricPowerInfrastructureServicesBusinessMember
/ us-gaap_StatementGeographicalAxis
= country_AU
Electric Power Infrastructure Services Business [Member] | United States [Member]      
Business Acquisition [Line Items]      
Number of business acquisitions     1us-gaap_NumberOfBusinessesAcquired
/ us-gaap_StatementBusinessSegmentsAxis
= pwr_ElectricPowerInfrastructureServicesBusinessMember
/ us-gaap_StatementGeographicalAxis
= country_US
Electric Power Division [Member]      
Business Acquisition [Line Items]      
Goodwill acquired 949,000us-gaap_GoodwillAcquiredDuringPeriod
/ us-gaap_StatementBusinessSegmentsAxis
= pwr_ElectricPowerDivisionMember
  71,500,000us-gaap_GoodwillAcquiredDuringPeriod
/ us-gaap_StatementBusinessSegmentsAxis
= pwr_ElectricPowerDivisionMember
Oil and Gas Infrastructure Division [Member]      
Business Acquisition [Line Items]      
Goodwill acquired $ 17,382,000us-gaap_GoodwillAcquiredDuringPeriod
/ us-gaap_StatementBusinessSegmentsAxis
= pwr_OilAndGasMember
  $ 103,000,000us-gaap_GoodwillAcquiredDuringPeriod
/ us-gaap_StatementBusinessSegmentsAxis
= pwr_OilAndGasMember