Multiemployer Plans Number

No definition available.

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- Definition

Significant Periods Of Multiemployer Contributions Exceeding Specified Percentage

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

Amount of contributions made to multiemployer plans by the employer. A multiemployer plan is a pension or postretirement benefit plan to which two or more unrelated employers contribute where assets contributed by one participating employer may be used to provide benefits to employees of other participating employers.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 80

-Section 50

-Paragraph 11

-URI http://asc.fasb.org/extlink&oid=35742057&loc=SL14450702-114947

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 80

-Section 50

-Paragraph 9

-URI http://asc.fasb.org/extlink&oid=35742057&loc=SL14450691-114947

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 80

-Section 50

-Paragraph 5

-Subparagraph (e)(1)

-URI http://asc.fasb.org/extlink&oid=35742057&loc=SL14450657-114947

+ Details

Name:	us-gaap_MultiemployerPlanPeriodContributions
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Indicate the multiemployer plan's certified zone status as currently required by the Pension Protection Act of 2006 or a subsequent amendment thereof. The zone status categories are red (critical status), orange (seriously endangered), yellow (endangered), and green (none of the above). The acceptable values are "red", "orange", "yellow", "green", "other", and "NA". A multiemployer plan is a pension or postretirement benefit plan to which two or more unrelated employers contribute where assets contributed by one participating employer may be used to provide benefits to employees of other participating employers.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 80

-Section 50

-Paragraph 5

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=35742057&loc=SL14450657-114947

+ Details

Name:	us-gaap_MultiemployerPlansCertifiedZoneStatus
Namespace Prefix:	us-gaap_
Data Type:	us-types:zoneStatusItemType
Balance Type:	na
Period Type:	duration

- Definition

Description of the significant collective-bargaining arrangements within the range of expiration dates for collective-bargaining arrangements requiring contributions to a multiemployer plan as well as other information to help investors understand the significance of the collective-bargaining agreements and when they expire. A multiemployer plan is a pension or postretirement benefit plan to which two or more unrelated employers contribute where assets contributed by one participating employer may be used to provide benefits to employees of other participating employers.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 80

-Section 50

-Paragraph 5

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=35742057&loc=SL14450657-114947

+ Details

Name:	us-gaap_MultiemployerPlansCollectiveBargainingArrangementExpirationDateDescription
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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Indicate whether a funding improvement plan or rehabilitation plan has been implemented or is pending for a pension or postretirement benefit plan to which two or more unrelated employers contribute where assets contributed by one participating employer may be used to provide benefits to employees of other participating employers. The acceptable values are "no", "pending", "implemented", "other", and "NA".

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 80

-Section 50

-Paragraph 5

-Subparagraph (f)(1)

-URI http://asc.fasb.org/extlink&oid=35742057&loc=SL14450657-114947

+ Details

Name:	us-gaap_MultiemployerPlansFundingImprovementPlanAndRehabilitationPlan
Namespace Prefix:	us-gaap_
Data Type:	us-types:fundingImprovementAndRehabilitationPlanItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_MultiemployerPlansLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Indicate whether the employer paid a surcharge to the pension or postretirement benefit plan to which two or more unrelated employers contribute where assets contributed by one participating employer may be used to provide benefits to employees of other participating employers. The acceptable values are "no", "yes", and "NA".

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 80

-Section 50

-Paragraph 5

-Subparagraph (f)(2)

-URI http://asc.fasb.org/extlink&oid=35742057&loc=SL14450657-114947

+ Details

Name:	us-gaap_MultiemployerPlansSurcharge
Namespace Prefix:	us-gaap_
Data Type:	us-types:surchargeItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_MultiemployerPlanTypeAxis=pwr_AlaskaTeamsterEmployerPensionPlanMember
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- Details

Name:	us-gaap_MultiemployerPlanTypeAxis=pwr_AllOtherPlansMember
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- Details

Name:	us-gaap_MultiemployerPlanTypeAxis=pwr_CentralPensionFundOfIuoeAndParticipatingEmployersMember
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Data Type:	na
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- Details

Name:	us-gaap_MultiemployerPlanTypeAxis=pwr_CentralStatesSoutheastAndSouthwestAreasPensionPlanMember
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Data Type:	na
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- Details

Name:	us-gaap_MultiemployerPlanTypeAxis=pwr_EighthDistrictElectricalPensionFundMember
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- Details

Name:	us-gaap_MultiemployerPlanTypeAxis=pwr_JointPensionLocalUnionOneSixFourIbewMember
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- Details

Name:	us-gaap_MultiemployerPlanTypeAxis=pwr_LaborersNationalPensionFundMember
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- Details

Name:	us-gaap_MultiemployerPlanTypeAxis=pwr_LaborersPensionTrustFundForNorthernCaliforniaMember
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- Details

Name:	us-gaap_MultiemployerPlanTypeAxis=pwr_MichiganUpperPeninsulaIntrlBrotherhoodOfElecWorkersPensionPlanMember
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- Details

Name:	us-gaap_MultiemployerPlanTypeAxis=pwr_NationalElectricalBenefitFundMember
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- Details

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- Details

Name:	us-gaap_MultiemployerPlanTypeAxis=pwr_OperatingEngineersLocalThreeTwoFourPensionFundMember
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- Details

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Employee Benefit Plans - Summary of Plan Information Relating to Participation in Multi-Employer Pension Plans (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Multiemployer Plans [Line Items]
Contributions	$ 71,204	$ 55,054	$ 63,572
National Electrical Benefit Fund [Member]
Multiemployer Plans [Line Items]
Employer Identification Number	53-0181657-001
PPA Zone Status	Green	Green
Subject to Financial Improvement/ Rehabilitation Plan	No
Contributions	20,758	17,268	18,509
Surcharge Imposed	No
Expiration Date of Collective Bargaining Agreement	Varies through August 2018
Central Pension Fund of the IUOE & Participating Employers [Member]
Multiemployer Plans [Line Items]
Employer Identification Number	36-6052390-001
PPA Zone Status	Green	Green
Subject to Financial Improvement/ Rehabilitation Plan	No
Contributions	7,847	4,259	6,843
Surcharge Imposed	No
Expiration Date of Collective Bargaining Agreement	Varies through June 2017
Pipeline Industry Pension Fund [Member]
Multiemployer Plans [Line Items]
Employer Identification Number	73-6146433-001
PPA Zone Status	Green	Green
Subject to Financial Improvement/ Rehabilitation Plan	No
Contributions	6,280	4,511	7,434
Surcharge Imposed	No
Expiration Date of Collective Bargaining Agreement	Varies through June 2017
Pipeline Industry Pension Fund [Member] \| Maximum [Member]
Multiemployer Plans [Line Items]
Plan years in which Quanta contributions were five percent or more of total plan contributions	2013
Pipeline Industry Pension Fund [Member] \| Minimum [Member]
Multiemployer Plans [Line Items]
Plan years in which Quanta contributions were five percent or more of total plan contributions	2012
Laborers National Pension Fund [Member]
Multiemployer Plans [Line Items]
Employer Identification Number	75-1280827-001
PPA Zone Status	Green	Green
Subject to Financial Improvement/ Rehabilitation Plan	No
Contributions	4,227	4,681	1,906
Surcharge Imposed	No
Expiration Date of Collective Bargaining Agreement	April 2015
Plan years in which Quanta contributions were five percent or more of total plan contributions	2013
Eighth District Electrical Pension Fund [Member]
Multiemployer Plans [Line Items]
Employer Identification Number	84-6100393-001
PPA Zone Status	Green	Green
Subject to Financial Improvement/ Rehabilitation Plan	No
Contributions	2,192	1,790	4,415
Surcharge Imposed	No
Expiration Date of Collective Bargaining Agreement	Varies through February 2018
Eighth District Electrical Pension Fund [Member] \| Maximum [Member]
Multiemployer Plans [Line Items]
Plan years in which Quanta contributions were five percent or more of total plan contributions	2013
Eighth District Electrical Pension Fund [Member] \| Minimum [Member]
Multiemployer Plans [Line Items]
Plan years in which Quanta contributions were five percent or more of total plan contributions	2012
Joint Pension Local Union 164 IBEW [Member]
Multiemployer Plans [Line Items]
Employer Identification Number	22-6031199-001
PPA Zone Status	Yellow	Yellow
Subject to Financial Improvement/ Rehabilitation Plan	Implemented
Contributions	1,816	222	515
Surcharge Imposed	No
Expiration Date of Collective Bargaining Agreement	May 2017
Plan years in which Quanta contributions were five percent or more of total plan contributions	2013
Laborers Pension Trust Fund for Northern California [Member]
Multiemployer Plans [Line Items]
Employer Identification Number	94-6277608-001
PPA Zone Status	Yellow	Yellow
Subject to Financial Improvement/ Rehabilitation Plan	Implemented
Contributions	1,357	987	21
Surcharge Imposed	Yes
Expiration Date of Collective Bargaining Agreement	June 2019
Michigan Upper Peninsula Intrl Brotherhood of Elec Workers Pension Plan [Member]
Multiemployer Plans [Line Items]
Employer Identification Number	36-3020872-001
PPA Zone Status	Yellow	Yellow
Subject to Financial Improvement/ Rehabilitation Plan	Implemented
Contributions	1,307	299	518
Surcharge Imposed	No
Expiration Date of Collective Bargaining Agreement	May 2017
Michigan Upper Peninsula Intrl Brotherhood of Elec Workers Pension Plan [Member] \| Maximum [Member]
Multiemployer Plans [Line Items]
Plan years in which Quanta contributions were five percent or more of total plan contributions	2013
Michigan Upper Peninsula Intrl Brotherhood of Elec Workers Pension Plan [Member] \| Minimum [Member]
Multiemployer Plans [Line Items]
Plan years in which Quanta contributions were five percent or more of total plan contributions	2012
Operating Engineers Local Three Two Four Pension Fund [Member]
Multiemployer Plans [Line Items]
Employer Identification Number	38-1900637-001
PPA Zone Status	Red	Red
Subject to Financial Improvement/ Rehabilitation Plan	Implemented
Contributions	1,086	818	135
Surcharge Imposed	Yes
Expiration Date of Collective Bargaining Agreement	Varies through April 2018
OE Pension Trust Fund [Member]
Multiemployer Plans [Line Items]
Employer Identification Number	94-6090764-001
PPA Zone Status	Red	Yellow
Subject to Financial Improvement/ Rehabilitation Plan	Implemented
Contributions	991	902	768
Surcharge Imposed	Yes
Expiration Date of Collective Bargaining Agreement	July 2016
Alaska Teamster Employer Pension Plan [Member]
Multiemployer Plans [Line Items]
Employer Identification Number	92-6003463-024
PPA Zone Status	Red	Red
Subject to Financial Improvement/ Rehabilitation Plan	Implemented
Contributions	516	241
Surcharge Imposed	Yes
Expiration Date of Collective Bargaining Agreement	October 2017
Central States, Southeast, and Southwest Areas Pension Plan [Member]
Multiemployer Plans [Line Items]
Employer Identification Number	36-6044243-001
PPA Zone Status	Red	Red
Subject to Financial Improvement/ Rehabilitation Plan	Implemented
Contributions			22
Surcharge Imposed	Yes
All Other Plans [Member]
Multiemployer Plans [Line Items]
Contributions	$ 22,827	$ 19,076	$ 22,486