Income tax examination year of completion by IRS.

No definition available.

Name:	pwr_IncomeTaxExaminationYearOfCompletionByIRS
Namespace Prefix:	pwr_
Data Type:	xbrli:gYearItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of decrease reasonably possible in the next twelve months for the unrecognized tax benefit.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (d)(3)
-URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32718-109319

+ Details

Name:	us-gaap_DecreaseInUnrecognizedTaxBenefitsIsReasonablyPossible
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

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.

+ References

No definition available.

+ Details

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

- Definition

Amount of unrecognized tax benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 15A
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=65882285&loc=SL6600010-109319

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Unrecognized Tax Benefit
-URI http://asc.fasb.org/extlink&oid=6527854

+ Details

Name:	us-gaap_UnrecognizedTaxBenefits
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of decrease in unrecognized tax benefits resulting from tax positions that have been or will be taken in current period tax return.

+ References

+ Details

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

- Definition

Amount of increase in unrecognized tax benefits resulting from settlements with taxing authorities.

+ References

+ Details

Name:	us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromSettlementsWithTaxingAuthorities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of increase (decrease) in unrecognized tax benefits attributable to uncertain tax positions taken in tax returns.

+ References

+ Details

Name:	us-gaap_UnrecognizedTaxBenefitsPeriodIncreaseDecrease
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_TaxPeriodAxis=us-gaap_TaxYear2010Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeTaxAuthorityNameAxis=us-gaap_InternalRevenueServiceIRSMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_TaxPeriodAxis=us-gaap_TaxYear2011Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_TaxPeriodAxis=us-gaap_TaxYear2012Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Summary of Significant Accounting Policies (Income Taxes) - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Examination [Line Items]
Total amount of unrecognized tax benefits relating to uncertain tax positions	$ 35,240,000	$ 54,541,000	$ 50,668,000	$ 48,306,000
Amount of unrecognized tax benefits change from year end relating to uncertain tax positions	(19,300,000)
Unrecognized tax benefits decrease resulting from current period tax positions	23,400,000
Unrecognized tax benefits increase resulting from settlements with taxing authorities	4,200,000
Maximum [Member]
Income Tax Examination [Line Items]
Reasonably possible reduction to the balance of unrecognized tax benefits in succeeding 12 months	$ 12,332,000	$ 27,485,000	$ 10,221,000
Tax Year 2010 [Member] \| Internal Revenue Service (IRS) [Member]
Income Tax Examination [Line Items]
Income tax examination, year completed	2010
Tax Year 2011 [Member] \| Internal Revenue Service (IRS) [Member]
Income Tax Examination [Line Items]
Income tax examination, year completed	2011
Tax Year 2012 [Member] \| Internal Revenue Service (IRS) [Member]
Income Tax Examination [Line Items]
Income tax examination, year completed	2012