Quanta Services, Inc. Quarterly report pursuant to Section 13 or 15(d)

Quarterly report pursuant to Section 13 or 15(d)

Commitments and Contingencies - Additional Information (Detail)

Commitments and Contingencies - Additional Information (Detail) (USD $)	0 Months Ended	3 Months Ended		1 Months Ended	12 Months Ended
	Oct. 09, 2013	Mar. 31, 2015 Customer	Mar. 31, 2014 Customer	Dec. 31, 2014	Dec. 31, 2014	Jul. 31, 2014	Dec. 31, 2011	Apr. 21, 2010 mi
Commitment And Contingencies [Line Items]
Outstanding capital commitment		$ 9,300,000pwr_OutstandingCapitalCommitments
Rent expense related to operating leases		49,500,000us-gaap_LeaseAndRentalExpense	34,800,000us-gaap_LeaseAndRentalExpense
Maximum guaranteed residual value		459,500,000
Number of customers representing ten percent or more of consolidated revenues		0	0
Number of customers representing ten percent or more of net position		0		0	0
Gross amount accrued for insurance claims		173,400,000		170,200,000	170,200,000
Long-term insurance claims		139,400,000pwr_LongTermInsuranceClaims		130,800,000pwr_LongTermInsuranceClaims	130,800,000pwr_LongTermInsuranceClaims
Related insurance recoveries/receivables		8,900,000us-gaap_InsuranceSettlementsReceivable		9,100,000us-gaap_InsuranceSettlementsReceivable	9,100,000us-gaap_InsuranceSettlementsReceivable
Related insurance recoveries/receivables included in prepaid expenses and other current assets		900,000		800,000	800,000
Related insurance recoveries/receivables included in other assets net		8,000,000		8,300,000	8,300,000
Letters of credit and bank guarantees under the credit facility		328,500,000
Total amount of outstanding performance bonds		2,700,000,000pwr_OutstandingPerformanceBondsAmount
Estimated cost to complete bonded projects		504,000,000
Multi-employer plan withdrawal obligation						39,600,000	32,600,000
Multi-employer plan withdrawal obligation, amount suggested by Plan which is different than amount recorded by company	6,900,000
Multi-employer plan withdrawal obligation complete withdrawal	4,800,000
Multi-employer plan withdrawal obligation accrued		2,800,000
Cash proceeds deposited in Escrow account	2,100,000
Pre-acquisition non-U.S.tax obligations and indemnification asset amount recorded		11,000,000
Pre-acquisition non-U.S.tax obligations and indemnification liability amount recorded		11,000,000
Alberta Power Line [Member]
Commitment And Contingencies [Line Items]
Length of electrical transmission line to be constructed under contract		500
Sunrise Powerlink Project [Member]
Commitment And Contingencies [Line Items]
Length of electrical transmission line to be constructed under contract								117
Proceeds from customers				65,000,000
Fiber Optic Committed Capital [Member]
Commitment And Contingencies [Line Items]
Estimated committed capital remainder of current year		26,100,000
Estimated committed capital expenditures in 2016		200,000
Vehicle Fleet Committed Capital [Member]
Commitment And Contingencies [Line Items]
Estimated committed capital remainder of current year		5,600,000
Minimum [Member]
Commitment And Contingencies [Line Items]
Multi-employer plan withdrawal obligation		40,100,000
Minimum [Member] \| Sales Revenue, Net [Member] \| Customer Concentration Risk [Member]
Commitment And Contingencies [Line Items]
Concentration risk percentage		10.00%	10.00%
Minimum [Member] \| Net Position [Member] \| Customer Concentration Risk [Member]
Commitment And Contingencies [Line Items]
Concentration risk percentage		10.00%			10.00%
Maximum [Member]
Commitment And Contingencies [Line Items]
Multi-employer plan withdrawal obligation		55,400,000
Lorenzo Benton v Telecom Network Specialists Inc [Member]
Commitment And Contingencies [Line Items]
Number of staffing Agency		29
Lorenzo Benton v Telecom Network Specialists Inc [Member] \| Class Damage [Member]
Commitment And Contingencies [Line Items]
Amount sought by plaintiff		16,000,000
Lorenzo Benton v Telecom Network Specialists Inc [Member] \| Attorney Fees [Member]
Commitment And Contingencies [Line Items]
Amount sought by plaintiff		$ 5,000,000