Quanta Services (PWR) 10-Q 8 Aug 17 2017 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2017	Aug. 02, 2017
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q2
Trading Symbol	PWR
Entity Registrant Name	QUANTA SERVICES INC
Entity Central Index Key	1,050,915
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Common Stock Class Undefined
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		151,184,065
Series F Preferred Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		1
Series G Preferred Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		1
Exchangeable Shares Associated with Series F Preferred Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		3,500,000
Exchangeable Shares Associated with Series G Preferred Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		449,929
Exchangeable Shares Not Associated with Preferred Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		36,183

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Current Assets:
Cash and cash equivalents	$ 99,565	$ 112,183
Accounts receivable, net of allowances of $5,279 and $2,752	1,614,113	1,500,115
Costs and estimated earnings in excess of billings on uncompleted contracts	630,880	473,308
Inventories	94,152	88,548
Prepaid expenses and other current assets	178,489	114,591
Total current assets	2,617,199	2,288,745
Property and equipment, net of accumulated depreciation of $929,318 and $862,825	1,190,333	1,174,094
Other assets, net	145,120	101,028
Other intangible assets, net of accumulated amortization of $313,486 and $297,313	184,375	187,023
Goodwill	1,616,317	1,603,169
Total assets	5,753,344	5,354,059
Current Liabilities:
Current maturities of long-term debt and short-term debt	1,375	7,563
Accounts payable and accrued expenses	969,654	922,819
Billings in excess of costs and estimated earnings on uncompleted contracts	314,987	274,846
Total current liabilities	1,286,016	1,205,228
Long-term debt and notes payable, net of current maturities	483,638	353,562
Deferred income taxes	206,868	192,834
Insurance and other non-current liabilities	267,491	259,733
Total liabilities	2,244,013	2,011,357
Commitments and Contingencies
Equity:
Common stock, value	1	1
Additional paid-in capital	1,785,194	1,749,306
Retained earnings	1,988,185	1,876,081
Accumulated other comprehensive loss	(231,167)	(271,673)
Treasury stock, 474,065 and 0 common shares	(35,490)	(14,288)
Total stockholders’ equity	3,506,723	3,339,427
Non-controlling interests	2,608	3,275
Total equity	3,509,331	3,342,702
Total liabilities and equity	5,753,344	5,354,059
Exchangeable Shares
Equity:
Common stock, value	0	0
Series F Preferred Stock
Equity:
Preferred Stock, value	0	0
Series G Preferred Stock
Equity:
Preferred Stock, value	$ 0	$ 0

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Allowances on accounts receivable, current	$ 5,279	$ 2,752
Accumulated depreciation on property and equipment	929,318	862,825
Accumulated amortization on other intangible assets	$ 313,486	$ 297,313
Common stock, par value (in usd per share)	$ 0.00001	$ 0.00001
Common stock, shares authorized (in shares)	600,000,000	600,000,000
Common stock, shares issued (in shares)	148,964,532	144,710,773
Common stock, shares outstanding (in shares)	148,490,467	144,710,773
Treasury stock, common shares (in shares)	474,065	0
Exchangeable Shares
Common stock, shares issued (in shares)	3,986,112	6,515,453
Common stock, shares outstanding (in shares)	3,986,112	6,515,453
Exchangeable shares, par value (in usd per share)	$ 0	$ 0
Series F Preferred Stock
Preferred stock, par value (in usd per share)	$ 0.00001	$ 0.00001
Preferred stock, shares authorized (in shares)	1	1
Preferred stock, shares issued (in shares)	1	1
Preferred stock, shares outstanding (in shares)	1	1
Series G Preferred Stock
Preferred stock, par value (in usd per share)	$ 0.00001	$ 0.00001
Preferred stock, shares authorized (in shares)	1	1
Preferred stock, shares issued (in shares)	1	1
Preferred stock, shares outstanding (in shares)	1	1

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Income Statement [Abstract]
Revenues	$ 2,200,374	$ 1,792,430	$ 4,378,544	$ 3,506,167
Cost of services (including depreciation)	1,898,209	1,592,213	3,810,191	3,102,637
Gross profit	302,165	200,217	568,353	403,530
Selling, general and administrative expenses	185,880	156,607	370,432	315,131
Amortization of intangible assets	6,494	8,141	13,056	15,636
Operating income	109,791	35,469	184,865	72,763
Interest expense	(4,271)	(3,583)	(8,236)	(7,172)
Interest income	164	641	451	1,157
Other income (expense), net	(1,079)	(1,103)	(1,443)	(1,022)
Income before income taxes	104,605	31,424	175,637	65,726
Provision for income taxes	40,245	14,695	62,837	28,138
Net income	64,360	16,729	112,800	37,588
Less: Net income attributable to non-controlling interests	523	167	696	530
Net income attributable to common stock	$ 63,837	$ 16,562	$ 112,104	$ 37,058
Earnings per share attributable to common stock - basic and diluted (in usd per share)	$ 0.41	$ 0.11	$ 0.72	$ 0.23
Shares used in computing earnings per share attributable to common stock:
Weighted average basic shares outstanding (in shares)	155,090	156,128	154,859	159,577
Weighted average diluted shares outstanding (in shares)	156,165	156,130	155,745	159,579

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 64,360	$ 16,729	$ 112,800	$ 37,588
Other comprehensive income, net of tax provision:
Foreign currency translation adjustment, net of tax of $0, $0, $0 and $0	26,685	3,083	40,506	63,669
Other comprehensive income	26,685	3,083	40,506	63,669
Comprehensive income	91,045	19,812	153,306	101,257
Less: Comprehensive income attributable to non-controlling interests	523	167	696	530
Total comprehensive income attributable to Quanta stockholders	$ 90,522	$ 19,645	$ 152,610	$ 100,727

Condensed Consolidated Stateme6

Condensed Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Statement of Comprehensive Income [Abstract]
Foreign currency translation adjustment, tax	$ 0	$ 0	$ 0	$ 0

Condensed Consolidated Stateme7

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Cash Flows from Operating Activities of Continuing Operations:
Net income	$ 64,360	$ 16,729	$ 112,800	$ 37,588
Adjustments to reconcile net income to net cash provided by (used in) operating activities of continuing operations—
Depreciation	44,650	42,759	87,343	83,929
Amortization of intangible assets	6,494	8,141	13,056	15,636
Equity in (earnings) losses of unconsolidated affiliates	2,148	378	2,751	559
Amortization of debt issuance costs	338	338	678	678
(Gain) loss on sale of property and equipment	(2,007)	654	(166)	547
Foreign currency loss	641	558	862	668
Provision for (recovery of) doubtful accounts	61	56	926	(927)
Deferred income tax provision (benefit)	3,666	(7,858)	3,630	(5,142)
Non-cash stock-based compensation	11,557	9,503	23,423	23,222
Changes in operating assets and liabilities, net of non-cash transactions	(126,963)	(3,448)	(244,169)	116,863
Net cash provided by operating activities of continuing operations	4,945	67,810	1,134	273,621
Cash Flows from Investing Activities of Continuing Operations:
Proceeds from sale of property and equipment	7,543	5,165	12,344	10,254
Additions of property and equipment	(58,257)	(60,855)	(105,281)	(108,550)
Cash paid for acquisitions, net of cash acquired	(6,108)	(35)	(7,635)	(39,710)
Investments in and return of equity from unconsolidated affiliates	(9,229)	(3,163)	(12,954)	(5,388)
Cash received from (paid for) other investments, net	615	503	(1,086)	1,080
Cash withdrawn from (deposited to) restricted cash	(2,031)	42	(119)	42
Net cash used in investing activities of continuing operations	(67,467)	(58,343)	(114,731)	(142,272)
Cash Flows from Financing Activities of Continuing Operations:
Borrowings under credit facility	550,883	696,572	1,248,094	1,350,988
Payments under credit facility	(491,943)	(696,668)	(1,123,384)	(1,426,271)
Payments on other long-term debt	(1,354)	(692)	(2,883)	(5,547)
Payments on short-term debt	0	0	(2,783)	(4,711)
Distributions to non-controlling interests	(383)	0	(1,363)	0
Payments related to tax withholding for share-based compensation	(1,613)	(1,160)	(17,805)	(7,232)
Exercise of stock options	0	163	25	214
Net cash provided by (used in) financing activities of continuing operations	55,590	(1,785)	99,901	(92,559)
Discontinued operations:
Net cash used in investing activities	0	(437)	0	(6,080)
Net cash used in discontinued operations	0	(437)	0	(6,080)
Effect of foreign exchange rate changes on cash and cash equivalents	(17)	(216)	1,078	863
Net increase (decrease) in cash and cash equivalents	(6,949)	7,029	(12,618)	33,573
Cash and cash equivalents, beginning of period	106,514	155,315	112,183	128,771
Cash and cash equivalents, end of period	$ 99,565	$ 162,344	$ 99,565	$ 162,344

Business and Organization

Business and Organization	6 Months Ended
	Jun. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Business and Organization	BUSINESS AND ORGANIZATION: Quanta Services, Inc. (Quanta) is a leading provider of specialty contracting services, offering infrastructure solutions primarily to the electric power, oil and gas and communications industries in the United States, Canada and Australia and select other international markets. Quanta reports its results under two reportable segments: (1) Electric Power Infrastructure Services and (2) Oil and Gas Infrastructure Services. Electric Power Infrastructure Services Segment The Electric Power Infrastructure Services segment provides comprehensive network solutions to customers in the electric power industry. Services performed by the Electric Power Infrastructure Services segment generally include the design, installation, upgrade, repair and maintenance of electric power transmission and distribution infrastructure and substation facilities along with other engineering and technical services. This segment also provides emergency restoration services, including the repair of infrastructure damaged by inclement weather, the energized installation, maintenance and upgrade of electric power infrastructure utilizing unique bare hand and hot stick methods and Quanta’s proprietary robotic arm technologies, and the installation of “smart grid” technologies on electric power networks. In addition, this segment designs, installs and maintains renewable energy generation facilities, consisting of solar, wind and certain types of natural gas generation facilities, and related switchyards and transmission infrastructure. To a lesser extent, the segment also provides comprehensive communications infrastructure services to wireline, fiber and wireless carrier customers within the communications industry, and services in connection with the construction of electric power generation facilities, the design, installation, maintenance and repair of commercial and industrial wiring, and the installation of traffic networks and cable and control systems for light rail lines. Oil and Gas Infrastructure Services Segment The Oil and Gas Infrastructure Services segment provides comprehensive network solutions to customers involved in the development and transportation of natural gas, oil and other pipeline products. Services performed by the Oil and Gas Infrastructure Services segment generally include the design, installation, repair and maintenance of pipeline transmission and distribution systems, gathering systems, production systems, storage systems and compressor and pump stations, as well as related trenching, directional boring and mechanized welding services. In addition, this segment’s services include pipeline protection, integrity testing, rehabilitation and replacement, and fabrication of pipeline support systems and related structures and facilities. Quanta also serves the offshore and inland water energy markets, primarily providing services to oil and gas exploration platforms, including mechanical installation (or “hook-ups”), electrical and instrumentation, pre-commissioning and commissioning, coatings, fabrication and marine asset repair. To a lesser extent, this segment designs, installs and maintains fueling systems, as well as water and sewer infrastructure. Acquisitions During the second quarter of 2017 , Quanta acquired a communications infrastructure services contractor located in the United States, the results of which are generally included in Quanta’s Electric Power Infrastructure Services segment. The results of the acquired business have been included in Quanta’s consolidated financial statements beginning on the date of acquisition. This acquisition should enhance Quanta’s communications service offerings in the United States. During 2016 , Quanta completed five acquisitions. The results have been included in Quanta’s consolidated financial statements beginning on the respective dates of acquisition. See further discussion in Note 4 . See Note 13 for information on an acquisition that occurred subsequent to June 30, 2017 .

Summary of Significant Accounti

Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2017
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES: Principles of Consolidation The condensed consolidated financial statements of Quanta include the accounts of Quanta Services, Inc. and its wholly owned subsidiaries, which are also referred to as its operating units. The condensed consolidated financial statements also include the accounts of certain of Quanta’s investments in joint ventures, which are either consolidated or proportionately consolidated, as discussed in the following summary of significant accounting policies. Investments in affiliated entities in which Quanta does not have a controlling financial interest, but over which Quanta has significant influence, usually because Quanta holds a voting interest of between 20% and 50%, are accounted for using the equity method. All significant intercompany accounts and transactions have been eliminated in consolidation. Unless the context requires otherwise, references to Quanta include Quanta Services, Inc. and its consolidated subsidiaries. Interim Condensed Consolidated Financial Information These unaudited condensed consolidated financial statements have been prepared pursuant to the rules of the U.S. Securities and Exchange Commission (SEC). Certain information and footnote disclosures, normally included in annual financial statements prepared in accordance with accounting principles generally accepted in the United States (US GAAP), have been condensed or omitted pursuant to those rules and regulations. Quanta believes that the disclosures made are adequate to make the information presented not misleading. In the opinion of management, all adjustments, consisting only of normal recurring adjustments, necessary to fairly state the financial position, results of operations, comprehensive income and cash flows with respect to the interim condensed consolidated financial statements have been included. The results of operations and comprehensive income for the interim periods are not necessarily indicative of the results for the entire fiscal year. The results of Quanta have historically been subject to significant seasonal fluctuations. Quanta recommends that these unaudited condensed consolidated financial statements be read in conjunction with the audited consolidated financial statements and notes thereto of Quanta and its consolidated subsidiaries included in Quanta’s Annual Report on Form 10-K for the year ended December 31, 2016 , which was filed with the SEC on March 1, 2017 . Reclassifications Quanta reclassified certain prior period amounts related to stock-based compensation on the condensed consolidated statements of cash flows to conform to the current period presentation under a recently adopted accounting update. Additionally, certain reclassifications have been made to the prior year’s condensed consolidated statements of operations to conform to classifications in the current year. Use of Estimates and Assumptions The preparation of financial statements in conformity with US GAAP requires the use of estimates and assumptions by management in determining the reported amounts of assets and liabilities, disclosures of contingent assets and liabilities known to exist as of the date the financial statements are published, and the reported amounts of revenues and expenses recognized during the periods presented. Quanta reviews all significant estimates affecting its consolidated financial statements on a recurring basis and records the effect of any necessary adjustments prior to their publication. Judgments and estimates are based on Quanta’s beliefs and assumptions derived from information available at the time such judgments and estimates are made. Uncertainties with respect to such estimates and assumptions are inherent in the preparation of financial statements. Estimates are primarily used in Quanta’s assessment of the allowance for doubtful accounts, valuation of inventory, useful lives of assets, fair value assumptions in analyzing goodwill, other intangibles and long-lived asset impairments, equity and other investments, loan receivables, purchase price allocations, liabilities for self-insured and other claims and guarantees, multiemployer pension plan withdrawal liabilities, revenue recognition for construction contracts inclusive of contractual change orders and claims, share-based compensation, operating results of reportable segments, as well as the provision for income taxes and the calculation of uncertain tax positions. Cash and Cash Equivalents Quanta had cash and cash equivalents of $99.6 million and $112.2 million as of June 30, 2017 and December 31, 2016 . Cash consisting of interest-bearing demand deposits is carried at cost, which approximates fair value. Quanta considers all highly liquid investments with an original maturity of three months or less at the time of purchase to be cash equivalents, which are carried at fair value. At June 30, 2017 and December 31, 2016 , cash equivalents were $8.4 million and $8.8 million , and consisted primarily of money market investments and money market mutual funds and are discussed further in Fair Value Measurements below. As of June 30, 2017 and December 31, 2016 , cash and cash equivalents held in domestic bank accounts were $31.4 million and $19.5 million , and cash and cash equivalents held in foreign bank accounts were $68.2 million and $92.7 million . As of June 30, 2017 and December 31, 2016 , cash and cash equivalents held by Quanta’s investments in joint ventures, which are either consolidated or proportionately consolidated, were $13.4 million and $11.5 million , of which $10.5 million and $10.0 million related to domestic joint ventures. Cash and cash equivalents held by the joint ventures are available to support joint venture operations , but Quanta cannot utilize those assets to support its other operations. Quanta generally has no right to the joint ventures’ cash and cash equivalents other than participating in distributions and in the event of dissolution. Current and Long-Term Accounts and Notes Receivable and Allowance for Doubtful Accounts Quanta provides an allowance for doubtful accounts when collection of an account or note receivable is considered doubtful, and receivables are written off against the allowance when deemed uncollectible. Inherent in the assessment of the allowance for doubtful accounts are certain judgments and estimates regarding, among other factors, the customer’s access to capital, the customer’s willingness or ability to pay, general economic and market conditions, the ongoing relationship with the customer and uncertainties related to the resolution of disputed matters. Quanta considers accounts receivable delinquent after 30 days but does not generally include delinquent accounts in its analysis of the allowance for doubtful accounts unless the accounts receivable have been outstanding for at least 90 days. In addition to balances that have been outstanding for 90 days or more, Quanta also includes accounts receivable balances that relate to customers in bankruptcy or with other known difficulties in its analysis of the allowance for doubtful accounts. Material changes in customers’ business or cash flows, which may be impacted by negative economic and market conditions, could affect Quanta’s ability to collect amounts due from them. As of June 30, 2017 and December 31, 2016 , Quanta had allowances for doubtful accounts on current receivables of $5.3 million and $2.8 million . Long-term accounts receivable are included within other assets. Should customers experience financial difficulties or file for bankruptcy, or should anticipated recoveries relating to receivables in existing bankruptcies or other workout situations fail to materialize, Quanta could experience reduced cash flows and losses in excess of current allowances provided. The balances billed but not paid by customers pursuant to retainage provisions in certain contracts are generally due upon completion of the contracts and acceptance by the customer. Based on Quanta’s experience with similar contracts in recent years, the majority of the retainage balances at each balance sheet date are expected to be collected within the next twelve months. Current retainage balances as of June 30, 2017 and December 31, 2016 were $239.8 million and $231.0 million and were included in “Accounts receivable“. Retainage balances with settlement dates beyond the next twelve months were included in “Other assets, net”, and as of June 30, 2017 and December 31, 2016 were $31.0 million and $5.2 million . Within accounts receivable, Quanta recognizes unbilled receivables in circumstances such as when revenues have been earned and recorded but the amount cannot be billed under the terms of the contract until a later date; costs have been incurred but are yet to be billed under cost-reimbursement type contracts; or amounts arise from routine lags in billing (for example, work completed one month but not billed until the next month). These balances do not include revenues accrued for work performed under fixed-price contracts as these amounts are recorded as costs and estimated earnings in excess of billings on uncompleted contracts. At June 30, 2017 and December 31, 2016 , the balances of unbilled receivables included in accounts receivable were $247.4 million and $206.8 million . Goodwill and Other Intangibles Quanta has recorded goodwill in connection with its historical acquisitions of companies. Upon acquisition, these companies were either combined into one of Quanta’s existing operating units or managed on a stand-alone basis as an individual operating unit. Goodwill recorded in connection with these acquisitions is subject to an annual assessment for impairment, which Quanta performs at the operating unit level for each operating unit that carries a balance of goodwill. Each of Quanta’s operating units is organized into one of two internal divisions: the Electric Power Infrastructure Services Division and the Oil and Gas Infrastructure Services Division. As most of the companies acquired by Quanta provide multiple types of services for multiple types of customers, these divisional designations are based on the predominant type of work performed by each operating unit at the point in time the divisional designation is made. Goodwill is required to be measured for impairment at the reporting unit level, which represents the operating segment level or one level below the operating segment level for which discrete financial information is available. Quanta has determined that its individual operating units represent its reporting units for the purpose of assessing goodwill impairments. Quanta has the option to first assess qualitative factors to determine whether it is necessary to perform the two-step fair value-based impairment test described below. If Quanta believes that, as a result of its qualitative assessment, it is more likely than not that the fair value of a reporting unit is less than its carrying amount, the quantitative impairment test is required. Quanta can choose to perform the qualitative assessment on none, some or all of its reporting units. Quanta can also bypass the qualitative assessment for any reporting unit in any period and proceed directly to step one of the impairment test, and then resume the qualitative assessment in any subsequent period. Qualitative indicators including deterioration in macroeconomic conditions, declining financial performance, or a sustained decrease in share price, among other things, may trigger the need for annual or interim impairment testing of goodwill associated with one or all of the reporting units. Quanta’s goodwill impairment assessment is performed at year-end, or more frequently if events or circumstances arise which indicate that goodwill may be impaired. For instance, a decrease in Quanta’s market capitalization below book value, a significant change in business climate or loss of a significant customer, as well as the qualitative indicators referenced above, may trigger the need for interim impairment testing of goodwill for one or all of its reporting units. The first step of the two-step fair value based test involves comparing the fair value of each of Quanta’s reporting units with its carrying value, including goodwill. If the carrying value of the reporting unit exceeds its fair value, the second step is performed. The second step compares the carrying amount of the reporting unit’s goodwill to the implied fair value of its goodwill. If the implied fair value of goodwill is less than the carrying amount, an impairment loss would be recorded as a reduction to goodwill with a corresponding charge to operating expense. Quanta determines the fair value of its reporting units using a weighted combination of the discounted cash flow, market multiple and market capitalization valuation approaches, with heavier weighting on the discounted cash flow method, as in management’s opinion, this method currently results in the most accurate calculation of a reporting unit’s fair value. Determining the fair value of a reporting unit requires judgment and the use of significant estimates and assumptions. Such estimates and assumptions include, among others, revenue growth rates, operating margins, discount rates, weighted average costs of capital and future market conditions. Quanta believes the estimates and assumptions used in its impairment assessments are reasonable and based on available market information, but variations in any of the assumptions could result in materially different calculations of fair value and determinations of whether or not an impairment is indicated. Under the discounted cash flow method, Quanta determines fair value based on the estimated future cash flows of each reporting unit, discounted to present value using risk-adjusted industry discount rates, which reflect the overall level of inherent risk of a reporting unit and the rate of return an outside investor would expect to earn. Cash flow projections are derived from budgeted amounts and operating forecasts (typically a one-year model) plus an estimate of later period cash flows, all of which are evaluated by management. Subsequent period cash flows are developed for each reporting unit using growth rates that management believes are reasonably likely to occur, along with a terminal value derived from the reporting unit’s earnings before interest, taxes, depreciation and amortization (EBITDA). The EBITDA multiples for each reporting unit are based on trailing twelve-month comparable industry data. Under the market multiple and market capitalization approaches, Quanta determines the estimated fair value of each of its reporting units by applying transaction multiples to each reporting unit’s projected EBITDA and then averaging that estimate with similar historical calculations using either a one, two or three year average. For the market capitalization approach, Quanta adds a reasonable control premium, which is estimated as the premium that would be received in a sale of the reporting unit in an orderly transaction between market participants. For recently acquired reporting units, a step one impairment test may indicate an implied fair value that is substantially similar to the reporting unit’s carrying value. Such similarities in value are generally an indication that management’s estimates of future cash flows associated with the recently acquired reporting unit remain relatively consistent with the assumptions that were used to derive its initial fair value. During the fourth quarter of 2016 , a two-step fair-value based goodwill impairment analysis was performed for each of Quanta’s reporting units, and no reporting units were evaluated solely on a qualitative basis. Step one of the analysis indicated that the implied fair value of each of Quanta’s reporting units, other than recently acquired reporting units and the reporting units that recorded goodwill impairment charges in 2015, was substantially in excess of its carrying value. As discussed generally above, when evaluating the 2016 step one impairment test results, management considered many factors in determining whether or not an impairment of goodwill for any reporting unit was reasonably likely to occur in future periods, including future market conditions and the economic environment in which Quanta’s reporting units were operating. Additionally, management considered the sensitivity of its fair value estimates to changes in certain valuation assumptions. After taking into account a 10% decrease in the fair value of each of Quanta’s reporting units, two reporting units within Quanta’s Oil and Gas Infrastructure Division had fair values below their respective carrying values. Quanta recorded asset impairment charges for these reporting units in 2015. The fair values determined in 2016 for these reporting units were consistent with the fair values determined in 2015 and approximated their current carrying values, and therefore no impairment was required. Circumstances such as market declines, unfavorable economic conditions, loss of a major customer or other factors could increase the risk of impairment of goodwill for these reporting units in future periods. If an operating unit experiences prolonged periods of declining revenues, operating margins or both, it may be at risk of failing step one of the goodwill impairment test. Certain operating units have experienced declines over the short-term due to challenging macroeconomic conditions in certain geographic areas and low oil and natural gas prices, which have negatively impacted customer spending and resulted in project cancellations and delays. Additionally, customer capital spending has been constrained as a result of an increasingly complex regulatory and permitting environment. Certain operating units within Quanta’s Oil and Gas Infrastructure Services Division that primarily operate within the midstream and smaller-scale transmission market have continued to be negatively impacted by these factors. Goodwill and intangible assets associated with the operating units within Quanta’s Oil and Gas Infrastructure Services Division that have been significantly impacted by the factors mentioned above were $70.7 million and $11.5 million at June 30, 2017 . Quanta monitors these conditions and others to determine if it is necessary to perform step one of the fair-value based impairment test for one or more operating units prior to the annual impairment assessment. No interim impairment charges were recorded during the six months ended June 30, 2017 . Although Quanta is not aware of circumstances that would lead to a goodwill impairment at a reporting unit currently, circumstances such as a continued market decline, the loss of a major customer or other factors could impact the valuation of goodwill in the future. Quanta’s intangible assets include customer relationships, backlog, trade names, non-compete agreements, patented rights and developed technology, all subject to amortization. The value of customer relationships is estimated as of the date a business is acquired based on the value-in-use concept utilizing the income approach, specifically the excess earnings method. This analysis consists of discounting to present value the projected cash flows attributable to the customer relationships, with consideration given to customer contract renewals and estimated customer attrition rates, the importance of existing customer relationships to Quanta’s business plan, income taxes and required rates of return. Quanta values backlog for acquired businesses as of the acquisition date based upon the contractual nature of the backlog within each service line, discounted to present value. The value of trade names is estimated using the relief-from-royalty method of the income approach. This approach is based on the assumption that in lieu of ownership, a company would be willing to pay a royalty for use of the trade name. Quanta amortizes intangible assets based upon the estimated consumption of their economic benefits, or on a straight-line basis if the pattern of economic benefit cannot otherwise be reliably estimated. Intangible assets subject to amortization are reviewed for impairment and are tested for recoverability whenever events or changes in circumstances indicate that the carrying amount may not be recoverable. For instance, a significant change in business climate or a loss of a significant customer, among other things, may trigger the need for interim impairment testing of intangible assets. An impairment loss would be recognized if the carrying amount of an intangible asset is not recoverable and its carrying amount exceeds its fair value. Investments in Affiliates and Other Entities In the normal course of business, Quanta enters into various types of investment arrangements, each having unique terms and conditions. These investments may include equity interests held by Quanta in business entities, including general or limited partnerships, contractual joint ventures, or other forms of equity or profit participation. These investments may also include Quanta’s participation in different financing structures such as the extension of loans to project specific entities, the acquisition of convertible notes issued by project specific entities, or other strategic financing arrangements. Quanta also enters into strategic partnerships with customers and infrastructure investors to provide fully integrated infrastructure services on certain projects, including planning and feasibility analyses, engineering, design, procurement, construction financing, and investment and project operation and maintenance. These projects include public-private partnerships, private infrastructure projects and concessions, along with build, own, operate and transfer and build to suit arrangements. As part of this strategy, Quanta formed a partnership with select infrastructure investors that provides $750.0 million of capital, including $60.0 million from Quanta, available to invest in certain of these infrastructure projects. Wholly owned subsidiaries of Quanta serve as the general partner of this partnership and as a separately operating registered investment adviser that manages the invested capital. Quanta determines whether such investments involve a variable interest entity (VIE) based on the characteristics of the subject entity. If the entity is determined to be a VIE, then management determines if Quanta is the primary beneficiary of the entity and whether or not consolidation of the VIE is required. The primary beneficiary consolidating the VIE must normally have both (i) the power to direct the activities that most significantly affect the VIE’s economic performance and (ii) the obligation to absorb significant losses of, or the right to receive significant benefits from, the VIE. When Quanta is deemed to be the primary beneficiary, the VIE is consolidated and the other party’s equity interest in the VIE is accounted for as a non-controlling interest. In cases where Quanta determines that it has an undivided interest in the assets, liabilities, revenues and profits of an unincorporated VIE (e.g., a general partnership interest), such amounts are consolidated on a basis proportional to Quanta’s ownership interest in the unincorporated entity. Investments in entities of which Quanta is not the primary beneficiary, but over which Quanta has the ability to exercise significant influence, are accounted for using the equity method of accounting. Quanta’s share of net income or losses from unconsolidated equity investments is reported as equity in earnings (losses) of unconsolidated affiliates, which is included in “Other income (expense)” in the condensed consolidated statements of operations. Equity investments are reviewed for impairment by assessing whether any decline in the fair value of the investment below the carrying value is other than temporary. In making this determination, factors such as the ability to recover the carrying amount of the investment and the inability of the investee to sustain an earnings capacity are evaluated in determining whether a loss in value should be recognized. Any impairment losses related to investments would be recognized in equity in earnings (losses) of unconsolidated affiliates. Equity method investments are carried at original cost and are included in “Other assets, net” in the condensed consolidated balance sheets and are adjusted for Quanta’s proportionate share of the investees’ income, losses and distributions. Under the investment structure described above, Quanta has a minority ownership interest in a limited partnership that was selected during 2014 to build, own and operate a new electric transmission line and two substations in Alberta, Canada. The limited partnership contracted with a Quanta subsidiary to perform the engineering, procurement and construction (EPC) services for the project, and the Quanta subsidiary recognizes revenue and related cost of services as performance progresses on the project. However, due to Quanta’s ownership interest, a proportional amount of the EPC profit is deferred until the electric transmission line and related substations are constructed and ownership of the assets is deemed to be transferred to the third party customer. The profit deferral has been recorded as a decrease to the equity method investment included in “Other assets, net” in the accompanying condensed consolidated balance sheets and as a component of equity in earnings (losses) of unconsolidated affiliates, which is included in “Other income (expense)” in the condensed consolidated statements of operations. Revenue Recognition Quanta provides its services pursuant to master service agreements, repair and maintenance contracts and fixed price and non-fixed price installation contracts. Pricing under these contracts may be competitive unit price, cost-plus/hourly (or time and materials basis) or fixed price (or lump sum basis), and the final terms and prices of these contracts are frequently negotiated with the customer. Under unit-based contracts, the utilization of an output-based measurement is appropriate for revenue recognition, and Quanta recognizes revenue as units are completed based on pricing established with the customer for each delivered unit, which best reflects the pattern in which the obligation to the customer is fulfilled. Under cost-plus/hourly and time and materials type contracts, Quanta recognizes revenue on an input basis, as labor hours are incurred and services are performed. Revenues from fixed price contracts are recognized using the percentage-of-completion method, measured by the percentage of costs incurred to date to total estimated costs for each contract. Such contracts provide that the customer accept completion of progress to date and compensate Quanta for services rendered, which may be measured in terms of units installed, hours expended, costs incurred to date compared to total estimated contract costs or some other measure of progress. Contract costs include all direct materials, labor and subcontract costs and those indirect costs related to contract performance, such as indirect labor, supplies, tools, repairs and depreciation costs. Much of the material associated with Quanta’s work is owner-furnished and is therefore not included in contract revenues and costs. The cost estimation process is based on professional knowledge and experience of Quanta’s engineers, project managers and financial professionals. Changes in job performance, job conditions and final contract settlements are factors that influence management’s assessment of contract value and estimated costs, and as a result, the profit recognized. Actual revenues and project costs can vary, sometimes substantially, from previous estimates due to changes in a variety of factors including unforeseen circumstances not included in Quanta’s cost estimates or covered by its contracts for which it cannot obtain adequate compensation, including concealed or unknown environmental conditions; changes in the cost of equipment, commodities, materials or labor; unanticipated costs or claims due to customer-caused delays, customer failure to provide required materials or equipment, errors in engineering, specifications or designs, project modifications, or contract termination and Quanta’s inability to obtain reimbursement for such costs or recover on such claims; weather conditions; and quality issues requiring rework or replacement. These factors, along with other risks inherent in performing fixed price contracts may cause actual revenues and gross profits for a project to differ from previous estimates and could result in reduced profitability or losses on projects. Changes in these factors may result in revisions to costs and income, and their effects are recognized in the period in which the revisions are determined. These factors are routinely evaluated on a project-by-project basis throughout the project term, and the impact of corresponding revisions in management’s estimates of contract value, contract cost and contract profit are recorded as necessary in the period in which the revisions are determined. Provisions for losses on uncompleted contracts are made in the period in which such losses are determined to be probable and the amount can be reasonably estimated. Quanta’s operating results for the three months ended June 30, 2017 were positively impacted by 10.2% as a result of aggregate changes in contract estimates related to projects that were in progress at March 31, 2017 . Included within the operating results for the three months ended June 30, 2017 were positive changes in estimates of $24.6 million primarily related to favorable mitigation of project risks and the release of related cost contingencies on two natural gas pipeline projects nearing completion in the quarter. Quanta’s operating results for the six months ended June 30, 2017 were impacted by less than 5% as a result of aggregate changes in contract estimates related to projects that were in progress at December 31, 2016 . Quanta’s operating results for the three months ended June 30, 2016 were negatively impacted by 9.2% as a result of aggregate changes in contract estimates related to projects that were in progress at March 31, 2016. Quanta’s operating results for the six months ended June 30, 2016 were negatively impacted by 6.7% as a result of aggregate changes in contract estimates related to projects that were in progress at December 31, 2015 . Operating results for the three and six months ended June 30, 2016 included losses on a power plant construction project in Alaska due to performance issues that resulted in an increase of the estimated total costs necessary to complete the project. During the three and six months ended June 30, 2016 , Quanta recognized project losses of $30.5 million and $51.8 million related to this project. This project was substantially completed during the fourth quarter of 2016. The losses on this project were partially offset by the aggregate positive impact of numerous individually immaterial changes in profitability generally due to better than expected performance on projects that were in progress at December 31, 2015 . The current asset “Costs and estimated earnings in excess of billings on uncompleted contracts” represents revenues recognized in excess of amounts billed for fixed price contracts. The current liability “Billings in excess of costs and estimated earnings on uncompleted contracts” represents billings in excess of revenues recognized for fixed price contracts. Quanta may incur costs subject to change orders, whether approved or unapproved by the customer, and/or claims related to certain contracts. Quanta determines the probability that such costs will be recovered based upon evidence such as past practices with the customer, specific discussions or preliminary negotiations with the customer or verbal approvals. Quanta treats items as costs of contract performance in the period incurred if it is not probable that the costs will be recovered or will recognize revenue if it is probable that the contract price will be adjusted and can be reliably estimated. As of June 30, 2017 and December 31, 2016 , Quanta recognized revenues of $118.9 million and $137.8 million related to change orders and/or claims that were in the process of being negotiated in the normal course of business. These aggregate contract price adjustments represent management’s best estimate of additional contract revenues which have been earned and

New Accounting Pronouncements

New Accounting Pronouncements	6 Months Ended
	Jun. 30, 2017
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
New Accounting Pronouncements	NEW ACCOUNTING PRONOUNCEMENTS: Adoption of New Accounting Pronouncements In July 2015 , the FASB issued an update that requires inventory to be measured at the lower of either cost or net realizable value. When evidence exists that the net realizable value of inventory is lower than its cost, the difference will be recognized as a loss in earnings in the period in which it occurs. Quanta adopted this guidance effective January 1, 2017 , and the adoption of the update did not have a significant impact on Quanta’s consolidated financial statements or related disclosures. In March 2016 , the FASB issued an update that amends the accounting for share-based payments in several key areas, including the treatment and cash flow presentation of tax effects related to the settlement of share-based payments and the accounting for forfeitures of share-based awards. The new guidance requires companies with share-based payments to record all tax effects related thereto at settlement (or expiration) through income tax expense on the statement of operations rather than through additional paid-in capital (APIC) within equity. This update also requires excess tax benefits to be classified as an operating activity on the statement of cash flows rather than reclassified as a financing activity and requires cash paid by an employer when withholding shares for the employee portion of taxes to be presented as a financing activity. The update also allows companies to either account for forfeitures of share-based payments as they occur or to estimate forfeitures. This guidance is required to be applied prospectively except for the classification of cash related to tax withholding, which requires retrospective application. Quanta adopted this guidance effective January 1, 2017 and will continue to estimate forfeitures of share-based payments. Quanta anticipates increased volatility of income tax expense after adoption of this guidance, and during the three and six months ended June 30, 2017 recorded income tax benefits of $0.1 million and $5.0 million related to the settlement of share-based awards. APIC was not adjusted for amounts recorded prior to 2017, and therefore Quanta’s retained earnings were not affected by the adoption of this guidance. Additionally, $1.2 million and $7.2 million were reclassified from operating activities to financing activities on the statements of cash flows for the three and six months ended June 30, 2016 associated with cash paid by Quanta to satisfy tax withholding obligations for share-settled awards. Further, the presentation of excess tax benefits on the statements of cash flows is now shown as cash flows from operating activities rather than in financing activities. The excess tax benefits reclassified to operating activities for both the three and six months ended June 30, 2016 were $0.1 million . In October 2016 , the FASB issued an update that amends the consolidation guidance related to how a reporting entity that is the single decision maker of a VIE should treat indirect interests in the VIE held through related parties that are under common control with the reporting entity when determining whether it is the primary beneficiary of a VIE. A reporting entity has an indirect interest in a VIE if it has a direct interest in a related party that, in turn, has a direct interest in the VIE. Quanta adopted this guidance on January 1, 2017 , and the adoption of the update did not have a significant impact on its consolidated financial statements or related disclosures. Accounting Standards Not Yet Adopted In May 2014 , the FASB issued an update that supersedes most current revenue recognition guidance, as well as some cost recognition guidance. The update requires that the recognition of revenue related to the transfer of goods or services to customers reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. This update also requires new qualitative and quantitative disclosures about the nature, amount, timing and uncertainty of revenues and cash flows arising from customer contracts, including significant judgments and changes in judgments, information about contract balances and performance obligations, and assets recognized from costs incurred to obtain or fulfill a contract. In July 2015, the FASB affirmed its proposal to defer the effective date until fiscal years beginning on or after December 15, 2017 . The guidance can be applied on a full retrospective or modified retrospective basis whereby the entity records a cumulative effect of initially applying this update at the date of initial application. Quanta is currently evaluating the potential impact of this update on its consolidated financial statements and anticipates adopting the update using the modified retrospective transition method, which may result in a cumulative-effect adjustment recorded in retained earnings. While Quanta is still evaluating the requirements of this update, it currently does not expect the update to materially affect its results of operations, financial position or cash flows. This preliminary conclusion is based on Quanta’s belief that it will generally continue to recognize revenues from long-term service contracts over time as services are performed and the underlying obligation to the customer is fulfilled. Quanta has identified and is in the process of implementing changes to its processes and internal controls to meet the reporting and disclosure requirements of this update and will adopt this update effective January 1, 2018 . In January 2016 , the FASB issued an update that addresses certain aspects of recognition, measurement, presentation, and disclosure of financial instruments to provide users of financial statements with more decision-useful information. The new standard is effective for interim and annual periods beginning after December 15, 2017 . Quanta is evaluating the impact of the new standard on its consolidated financial statements and will adopt the new standard by January 1, 2018 . In February 2016 , the FASB issued an update that requires companies to recognize on the balance sheet the contractual right to use assets and liabilities corresponding to the rights and obligations created by lease contracts. The new standard is effective for interim and annual periods beginning after December 15, 2018 . While Quanta continues to evaluate the effect of the standard on its consolidated financial statements, it is anticipated that the adoption of the standard will materially impact its statement of financial position. In June 2016 , the FASB issued an update that will change the way companies measure credit losses for most financial assets and certain other instruments that are not measured at fair value through net income. The update will require companies to use an “expected loss” model for instruments measured at amortized cost and to record allowances for available-for-sale debt securities rather than reduce the carrying amounts. The update will also require disclosure of information regarding how a company developed its allowance, including changes in the factors that influenced management’s estimate of expected credit losses and the reasons for those changes. Companies will apply this standard’s provisions as a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is effective. The new standard is effective for interim and annual reporting periods beginning after December 15, 2019 . Quanta is currently evaluating the potential impact of this authoritative guidance on its consolidated financial statements and will adopt this guidance by January 1, 2020 . In August 2016 , the FASB issued an update intended to standardize the classification of certain transactions on the statement of cash flows . These transactions include contingent consideration payments made after a business combination, proceeds from the settlement of corporate-owned life insurance policies and distributions received from equity method investments. The new standard is effective for interim and annual reporting periods beginning after December 15, 2017 and requires application using a retrospective transition method. Quanta is currently evaluating the potential impact of this authoritative guidance on its consolidated financial statements and will adopt this guidance by January 1, 2018 . In October 2016 , the FASB issued an update that will require a reporting entity to recognize the tax expense from the sale of an asset in the seller’s tax jurisdiction when the transfer occurs, even though the pre-tax effects of that transaction are eliminated in consolidation. Any deferred tax asset that arises in the buyer’s jurisdiction would also be recognized at the time of the transfer. The new guidance will not apply to intra-entity transfers of inventory. The income tax consequences from the sale of inventory from one member of a consolidated entity to another will continue to be deferred until the inventory is sold to a third party. The new standard is effective for interim and annual reporting periods beginning after December 15, 2017 . The modified retrospective method will be required for transition to the new guidance, with a cumulative-effect adjustment recorded in retained earnings as of the beginning of the period of adoption. Quanta is currently evaluating the potential impact of this authoritative guidance on its consolidated financial statements and will adopt this guidance by January 1, 2018 . In November 2016 , the FASB issued an update intended to standardize the classification of restricted cash and cash equivalents transactions on the statement of cash flows . The new standard is effective for interim and annual reporting periods beginning after December 15, 2017 . The retrospective transition method will be required for this new guidance. Quanta is currently evaluating the potential impact of this authoritative guidance on its consolidated financial statements and will adopt this guidance by January 1, 2018 . In January 2017 , the FASB issued an update intended to clarify whether transactions should be accounted for as acquisitions or disposals of assets or businesses. When substantially all of the fair value of the gross assets acquired or disposed of is concentrated in a single identifiable asset or group of similar identifiable assets, the asset or group is not a business. The update will require, among other things, that to be considered a business, a set of assets and activities must include, at a minimum, an input and a substantive process that together significantly contribute to the ability to create output. Additionally, the update will remove the evaluation of whether a market participant could replace missing elements in order to consider the set of assets and activities a business, will provide more stringent criteria for sets without outputs and will narrow the definition of output. The new standard is effective for interim and annual reporting periods beginning after December 15, 2017 and the prospective transition method will be required for this new guidance. Quanta is currently evaluating the potential impact of this authoritative guidance on its consolidated financial statements and will adopt this guidance by January 1, 2018 . Also in January 2017 , the FASB issued an update intended to simplify the subsequent measurement of goodwill by eliminating the second step in the current two-step goodwill impairment test. The update will require an entity to perform its annual, or interim, goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount. An entity will recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value, if applicable. Additionally, the update will eliminate the requirement that a reporting unit with a zero or negative carrying amount perform a qualitative assessment and the second step of the two-step goodwill impairment test and will instead require disclosure of the amount of goodwill allocated to each reporting unit with a zero or negative carrying amount of net assets. This update is effective for interim and annual reporting periods beginning after December 15, 2019 . The prospective transition method will be required for this new guidance. Quanta is currently evaluating the potential impact of this authoritative guidance on its consolidated financial statements and will adopt this guidance by January 1, 2020 . In May 2017 , the FASB issued an update providing guidance about which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting. A modification should be accounted for unless the following characteristics of the award are unchanged: the fair value, the vesting conditions and the classification as an equity instrument or a liability instrument. The update is effective for interim and annual periods beginning after December 15, 2017 and is required to be applied prospectively. Quanta is evaluating the impact of the new accounting standard on its consolidated financial statements and will adopt the new standard by January 1, 2018 .

Acquisitions

Acquisitions	6 Months Ended
	Jun. 30, 2017
Business Combinations [Abstract]
Acquisitions	ACQUISITIONS: During the second quarter of 2017 , Quanta acquired a communications infrastructure services contractor located in the United States, the results of which are generally included in Quanta’s Electric Power Infrastructure Services segment. The aggregate consideration for this acquisition consisted of $5.6 million paid or payable in cash, subject to certain adjustments, and 288,666 shares of Quanta common stock, with a value of $8.3 million as of the acquisition date. The acquired business’s results have been included in Quanta’s consolidated financial statements beginning on the date of acquisition. During 2016 , Quanta completed five acquisitions. The results of four of the acquired companies are generally included in Quanta’s Electric Power Infrastructure Services segment. These companies included an electrical infrastructure services company located in Australia, a utility contracting company located in Canada, a full service medium- and high-voltage powerline contracting company located in the United States and a communications services company located in Canada. Quanta also acquired a pipeline service contractor located in the United States, the results of which are generally included in Quanta’s Oil and Gas Infrastructure Services segment. The aggregate consideration for these acquisitions consisted of $75.9 million paid or payable in cash, subject to certain adjustments, 70,840 shares of Quanta common stock valued at $1.5 million as of the settlement date of the applicable acquisition, and contingent consideration payments of up to $39.5 million , which will be paid if certain financial targets are achieved. Based on the estimated fair value of this contingent consideration, Quanta recorded an $18.7 million liability. The results have been included in Quanta’s consolidated financial statements beginning on the respective dates of acquisition. Quanta is in the process of finalizing its assessments of the fair values of the acquired assets and assumed liabilities related to businesses acquired subsequent to June 30, 2016 , and further adjustments to the purchase price allocations may occur. Quanta expects to complete the purchase accounting process as soon as practicable but no later than one year from the acquisition dates with possible updates primarily related to certain tax estimates. The aggregate purchase consideration of the businesses acquired subsequent to June 30, 2016 through June 30, 2017 was preliminarily allocated to acquired assets and assumed liabilities, which resulted in a preliminary allocation of $22.9 million of net tangible assets, $19.2 million of goodwill and $10.2 million of other intangible assets. The following table summarizes the aggregate consideration paid or payable as of June 30, 2017 for the 2017 acquisition and 2016 acquisitions and presents the allocation of these amounts to the net tangible and identifiable intangible assets based on their estimated fair values as of the respective acquisition dates, inclusive of any purchase price adjustments. This allocation requires a significant use of estimates and is based on information that was available to management at the time these consolidated financial statements were prepared (in thousands). 2017 2016 Consideration: Value of Quanta common stock issued $ 8,267 $ 1,508 Cash paid or payable 5,554 75,941 Contingent consideration — 18,683 Fair value of total consideration transferred or estimated to be transferred $ 13,821 $ 96,132 Current assets $ 6,365 $ 24,233 Property and equipment 890 44,863 Other assets 12 2,553 Identifiable intangible assets 7,053 11,467 Current liabilities (1,983 ) (12,097 ) Deferred tax liabilities, net — (13,484 ) Other long-term liabilities — (5,326 ) Total identifiable net assets 12,337 52,209 Goodwill 1,484 43,923 $ 13,821 $ 96,132 The fair value of current assets acquired related to the 2017 acquisition and the 2016 acquisitions included accounts receivable with a fair value of $6.3 million and $14.4 million . Goodwill represents the excess of the purchase price over the net amount of the fair values assigned to assets acquired and liabilities assumed. The 2017 and 2016 acquisitions strategically expanded Quanta’s Canadian, Australian and domestic electric power, oil and gas service and communications offerings, which Quanta believes contributes to the recognition of the goodwill. In connection with the 2017 acquisition, goodwill of $1.5 million was recorded for the acquired business that was included within Quanta’s Electric Power Infrastructure Services Division on the date of acquisition. In connection with the 2016 acquisitions, goodwill of $23.6 million was recorded for the acquired businesses that were included within Quanta’s Electric Power Infrastructure Services Division and $20.3 million was recorded for the business acquired that was included within Quanta’s Oil and Gas Infrastructure Services Division on the dates of acquisition. Goodwill of $1.5 million and $2.0 million related to the 2017 acquisition and 2016 acquisitions is expected to be deductible for income tax purposes. The following table summarizes the estimated fair values of identifiable intangible assets for the 2017 acquisition as of the acquisition date and the related weighted average amortization periods by type (in thousands, except for weighted average amortization periods, which are in years). Estimated Weighted Average Fair Value at Amortization Period in Years Acquisition Date at Acquisition Date Customer relationships $ 6,625 5.0 Non-compete agreements 428 5.0 Total intangible assets subject to amortization acquired in 2017 acquisition $ 7,053 5.0 The unaudited supplemental pro forma results of operations have been provided for illustrative purposes only and do not purport to be indicative of the actual results that would have been achieved by the combined companies for the periods presented or that may be achieved by the combined companies in the future. Future results may vary significantly from the results reflected in the following pro forma financial information because of future events and transactions, as well as other factors (in thousands, except per share amounts): Three Months Ended Six Months Ended June 30, June 30, 2017 2016 2017 2016 Revenues $ 2,203,724 $ 1,806,214 $ 4,386,919 $ 3,541,361 Gross profit $ 303,222 $ 203,354 $ 570,996 $ 410,576 Selling, general and administrative expenses $ 186,512 $ 158,603 $ 372,012 $ 319,799 Amortization of intangible assets $ 6,729 $ 8,683 $ 13,644 $ 16,866 Net income $ 64,472 $ 17,080 $ 113,074 $ 38,298 Net income attributable to common stock $ 63,949 $ 16,913 $ 112,378 $ 37,768 Earnings per share attributable to common stock - basic and diluted $ 0.41 $ 0.11 $ 0.72 $ 0.24 The pro forma combined results of operations for the three and six months ended June 30, 2017 and 2016 have been prepared by adjusting the historical results of Quanta to include the historical results of the 2017 acquisition as if it occurred January 1, 2016 . The pro forma combined results of operations for the three and six months ended June 30, 2016 have been prepared by adjusting the historical results of Quanta to include the historical results of the 2016 acquisitions as if they occurred January 1, 2015 . These pro forma combined historical results were also adjusted for the following: a reduction of interest expense as a result of the repayment of outstanding indebtedness of the acquired businesses, a reduction of interest income as a result of the cash consideration paid net of cash received, an increase in amortization expense due to the incremental intangible assets recorded related to the 2017 acquisition and the 2016 acquisitions, an increase or decrease in depreciation expense within cost of services related to the net impact of adjusting acquired property and equipment to the acquisition date fair value and conforming depreciable lives with Quanta’s accounting policies, an increase in the number of outstanding shares of Quanta common stock and certain reclassifications to conform the acquired companies’ presentation to Quanta’s accounting policies. The pro forma results of operations do not include any adjustments to eliminate the impact of acquisition related costs or any cost savings or other synergies that resulted or may result from the acquisitions. As noted above, the pro forma results of operations do not purport to be indicative of the actual results that would have been achieved by the combined company for the periods presented or that may be achieved by the combined company in the future. Revenues of approximately $2.2 million and a loss before taxes of approximately $1.8 million , which included $2.3 million of acquisitions costs, were included in Quanta’s consolidated results of operations for the three and six months ended June 30, 2017 related to the 2017 acquisition following its acquisition date.

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	6 Months Ended
	Jun. 30, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Other Intangible Assets	GOODWILL AND OTHER INTANGIBLE ASSETS: A summary of changes in Quanta’s goodwill is as follows (in thousands): Electric Power Infrastructure Services Division Oil and Gas Infrastructure Services Division Total Balance at December 31, 2016: Goodwill $ 1,253,979 $ 388,923 $ 1,642,902 Accumulated impairment — (39,733 ) (39,733 ) 1,253,979 349,190 1,603,169 Goodwill acquired during 2017 1,484 — 1,484 Purchase price allocation adjustments (619 ) (659 ) (1,278 ) Foreign currency translation adjustments 7,892 5,050 12,942 Balance at June 30, 2017: Goodwill 1,262,736 394,186 1,656,922 Accumulated impairment — (40,605 ) (40,605 ) $ 1,262,736 $ 353,581 $ 1,616,317 Adjustments primarily represent changes in deferred tax liability estimates and would not have had a material impact on the consolidated financial statements in prior periods had these adjustments been booked at the respective acquisition dates. Also, as described in Note 2, Quanta’s operating units are organized into one of Quanta’s two internal divisions and, accordingly, the goodwill associated with the operating units has been aggregated on a divisional basis in the table above. These divisions are closely aligned with Quanta’s reportable segments and operating units are assigned to a division based on the predominant type of work performed. From time to time, operating units may be reorganized between divisions as business environments evolve. Quanta’s intangible assets subject to amortization and the remaining weighted average amortization periods related to such assets were as follows (in thousands except for weighted average amortization periods, which are in years): As of As of As of June 30, 2017 December 31, 2016 June 30, 2017 Intangible Assets Accumulated Amortization Intangible Assets, Net Intangible Assets Accumulated Amortization Intangible Assets, Net Remaining Weighted Average Amortization Period in Years Customer relationships $ 254,989 $ (121,292 ) $ 133,697 $ 244,329 $ (110,640 ) $ 133,689 8.2 Backlog 134,967 (134,295 ) 672 133,592 (132,441 ) 1,151 0.7 Trade names 55,439 (14,708 ) 40,731 54,723 (12,855 ) 41,868 17.3 Non-compete agreements 29,958 (26,470 ) 3,488 29,212 (25,546 ) 3,666 2.9 Patented rights and developed technology 22,508 (16,721 ) 5,787 22,480 (15,831 ) 6,649 3.7 Total intangible assets subject to amortization $ 497,861 $ (313,486 ) $ 184,375 $ 484,336 $ (297,313 ) $ 187,023 9.9 Amortization expense for intangible assets was $6.5 million and $8.1 million for the three months ended June 30, 2017 and 2016 and $13.1 million and $15.6 million for the six months ended June 30, 2017 and 2016 . The estimated future aggregate amortization expense of intangible assets subject to amortization as of June 30, 2017 is set forth below (in thousands): For the Fiscal Year Ending December 31, Remainder of 2017 $ 13,618 2018 26,061 2019 24,015 2020 22,705 2021 20,368 Thereafter 77,608 Total $ 184,375

Per Share Information

Per Share Information	6 Months Ended
	Jun. 30, 2017
Earnings Per Share [Abstract]
Per Share Information	PER SHARE INFORMATION: The amounts used to compute the basic and diluted earnings per share attributable to common stock for the three and six months ended June 30, 2017 and 2016 are illustrated below (in thousands): Three Months Ended Six Months Ended June 30, June 30, 2017 2016 2017 2016 Amounts attributable to common stock: Net income attributable to common stock $ 63,837 $ 16,562 $ 112,104 $ 37,058 Weighted average shares: Weighted average shares outstanding for basic earnings per share attributable to common stock 155,090 156,128 154,859 159,577 Effect of dilutive unvested non-participating stock-based awards 1,075 2 886 2 Weighted average shares outstanding for diluted earnings per share attributable to common stock 156,165 156,130 155,745 159,579 For purposes of calculating diluted earnings per share attributable to common stock, there were no adjustments required to derive Quanta’s net income attributable to common stock. Exchangeable shares that were issued pursuant to certain of Quanta’s historical acquisitions (as further discussed in Note 8), which are exchangeable on a one-for-one basis with shares of Quanta common stock, have been included in the calculation of weighted average shares outstanding for basic and diluted earnings per share attributable to common stock for the portion of the periods that they were outstanding. Additionally, unvested stock-based awards that contain non-forfeitable rights to dividends or dividend equivalents (participating) have been included in the calculation of basic and diluted earnings per share attributable to common stock for the portion of the periods that they were outstanding. Diluted earnings per share attributable to common stock is computed using the weighted average number of common shares outstanding during the period adjusted for all potentially dilutive common stock equivalents, except in cases where the effect of the common stock equivalents would be antidilutive.

Debt Obligations

Debt Obligations	6 Months Ended
	Jun. 30, 2017
Debt Disclosure [Abstract]
Debt Obligations	DEBT OBLIGATIONS: Quanta’s long-term debt obligations consisted of the following (in thousands): June 30, 2017 December 31, 2016 Borrowings under credit facility $ 480,690 $ 351,341 Other long-term debt, interest rates ranging from 2.4% to 4.3% 1,831 3,305 Capital leases, interest rates ranging from 2.5% to 3.8% 2,492 3,744 Total long-term debt obligations 485,013 358,390 Less — Current maturities of long-term debt 1,375 4,828 Total long-term debt obligations, net of current maturities $ 483,638 $ 353,562 Quanta’s current maturities of long-term debt and short-term debt consisted of the following (in thousands): June 30, 2017 December 31, 2016 Short-term debt $ — $ 2,735 Current maturities of long-term debt 1,375 4,828 Current maturities of long-term debt and short-term debt $ 1,375 $ 7,563 Credit Facility On December 18, 2015, Quanta entered into an amended and restated credit agreement with various lenders that provides for a $1.81 billion senior secured revolving credit facility maturing on December 18, 2020 . The entire amount available under the credit facility may be used by Quanta for revolving loans and letters of credit in U.S. dollars and certain alternative currencies. Up to $600.0 million of the credit facility may be used by certain subsidiaries of Quanta for revolving loans and letters of credit in certain alternative currencies. Up to $100.0 million of the credit facility may be used for swing line loans in U.S. dollars, up to $50.0 million of the credit facility may be used for swing line loans in Canadian dollars and up to $30.0 million of the facility may be used for swing line loans in Australian dollars. In addition, subject to the conditions specified in the credit agreement, Quanta has the option to increase the revolving commitments by up to $400.0 million from time to time upon receipt of additional commitments from new or existing lenders. Borrowings under the credit agreement are to be used to refinance existing indebtedness and for working capital, capital expenditures and other general corporate purposes. As of June 30, 2017 , Quanta had $324.7 million of outstanding letters of credit and bank guarantees, $225.1 million of which were denominated in U.S. dollars and $99.6 million of which were denominated in currencies other than the U.S. dollar, primarily in Australian or Canadian dollars. Quanta also had $480.7 million of outstanding revolving loans under the credit facility, $326.4 million of which were denominated in U.S. dollars and $154.3 million of which were denominated in Canadian dollars. The remaining $1.00 billion was available for revolving loans or new letters of credit or bank guarantees. Borrowings under Quanta’s credit facility and the applicable interest rates during the three and six months ended June 30, 2017 and 2016 were as follows (dollars in thousands): Three Months Ended Six Months Ended June 30, June 30, 2017 2016 2017 2016 Maximum amount outstanding under the credit facility during the period $ 601,062 $ 465,599 $ 601,062 $ 518,607 Average daily amount outstanding under the credit facility $ 518,779 $ 426,172 $ 464,432 $ 449,101 Weighted-average interest rate 2.49 % 2.17 % 2.54 % 2.08 % Under the current credit agreement, amounts borrowed in U.S. dollars bear interest, at Quanta’s option, at a rate equal to either (i) the Eurocurrency Rate (as defined in the credit agreement) plus 1.125% to 2.125% , as determined based on Quanta’s Consolidated Leverage Ratio (as described below), or (ii) the Base Rate (as described below) plus 0.125% to 1.125% , as determined based on Quanta’s Consolidated Leverage Ratio. Amounts borrowed as revolving loans under the credit agreement in any currency other than U.S. dollars bear interest at a rate equal to the Eurocurrency Rate plus 1.125% to 2.125% , as determined based on Quanta’s Consolidated Leverage Ratio. Standby letters of credit issued under the credit agreement are subject to a letter of credit fee of 1.125% to 2.125% , based on Quanta’s Consolidated Leverage Ratio, and Performance Letters of Credit (as defined in the credit agreement) issued under the credit agreement in support of certain contractual obligations are subject to a letter of credit fee of 0.675% to 1.275% , based on Quanta’s Consolidated Leverage Ratio. Quanta is also subject to a commitment fee of 0.20% to 0.40% , based on its Consolidated Leverage Ratio, on any unused availability under the credit agreement. The Consolidated Leverage Ratio is the ratio of Quanta’s Consolidated Funded Indebtedness to Consolidated EBITDA (as those terms are defined in the credit agreement). For purposes of calculating Quanta’s Consolidated Leverage Ratio, Consolidated Funded Indebtedness is reduced by available cash and Cash Equivalents (as defined in the credit agreement) in excess of $25.0 million . The Base Rate equals the highest of (i) the Federal Funds Rate (as defined in the credit agreement) plus 0.5% , (ii) the prime rate publicly announced by Bank of America, N.A. and (iii) the Eurocurrency Rate plus 1.00% . Subject to certain exceptions, the credit agreement is secured by substantially all the assets of Quanta and Quanta’s wholly owned U.S. subsidiaries and by a pledge of all of the capital stock of Quanta’s wholly owned U.S. subsidiaries and 65% of the capital stock of direct foreign subsidiaries of Quanta’s wholly owned U.S. subsidiaries. Quanta’s wholly owned U.S. subsidiaries also guarantee the repayment of all amounts due under the credit agreement. Subject to certain conditions, all collateral will automatically be released from the liens at any time Quanta maintains an Investment Grade Rating (defined in the credit agreement as two of the following three conditions being met: (i) a corporate credit rating that is BBB- or higher by Standard & Poor’s Rating Services, (ii) a corporate family rating that is Baa3 or higher by Moody’s Investors Services, Inc. or (iii) a corporate credit rating that is BBB- or higher by Fitch Ratings, Inc.). The credit agreement contains certain covenants, including a maximum Consolidated Leverage Ratio and a minimum Consolidated Interest Coverage Ratio (as defined in the credit agreement). The credit agreement also limits certain acquisitions, mergers and consolidations, indebtedness, asset sales and prepayments of indebtedness and, subject to certain exceptions, prohibits liens on Quanta’s assets. The credit agreement allows cash payments for dividends and stock repurchases subject to compliance with the following requirements (after giving effect to the dividend or stock repurchase): (i) no default or event of default under the credit agreement; (ii) continued compliance with the financial covenants in the credit agreement; and (iii) at least $100.0 million of availability under the credit agreement and/or cash and cash equivalents on hand. As of June 30, 2017 , Quanta was in compliance with all of the covenants in the credit agreement. The credit agreement provides for customary events of default and contains cross-default provisions with Quanta’s underwriting, continuing indemnity and security agreement with its sureties and all of Quanta’s other debt instruments exceeding $100.0 million in borrowings or availability. If an Event of Default (as defined in the credit agreement) occurs and is continuing, on the terms and subject to the conditions set forth in the credit agreement, the lenders may declare all amounts outstanding and accrued and unpaid interest immediately due and payable, require that Quanta provide cash collateral for all outstanding letter of credit obligations, terminate the commitments under the credit agreement, and foreclose on the collateral.

Equity

Equity	6 Months Ended
	Jun. 30, 2017
Equity [Abstract]
Equity	EQUITY: Exchangeable Shares and Series F and Series G Preferred Stock In connection with certain Canadian acquisitions, the former owners of the acquired companies received exchangeable shares of certain Canadian subsidiaries of Quanta, which may be exchanged at the option of the holders for Quanta common stock on a one -for-one basis. The holders of exchangeable shares can make an exchange only once in any calendar quarter and must exchange a minimum of either 50,000 shares or, if less, the total number of remaining exchangeable shares registered in the name of the holder making the request. Additionally, in connection with two of such acquisitions, Quanta issued one share of Quanta Series F preferred stock and one share of Quanta Series G preferred stock (the Preferred Stock) to voting trusts on behalf of the respective holders of the exchangeable shares issued in such acquisitions. Each share of the Preferred Stock provides the holders of such exchangeable shares voting rights in Quanta common stock equivalent to the number of exchangeable shares outstanding. The holders of exchangeable shares associated with the Preferred Stock have rights equivalent to Quanta common stockholders with respect to voting, dividends and other economic rights. The holders of exchangeable shares not associated with the Preferred Stock have rights equivalent to Quanta common stockholders with respect to dividends and other economic rights but do not have voting rights. During the three months ended June 30, 2017 and 2016 , no exchangeable shares were exchanged for Quanta common stock. During the six months ended June 30, 2017 and 2016 , 2.5 million and no exchangeable shares were exchanged for Quanta common stock. As of June 30, 2017 , both shares of the Preferred Stock remained outstanding and 4.0 million exchangeable shares remained outstanding, of which 3.9 million were associated with the Preferred Stock. Treasury Stock Shares withheld for tax withholding obligations Under the stock incentive plans described in Note 9, the tax withholding obligations of employees upon vesting of restricted stock, RSUs and performance units settled in common stock are typically satisfied by Quanta making such tax payments and withholding the number of vested shares having a value on the date of vesting equal to the tax withholding obligation. For the settlement of these employee tax liabilities, Quanta withheld 0.5 million and 0.4 million shares of Quanta common stock during the six months ended June 30, 2017 and 2016 , with a total market value of $17.8 million and $7.2 million . These shares and the related costs to acquire them were accounted for as adjustments to the balance of treasury stock. Notional amounts recorded related to deferred compensation plans For RSUs and performance units that vest but the settlement of which are deferred under Quanta’s deferred compensation plans, Quanta records an amount to treasury stock and an offsetting amount to APIC. No shares are recorded as treasury stock at vesting as the shares of Quanta common stock associated with deferred equity awards are not issued. Upon settlement of the deferred equity awards and issuance of the associated Quanta common stock, the original accounting entry is reversed. The net amounts recorded to treasury stock related to the deferred compensation plans during the three months ended June 30, 2017 and 2016 were $0.2 million and $0.4 million , and the net amounts recorded to treasury stock related to the deferred compensation plans during the six months ended June 30, 2017 and 2016 were $3.4 million and $7.8 million . An aggregate of $17.7 million was included in treasury stock for notional amounts related to deferred compensation plans at June 30, 2017 . Retirement of Treasury Stock Effective December 1, 2016, Quanta retired 84.8 million shares of treasury stock. These retired shares were restored to the status of authorized and unissued shares as permitted by Delaware law. The retired stock had a carrying value of $1.95 billion . In accordance with Quanta’s policy, Quanta recorded the formal retirement of treasury stock by deducting the par value from common stock and the excess of cost over par value from APIC. Stock repurchases During the second quarter of 2017, Quanta’s board of directors approved a stock repurchase program that authorizes Quanta to purchase, from time to time through June 30, 2020, up to $300.0 million of its outstanding common stock (the 2017 Repurchase Program). Repurchases under the 2017 Repurchase Program can be made in open market and privately negotiated transactions. As of June 30, 2017 , Quanta had not repurchased any shares of its common stock under the 2017 Repurchase Program. During the third quarter of 2015, Quanta’s board of directors approved a stock repurchase program that authorized Quanta to purchase, from time to time through February 28, 2017, up to $1.25 billion of its outstanding common stock (the 2015 Repurchase Program). Repurchases under the 2015 Repurchase Program were made in open market and privately negotiated transactions, including pursuant to an accelerated share repurchase arrangement and an issuer repurchase plan. During 2015, Quanta repurchased 19.2 million shares of its common stock at a cost of $449.9 million in the open market under the 2015 Repurchase Program. During the third quarter of 2015, Quanta also entered into an accelerated share repurchase arrangement (the ASR) to repurchase $750.0 million of its common stock under the 2015 Repurchase Program. Under the terms of the ASR, Quanta paid $750.0 million to JPMorgan Chase Bank, National Association, London Branch (JPMorgan) and initially received 25.7 million shares of its common stock. The fair market value of these 25.7 million shares at the time of delivery was $600.0 million , and the repurchased shares and the related cost to acquire them were accounted for as an adjustment to the balance of treasury stock during the third quarter of 2015, reducing the weighted-average number of basic and diluted common shares used to calculate Quanta’s earnings per share. The $150.0 million remaining under the ASR was recorded as an adjustment to APIC during the third quarter of 2015 and was reclassified from APIC to treasury stock upon final settlement of the ASR on April 12, 2016 . At final settlement and based on the final volume-weighted average share price during the term of the ASR, minus a discount and subject to other adjustments pursuant to the terms and conditions of the ASR, Quanta received 9.4 million additional shares of its common stock from JPMorgan. The 2015 Repurchase Program ended on February 28, 2017, and Quanta repurchased a total of 54.3 million shares of its common stock at a cost of $1.20 billion under the 2015 Repurchase Program. Other than the shares received at settlement of the ASR in the second quarter of 2016, no common stock was repurchased in the six months ended June 30, 2017 or 2016 under the 2015 Repurchase Program. Other Under Delaware corporate law, treasury stock is not counted for quorum purposes or entitled to vote. Non-controlling Interests Quanta holds investments in several joint ventures that provide infrastructure services under specific customer contracts. Quanta has determined that certain of these joint ventures are VIEs, with Quanta providing the majority of the infrastructure services to the joint venture, which management believes most significantly influences the economic performance of the joint venture. Management has concluded that Quanta is the primary beneficiary of each of the joint ventures determined to be VIEs and has accounted for each on a consolidated basis. The other parties’ equity interests in these joint ventures have been accounted for as “Non-controlling interests” in the accompanying condensed consolidated balance sheets. Net income attributable to the other joint venture members in the amounts of $0.5 million and $0.2 million for the three months ended June 30, 2017 and 2016 and $0.7 million and $0.5 million for the six months ended June 30, 2017 and 2016 has been accounted for as a reduction of net income in deriving “Net income attributable to common stock” in the accompanying condensed consolidated statements of operations. The carrying value of the investments held by Quanta in all of its VIEs was $2.6 million and $3.3 million at June 30, 2017 and December 31, 2016 . The carrying value of investments held by the non-controlling interests in these variable interest entities at June 30, 2017 and December 31, 2016 was $2.6 million and $3.3 million . During the three months ended June 30, 2017 and 2016 , distributions to non-controlling interests were $0.4 million and none . During the six months ended June 30, 2017 and 2016 , distributions to non-controlling interests were $1.4 million and none . There were no other changes in equity as a result of transfers to/from the non-controlling interests during the six months ended June 30, 2017 or 2016 . See Note 10 for further disclosures related to Quanta’s joint venture arrangements.

Equity-Based Compensation

Equity-Based Compensation	6 Months Ended
	Jun. 30, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Equity-Based Compensation	EQUITY-BASED COMPENSATION: Stock Incentive Plans On May 19, 2011 , Quanta’s stockholders approved the 2011 Omnibus Equity Incentive Plan (the 2011 Plan). The 2011 Plan provides for the award of non-qualified stock options, incentive (qualified) stock options, stock appreciation rights, restricted stock, RSUs, stock bonus awards, performance compensation awards (including performance units and cash bonus awards) or any combination of the foregoing. The purpose of the 2011 Plan is to attract and retain key personnel and provide participants with additional performance incentives by increasing their proprietary interest in Quanta. Employees, directors, officers, consultants or advisors of Quanta or its affiliates are eligible to participate in the 2011 Plan, as are prospective employees, directors, officers, consultants or advisors of Quanta who have agreed to serve Quanta in those capacities. An aggregate of 11,750,000 shares of Quanta common stock may be issued pursuant to awards granted under the 2011 Plan. Quanta also has a Restricted Stock Unit Plan (the RSU Plan), pursuant to which RSUs may be awarded to certain employees and consultants of Quanta’s Canadian operations. The Quanta Services, Inc. 2007 Stock Incentive Plan (the 2007 Plan), which was adopted on May 24, 2007, and provided for awards of restricted stock, incentive stock options and non-qualified stock options to eligible employees, directors, and certain consultants and advisors terminated on May 24, 2017. The 2011 Plan and the RSU Plan, together with certain plans assumed by Quanta in acquisitions, are referred to as the Plans. Restricted Stock and RSUs to be Settled in Common Stock During each of the three months ended June 30, 2017 and 2016 , Quanta granted 0.1 million RSUs to be settled in common stock under the 2011 Plan with weighted average grant date fair values of $33.32 and $23.59 . During the six months ended June 30, 2017 and 2016 , Quanta granted 1.2 million and 1.8 million RSUs to be settled in common stock under the 2011 Plan with weighted average grant date fair values of $37.76 and $22.11 . The grant date fair value for awards of restricted stock and RSUs to be settled in common stock is based on the market value of Quanta common stock on the date of grant. RSUs to be settled in common stock are subject to forfeiture, restrictions on transfer and certain other conditions until vesting, which generally occurs in equal installments over a two -year or three -year period following the date of grant. Holders of RSUs to be settled in common stock are entitled to receive a cash dividend equivalent payment equal to any cash dividend payable on account of common shares. During each of the three months ended June 30, 2017 and 2016 , vesting activity consisted of 0.1 million shares of restricted stock and RSUs settled in common stock with an approximate fair value at the time of vesting of $3.8 million and $1.1 million . During the six months ended June 30, 2017 and 2016 , vesting activity consisted of 1.4 million and 1.3 million shares of restricted stock and RSUs settled in common stock with an approximate fair value at the time of vesting of $54.3 million and $26.4 million . During the three months ended June 30, 2017 and 2016 , Quanta recognized $10.1 million and $8.5 million in non-cash stock compensation expense related to restricted stock and RSUs to be settled in common stock. During the six months ended June 30, 2017 and 2016 , Quanta recognized $21.3 million and $21.7 million in non-cash stock compensation expense related to restricted stock and RSUs to be settled in common stock. As of June 30, 2017 , there was $49.2 million of total unrecognized compensation cost related to unvested RSUs to be settled in common stock granted to both employees and non-employees. This cost is expected to be recognized over a weighted average period of 1.89 years. Performance Units to be Settled in Common Stock Performance units awarded pursuant to the 2011 Plan provide for the issuance of shares of common stock upon vesting. These performance units cliff-vest at the end of a three -year performance period based on achievement of certain performance metrics established by Quanta’s compensation committee, including company performance goals and, with respect to certain awards, Quanta’s total shareholder return as compared to a predetermined group of peer companies. The final number of earned and vested performance units can range from 0% to 200% of the initial award based on the level of achievement of such goals, as determined by Quanta’s compensation committee. During the three months ended June 30, 2017 and 2016 , Quanta granted a nominal number and 0.1 million performance units to be settled in common stock under the 2011 Plan. The weighted average grant date fair value of performance units granted in the three months ended June 30, 2016 was $24.11 per unit. During each of the six months ended June 30, 2017 and 2016 , Quanta granted 0.3 million performance units to be settled in common stock under the 2011 Plan with a weighted average grant date fair value of $17.63 and $22.86 per unit. The grant date fair value for awards of performance units without market-based metrics was based on the market value of Quanta common stock on the date of grant applied to the total number of performance units that Quanta anticipates will vest. The grant date fair value for awards of performance units with market-based metrics, which were granted in the six months ended June 30, 2017 , was based on a fair value as determined by a Monte Carlo simulation using the following key inputs: Valuation date stock price based on the March 22, 2017 closing stock price $36.31 Expected volatility 36.00 % Risk-free interest rate 1.46 % Term in years 2.78 This fair value is expensed ratably over the three -year performance period and is adjusted for changes in the expected probability of achievement of the underlying goals and the resulting number of performance units anticipated to vest, so that the expense recognized is equivalent to the proportion of the three-year period that has expired multiplied by the fair value of the number of performance units anticipated to vest. During the three months ended June 30, 2017 and 2016 , Quanta recognized $1.4 million and $1.0 million in compensation expense associated with performance units to be settled in common stock. During the six months ended June 30, 2017 and 2016 , Quanta recognized $2.1 million and $1.5 million in compensation expense associated with performance units to be settled in common stock. During the three months ended June 30, 2017 and 2016 , no performance units vested, and no shares of common stock were issued in connection with performance units. During the six months ended June 30, 2017 and 2016 , 0.1 million and no performance units vested, and 0.1 million and no shares of common stock were issued in connection with performance units. The fair value of the 0.1 million performance units that vested during the six months ended June 30, 2017 was $4.3 million at the time of vesting RSUs to be Settled in Cash Certain RSUs granted by Quanta under the Plans are settled solely in cash. These cash-settled RSUs are intended to provide plan participants with cash performance incentives that are substantially equivalent to the risks and rewards of equity ownership in Quanta, typically vest in equal installments over a two -year or three -year period following the date of grant, and are subject to forfeiture under certain conditions, primarily termination of service. Additionally, subject to certain restrictions, Quanta’s non-employee directors may elect to cash settle a portion of their RSU awards, which generally vest upon conclusion of the director service year. For all RSUs settled in cash, the holders receive for each vested RSU an amount in cash equal to the fair market value of one share of Quanta common stock on the settlement date, as specified in the applicable award agreement. Compensation expense related to RSUs to be settled in cash was $1.2 million and $1.4 million for the three months ended June 30, 2017 and 2016 and $3.9 million and $2.9 million for the six months ended June 30, 2017 and 2016 . Such expense is recorded in selling, general and administrative expenses. RSUs that are anticipated to be settled in cash are not included in the calculation of earnings per share, and the estimated earned value of such RSUs is classified as a liability. Quanta paid $3.8 million and $2.4 million to settle liabilities related to cash-settled RSUs in the three months ended June 30, 2017 and 2016 and $6.1 million and $3.4 million to settle liabilities related to cash-settled RSUs in the six months ended June 30, 2017 and 2016 . Accrued liabilities for the estimated earned value of outstanding RSUs to be settled in cash were $2.9 million and $5.1 million at June 30, 2017 and December 31, 2016 .

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	COMMITMENTS AND CONTINGENCIES: Investments in Affiliates and Other Entities As described in Note 8, Quanta holds investments in certain joint ventures with third parties for the purpose of providing infrastructure services under certain customer contracts. Losses incurred by these joint ventures are generally shared ratably based on the percentage ownership of the joint venture members. However, each member of the joint venture typically is jointly and severally liable for all of the obligations of the joint venture under the contract with the customer, and therefore can be liable for full performance of the contract with the customer. In circumstances where Quanta’s participation in a joint venture qualifies as a general partnership, the joint venture partners are jointly and severally liable for all of the obligations of the joint venture, including obligations owed to the customer or any other person or entity. Quanta is not aware of circumstances that would lead to future claims against it for material amounts in connection with these joint and several liabilities. In the joint venture arrangements entered into by Quanta, typically each joint venture party indemnifies the other party for any liabilities incurred in excess of the liabilities such other party is obligated to bear under the respective joint venture agreement. It is possible, however, that Quanta could be required to pay or perform obligations in excess of its share if the other party to the joint venture failed or refused to pay or perform its share of the obligations. Quanta is not aware of circumstances that would lead to future claims against it for material amounts that would not be indemnified. During 2014, a limited partnership in which Quanta is a partner was selected for an engineering, procurement and construction (EPC) electric transmission project to construct approximately 500 kilometers of transmission line and two 500 kV substations. Quanta will provide turnkey EPC services for the entire project. As of June 30, 2017 , Quanta had made aggregate contributions to this unconsolidated affiliate of $26.7 million and had received $3.0 million as a return of capital. Also as of June 30, 2017 , Quanta had outstanding additional capital commitments associated with investments in an unconsolidated affiliate related to this project as follows (in thousands): Year Ending December 31 — Capital Commitments Remainder of 2017 (1) $ 34,953 2018 — 2019 24,444 Total capital commitments associated with investments in an unconsolidated affiliate related to an EPC electrical transmission project $ 59,397 (1) A return of capital from unconsolidated affiliates of approximately $56.3 million is anticipated in the fourth quarter of 2017 and is not included in these amounts. Additionally, as of June 30, 2017 , Quanta had outstanding capital commitments associated with investments in unconsolidated affiliates related to planned oil and gas infrastructure projects of $18.1 million , of which $0.4 million is expected to be paid in the third quarter of 2017 . The remaining $17.7 million of these capital commitments is anticipated to be paid by May 31, 2022 . As described in Note 2, Quanta formed a partnership with select infrastructure investors that provides $750.0 million of capital, including $60.0 million from Quanta, available to invest in certain of these infrastructure projects. Leases Quanta leases certain land, buildings and equipment under non-cancelable lease agreements, including related party leases. The terms of these agreements vary from lease to lease, including some with renewal options and escalation clauses. The following schedule shows the future minimum lease payments under these leases as of June 30, 2017 (in thousands): Operating Leases Year Ending December 31 — Remainder of 2017 $ 58,794 2018 83,916 2019 56,978 2020 34,264 2021 19,605 Thereafter 24,504 Total minimum lease payments $ 278,061 Rent expense related to operating leases was $67.8 million and $58.4 million for the three months ended June 30, 2017 and 2016 and $132.8 million and $114.8 million for the six months ended June 30, 2017 and 2016 . Quanta has guaranteed the residual value on certain of its equipment operating leases. Quanta has agreed to pay any difference between this residual value and the fair market value of the underlying asset at the date of termination of the leases. At June 30, 2017 , the maximum guaranteed residual value was $588.4 million . Quanta believes that no significant payments will be made as a result of the difference between the fair market value of the leased equipment and the guaranteed residual value. However, there can be no assurance that significant payments will not be required in the future. Committed Expenditures Quanta has capital commitments for the expansion of its vehicle fleet in order to accommodate manufacturer lead times on certain types of vehicles. As of June 30, 2017 , $19.0 million of production orders were issued with expected delivery dates in 2017 , and $1.4 million of production orders were issued with expected delivery dates in 2018 . Although Quanta has committed to purchase these vehicles at the time of their delivery, Quanta anticipates that these orders will be assigned to third party leasing companies and made available to Quanta under certain of its master equipment lease agreements, thereby releasing Quanta from its capital commitments. Legal Proceedings Quanta is from time to time party to various lawsuits, claims and other legal proceedings that arise in the ordinary course of business. These actions typically seek, among other things, compensation for alleged personal injury, breach of contract and/or property damages, employment-related damages, punitive damages, civil penalties or other losses, or injunctive or declaratory relief. With respect to all such lawsuits, claims and proceedings, Quanta records a reserve when it is probable that a liability has been incurred and the amount of loss can be reasonably estimated. In addition, Quanta discloses matters for which management believes a material loss is at least reasonably possible. Except as otherwise stated below, none of these proceedings, separately or in the aggregate, are expected to have a material adverse effect on Quanta’s consolidated financial position, results of operations or cash flows. In all instances, management has assessed the matter based on current information and made a judgment concerning its potential outcome, giving due consideration to the nature of the claim, the amount and nature of damages sought and the probability of success. Management’s judgment may prove materially inaccurate, and such judgment is made subject to the known uncertainties of litigation. Lorenzo Benton v. Telecom Network Specialists, Inc., et al. In June 2006, plaintiff Lorenzo Benton filed a class action complaint in the Superior Court of California, County of Los Angeles, alleging various wage and hour violations against Telecom Network Specialists (TNS), a former subsidiary of Quanta. Quanta retained liability associated with this matter pursuant to the terms of Quanta’s sale of TNS in December 2012. Benton seeks to represent a class of workers that includes all persons who worked on certain TNS projects, including individuals that TNS retained through numerous staffing agencies. The plaintiff class in this matter is seeking damages for unpaid wages, penalties associated with the failure to provide meal and rest periods and overtime wages, interest and attorneys’ fees. In September 2015, the trial court certified the class as to workers from the various staffing companies at issue. In January 2017, the trial court granted a summary judgment motion filed by the plaintiff class and found that TNS was a joint employer of the class members and that it failed to provide adequate meal and rest breaks and failed to pay overtime wages. Quanta believes this decision is not supported by controlling law and continues to contest liability in this matter. Additionally, in November 2007, TNS filed cross complaints for indemnity and breach of contract against the staffing agencies, which employed many of the individuals in question. In December 2012, the trial court heard cross-motions for summary judgment filed by TNS and the staffing agencies pertaining to TNS’s demand for indemnity. The court denied TNS’s motion and granted the motions filed by the staffing agencies; however, the California Appellate Court reversed the trial court’s decision in part and instructed the trial court to reconsider its ruling. In February 2017, the court denied a new motion for summary judgment filed by the staffing companies and stated that the staffing companies were liable to TNS for any damages owed to the class members that the staffing companies employed. The final amount of liability, if any, payable in connection with this matter remains the subject of pending litigation and will ultimately depend on various factors, including the outcome of Quanta’s appeal of the trial court’s ruling and the solvency of the staffing agencies. Based on review and analysis of the trial court’s rulings, Quanta does not believe, at this time, that it is probable this matter will result in a material loss. However, after review and consideration of a revised estimate of the potential liability for this matter during the second quarter of 2017, Quanta believes the range of reasonably possible loss could be up to approximately $16.5 million upon final resolution of this matter. For additional information regarding other pending legal proceedings, see Collective Bargaining Agreements in this Note 10. Concentrations of Credit Risk Quanta is subject to concentrations of credit risk related primarily to its cash and cash equivalents and net receivable position with customers, which includes amounts related to billed and unbilled accounts receivable and costs and estimated earnings in excess of billings on uncompleted contracts net of advanced billings with the same customer. Substantially all of Quanta’s cash and cash equivalents are managed by what it believes to be high credit quality financial institutions. In accordance with Quanta’s investment policies, these institutions are authorized to invest cash and cash equivalents in a diversified portfolio of what Quanta believes to be high quality cash and cash equivalent investments, which consist primarily of interest-bearing demand deposits, money market investments, money market mutual funds and investment grade commercial paper with original maturities of three months or less. Although Quanta does not currently believe the principal amount of these cash and cash equivalents is subject to any material risk of loss, changes in economic conditions could impact the interest income Quanta receives from these investments. In addition, Quanta grants credit under normal payment terms, generally without collateral, to its customers, which include electric power and oil and gas companies, governmental entities, general contractors, and builders, owners and managers of commercial and industrial properties located primarily in the United States, Canada and Australia. Consequently, Quanta is subject to potential credit risk related to changes in business and economic factors throughout the United States, Canada and Australia, which may be heightened as a result of uncertain economic and financial market conditions that have existed in recent years. However, Quanta generally has certain statutory lien rights with respect to services provided. Historically, some of Quanta’s customers have experienced significant financial difficulties, and others may experience financial difficulties in the future. These difficulties expose Quanta to increased risk related to collectability of billed and unbilled receivables and costs and estimated earnings in excess of billings on uncompleted contracts for services Quanta has performed. At June 30, 2017 and December 31, 2016 , one customer within Quanta’s Electric Power Infrastructure Services segment accounted for approximately 13% and 16% of Quanta’s consolidated net receivable position. Portions of these net receivable balances were related to invoicing challenges and billing delays on two electric transmission projects located in remote regions of northeastern Canada, which resulted from changed site conditions requiring extensive quality assurance documentation and administrative requirements. During the second quarter of 2017, Quanta and the customer reached a settlement and entered into a renegotiated contract, which eliminated the previous scheduling and billing issues and settled outstanding change orders. Additionally, one customer within Quanta’s Oil and Gas Infrastructure Services segment accounted for approximately 10% of Quanta’s consolidated net receivable position at June 30, 2017 . This same customer also accounted for approximately 10% of Quanta’s consolidated revenues during the three and six months ended June 30, 2017 . No other customers represented 10% or more of Quanta’s consolidated net receivable position as of June 30, 2017 or December 31, 2016 , and no other customers represented 10% or more of Quanta’s consolidated revenues for the three and six months ended June 30, 2017 or 2016 . Self-Insurance As discussed in Note 2, Quanta is insured for employer’s liability, workers’ compensation, auto liability, general liability and group health claims. As of June 30, 2017 and December 31, 2016 , the gross amount accrued for insurance claims totaled $238.1 million and $218.2 million , with $167.5 million and $162.0 million considered to be long-term and included in “Insurance and other non-current liabilities”. Related insurance recoveries/receivables as of June 30, 2017 and December 31, 2016 were $24.4 million and $8.7 million , of which $16.9 million and $0.4 million were included in “Prepaid expenses and other current assets” and $7.5 million and $8.3 million were included in “Other assets, net”. Letters of Credit Certain of Quanta’s vendors require letters of credit to ensure reimbursement for amounts they are disbursing on Quanta’s behalf, such as to beneficiaries under its self-funded insurance programs. In addition, from time to time, certain customers require Quanta to post letters of credit to ensure payment of subcontractors and vendors and guarantee performance under contracts. Such letters of credit are generally issued by a bank or similar financial institution, typically pursuant to Quanta’s credit facility. Each letter of credit commits the issuer to pay specified amounts to the holder of the letter of credit if the holder demonstrates that Quanta has failed to perform specified actions. If this were to occur, Quanta would be required to reimburse the issuer of the letter of credit. Depending on the circumstances of such a reimbursement, Quanta may also be required to record a charge to earnings for the reimbursement. Quanta does not believe that it is likely that any material claims will be made under a letter of credit in the foreseeable future. As of June 30, 2017 , Quanta had $324.7 million in outstanding letters of credit and bank guarantees under its credit facility securing its casualty insurance program and various contractual commitments. These are irrevocable stand-by letters of credit with maturities generally expiring at various times throughout 2017 and 2018 . Upon maturity, it is expected that the majority of the letters of credit related to the casualty insurance program will be renewed for subsequent one-year periods. Performance Bonds and Parent Guarantees In certain circumstances, Quanta is required to provide performance bonds in connection with its contractual commitments. Quanta has indemnified its sureties for any expenses paid out under these performance bonds. These performance bonds expire at various times ranging from mechanical completion of the related projects to a period extending beyond contract completion in certain circumstances, and as such a determination of maximum potential amounts outstanding requires the use of certain estimates and assumptions. Such amounts can also fluctuate from period to period based upon the mix and level of Quanta’s bonded operating activity. As of June 30, 2017 , the total amount of the outstanding performance bonds was estimated to be approximately $3.5 billion . Quanta’s estimated maximum exposure as it relates to the value of the performance bonds outstanding is lowered on each bonded project as the cost to complete is reduced, and each of its commitments under the performance bonds generally extinguishes concurrently with the expiration of its related contractual obligation. The estimated cost to complete these bonded projects was approximately $840 million as of June 30, 2017 . Additionally, from time to time, Quanta guarantees the obligations of its wholly owned subsidiaries, including obligations in connection with certain contracts with customers, lease obligations, joint venture arrangements and, in some states, contractors’ licenses. Quanta is not aware of any material obligations for performance or payment asserted against it under any of these guarantees. Employment Agreements Quanta has various employment agreements with certain executives and other employees, which provide for compensation and certain other benefits and for severance payments under certain circumstances. Certain employment agreements also contain clauses that become effective upon a change in control of Quanta, and Quanta may be obligated to pay certain amounts to such employees upon the occurrence of any of the defined change in control events. Collective Bargaining Agreements Some of Quanta’s operating units are parties to various collective bargaining agreements with unions that represent certain of their employees. The collective bargaining agreements expire at various times and have typically been renegotiated and renewed on terms similar to those in the expiring agreements. From time to time, Quanta is a party to grievance actions based on claims arising out of the collective bargaining agreements. The agreements require the operating units to pay specified wages, provide certain benefits to their union employees and contribute certain amounts to multiemployer pension plans and employee benefit trusts. Quanta’s multiemployer pension plan contribution rates generally are specified in the collective bargaining agreements (usually on an annual basis), and contributions are made to the plans on a “pay-as-you-go” basis based on its union employee payrolls. The location and number of union employees that Quanta employs at any given time and the plans in which they may participate vary depending on the projects Quanta has ongoing at any time and the need for union resources in connection with those projects. Therefore, Quanta is unable to accurately predict its union employee payroll and the amount of the resulting multiemployer pension plan contribution obligation for future periods. The Pension Protection Act of 2006 (PPA) also added special funding and operational rules generally applicable to plan years beginning after 2007 for multiemployer plans that are classified as “endangered,” “seriously endangered” or “critical” status based on multiple factors (including, for example, the plan’s funded percentage, cash flow position and whether it is projected to experience a minimum funding deficiency). Plans in these classifications must adopt measures to improve their funded status through a funding improvement or rehabilitation plan, as applicable, which may require additional contributions from employers (which may take the form of a surcharge on benefit contributions) and/or modifications to retiree benefits. Certain plans to which Quanta contributes or may contribute in the future are in “endangered,” “seriously endangered” or “critical” status. The amount of additional funds, if any, that Quanta may be obligated to contribute to these plans in the future cannot be estimated due to uncertainty of the future levels of work that require the specific use of union employees covered by these plans, as well as the future contribution levels and possible surcharges on contributions applicable to these plans. Quanta may be subject to additional liabilities imposed by law as a result of its participation in multiemployer defined benefit pension plans. For example, the Employee Retirement Income Security Act of 1974, as amended by the Multiemployer Pension Plan Amendments Act of 1980, imposes certain liabilities upon an employer who is a contributor to a multiemployer pension plan if the employer withdraws from the plan or the plan is terminated or experiences a mass withdrawal. These liabilities include an allocable share of the unfunded vested benefits in the plan for all plan participants, not merely the benefits payable to a contributing employer’s own retirees. As a result, participating employers may bear a higher proportion of liability for unfunded vested benefits if other participating employers cease to contribute or withdraw, with the reallocation of liability being more acute in cases when a withdrawn employer is insolvent or otherwise fails to pay its withdrawal liability. Other than as described below, Quanta is not aware of any material amounts of withdrawal liability that have been incurred as a result of a withdrawal by any of Quanta’s operating units from any multiemployer defined benefit pension plans. 2011 Central States Plan Withdrawal Liability. In the fourth quarter of 2011, certain Quanta subsidiaries withdrew from the Central States, Southeast and Southwest Areas Pension Plan (the Central States Plan). This withdrawal event was the result of an amendment to a collective bargaining agreement with the International Brotherhood of Teamsters (Teamsters) that eliminated certain employers’ obligations to contribute to the Central States Plan, which was then in critical status and significantly underfunded as to its vested benefit obligations. The amendment was negotiated by the Pipe Line Contractors Association (PLCA) on behalf of its members, which include certain Quanta subsidiaries. Because certain other Quanta subsidiaries continued participation in the Central States Plan into 2012, the Quanta subsidiaries’ withdrawals in 2011 effected only a partial withdrawal on behalf of Quanta for 2011. Quanta believed that the partial withdrawal was advantageous because it limited exposure to increased liability resulting from a future withdrawal event, at which point the Central States Plan could have been further underfunded. Quanta and other PLCA members now contribute to a different multiemployer pension plan on behalf of the affected Teamsters employees. While certain additional Quanta subsidiaries continued participation in the Central States Plan into 2012, Quanta believes that such subsidiaries withdrew from the Central States Plan in 2012, thereby effecting a complete withdrawal as of December 30, 2012 for all Quanta subsidiaries. In connection with the partial withdrawal in 2011, Quanta recorded a withdrawal liability of approximately $32.6 million in the fourth quarter of 2011 based on estimates received from the Central States Plan. The Central States Plan subsequently asserted that the withdrawal of the PLCA members, and thus Quanta’s partial withdrawal, was not effective in 2011. The PLCA and Quanta believed at that time that a legally effective withdrawal had occurred during the fourth quarter of 2011, and this issue was litigated in the federal district court for the Northern District of Illinois, Eastern Division. In September 2013, the district court ruled in favor of the Central States Plan, and that decision was appealed by the PLCA. In July 2014, the Central States Plan provided Quanta with a Notice and Demand claiming partial withdrawal liability in the amount of $39.6 million and requiring Quanta to make payments on this assessment while the dispute is ongoing. In September 2015, the United States Court of Appeals for the Seventh Circuit ruled in favor of the PLCA and reversed the district court’s previous ruling which had been in favor of the Central States Plan. Based on the outcome of the appeal, in January 2016, the Central States Plan issued a revised Notice and Demand claiming a partial withdrawal liability in the amount of $32.9 million . Separately, in December 2013, the Central States Plan filed lawsuits against two of Quanta’s other subsidiaries in connection with their withdrawal in 2012. In the first lawsuit, the Central States Plan alleged that the subsidiary elected to participate in the Central States Plan pursuant to the collective bargaining agreement under which it participated. Quanta argued that no such election was made and that any payments made to the Central States Plan were made in error. In July 2014, the parties reached an agreement to settle the lawsuit, and the court dismissed the case with prejudice. In the second lawsuit, the Central States Plan alleged that contributions made by the Quanta subsidiary to a new industry fund created after Quanta withdrew from the Central States Plan should have been made to the Central States Plan. This arguably would have extended the withdrawal date for this subsidiary to at least the end of 2013. Quanta disputed these allegations on the basis that it properly paid contributions to the new industry fund based on the terms of the collective bargaining agreement under which it participated and asserted that it terminated its obligation to contribute to the Central States Plan by the end of 2012. The parties both moved for summary judgment, and in March 2015, the court entered judgment in favor of Quanta. The Central States Plan filed a notice of appeal in April 2015, and in December 2015, the Central States Plan agreed to dismiss the appeal with prejudice. The ultimate liability associated with the complete withdrawal of Quanta’s subsidiaries from the Central States Plan will depend on various factors, including interpretations of the terms of the collective bargaining agreements under which the subsidiaries participated and whether exemptions from withdrawal liability applicable to construction industry employers will be available. In March 2014, the Central States Plan provided revised estimates indicating that the total withdrawal liability based on certain withdrawal scenarios from 2011 through 2014 could range between $40.1 million and $55.4 million , which Quanta believes to be the range of reasonably possible loss for this matter. Additionally, based on those estimates and allowing for the exclusion of amounts believed by management to have been improperly included in such estimates, Quanta recorded an adjustment to cost of services during the three months ended March 31, 2014 to increase the recognized withdrawal liability to an amount within the range communicated to Quanta by the Central States Plan. Given the unknown nature of some of the factors mentioned above, the final withdrawal liability cannot yet be determined with certainty. Accordingly, it is reasonably possible that the amount owed upon final resolution of these matters could be materially higher than the expense Quanta had recognized through June 30, 2017 . Although Quanta disputes the total liability owed to the Central States Plan, it continues to make monthly payments according to the terms of the January 2016 Notice and Demand while the parties determine the final withdrawal liability. As of June 30, 2017 , Quanta had made payments totaling $20.7 million toward the withdrawal liability assessment. 2013 Central States Plan Withdrawal Liability. On October 9, 2013, Quanta acquired a company that experienced a complete withdrawal from the Central States Plan prior to the date of acquisition. Prior to the acquisition, the Central States Plan issued a Notice and Demand to the acquired company claiming a withdrawal liability in the total amount of $6.9 million and requiring payments to be made on this assessment while the dispute is ongoing. In connection with the acquisition, Quanta recorded an initial liability of $4.8 million related to this withdrawal liability, and a portion of the purchase price for the acquired company was deposited into an escrow account to fund any withdrawal obligation in excess of the initial liability recorded. In January 2016, the Central States Plan issued a revised Notice and Demand claiming a withdrawal liability in the amount of $4.8 million . Although Quanta continues to dispute the total liability owed to the Central States Plan, it continues to make monthly payments according to the terms of this revised Notice and Demand while the parties determine the final withdrawal liability. As of June 30, 2017 , payments totaling $3.9 million had been made toward the withdrawal liability assessment. The final amount of withdrawal liability payable in connection with this matter remains the subject of a pending arbitration proceeding and will ultimately depend on various factors, including the outcome of the PLCA litigation described above. However, the acquired company’s withdrawal from the Central States Plan is not expected to have a material impact on Quanta’s financial condition, results of operations or cash flows. Indemnities Quanta generally indemnifies its customers for the services it provides under its contracts, as well as other specified liabilities, which may subject Quanta to indemnity claims and liabilities and related litigation. Additionally, in connection with certain acquisitions and dispositions, Quanta has indemnified various parties against specified liabilities that those parties might incur in the future. The indemnities under acquisition or disposition agreements are usually contingent upon the other party incurring liabilities that reach specified thresholds. As of June 30, 2017 , except as otherwise set forth above in Legal Proceedings , Quanta does not believe any material liabilities for claims exist against it in connection with any of these indemnity obligations. In the normal course of Quanta’s acquisition transactions, Quanta obtains rights to indemnification from the sellers or former owners of acquired companies for certain risks, liabilities and obligations arising from their prior operations, such as performance, operational, safety, workforce or tax issues, some of which Quanta may not have discovered during due diligence. However, the indemnities may not cover all of Quanta’s exposure for such pre-acquisition matters, and the indemnitors may be unwilling or unable to pay the amounts owed to Quanta. Accordingly, Quanta may incur expenses for which it is not reimbursed. Quanta is currently in the process of determining certain pre-acquisition obligations associated with non-U.S. payroll taxes that may be due from a business acquired by Quanta in 2013. As of June 30, 2017 , Quanta had recorded $11.4 million as its estimate of the pre-acquisition tax obligations and a corresponding indemnification asset, as management expects to recover from the indemnity counterparties any amounts that Quanta may be required to pay in connection with any such obligations.

Segment Information

Segment Information	6 Months Ended
	Jun. 30, 2017
Segment Reporting [Abstract]
Segment Information	SEGMENT INFORMATION: Quanta presents its operations under two reportable segments: (1) Electric Power Infrastructure Services and (2) Oil and Gas Infrastructure Services. This structure is generally based on the broad end-user markets for Quanta’s services. See Note 1 for additional information regarding Quanta’s reportable segments. Quanta’s segment results are derived from the types of services provided across its operating units in each of the end user markets described above. Quanta’s entrepreneurial business model allows each of its operating units to serve the same or similar customers and to provide a range of services across end user markets. Quanta’s operating units are organized into one of two internal divisions, namely, the Electric Power Infrastructure Services Division and the Oil and Gas Infrastructure Services Division. These internal divisions are closely aligned with the reportable segments described above based on their operating units’ predominant type of work. Reportable segment information, including revenues and operating income by type of work, is gathered from each operating unit for the purpose of evaluating segment performance in support of Quanta’s market strategies. These classifications of Quanta’s operating unit revenues by type of work for segment reporting purposes can at times require judgment on the part of management. Quanta’s operating units may perform joint infrastructure service projects for customers in multiple industries, deliver multiple types of network services under a single customer contract or provide service across industries. For example, Quanta performs joint trenching projects to install distribution lines for electric power and natural gas customers. In addition, Quanta’s integrated operations and common administrative support at each of its operating units require that certain allocations of shared and indirect costs, such as facility costs and indirect operating expenses, including depreciation and general and administrative costs, be made to determine operating segment profitability. Corporate costs, such as payroll and benefits, employee travel expenses, facility costs, professional fees, acquisition costs and amortization related to intangible assets are not allocated. Summarized financial information for Quanta’s reportable segments is presented in the following table (in thousands): Three Months Ended Six Months Ended June 30, June 30, 2017 2016 2017 2016 Revenues: Electric Power Infrastructure Services $ 1,300,729 $ 1,159,087 $ 2,520,231 $ 2,346,089 Oil and Gas Infrastructure Services 899,645 633,343 1,858,313 1,160,078 Consolidated $ 2,200,374 $ 1,792,430 $ 4,378,544 $ 3,506,167 Operating income (loss) : Electric Power Infrastructure Services $ 113,043 $ 75,934 $ 212,715 $ 163,258 Oil and Gas Infrastructure Services 67,751 11,899 106,568 17,740 Corporate and non-allocated costs (71,003 ) (52,364 ) (134,418 ) (108,235 ) Consolidated $ 109,791 $ 35,469 $ 184,865 $ 72,763 Depreciation: Electric Power Infrastructure Services $ 22,150 $ 22,937 $ 44,236 $ 45,882 Oil and Gas Infrastructure Services 18,134 17,254 35,498 33,055 Corporate and non-allocated costs 4,366 2,568 7,609 4,992 Consolidated $ 44,650 $ 42,759 $ 87,343 $ 83,929 Separate measures of Quanta’s assets and cash flows by reportable segment, including capital expenditures, are not produced or utilized by management to evaluate segment performance. Quanta’s fixed assets, which are held at the operating unit level, include operating machinery, equipment and vehicles, as well as office equipment, buildings and leasehold improvements, and are used on an interchangeable basis across its reportable segments. As such, for reporting purposes, total depreciation expense is allocated each quarter among Quanta’s reportable segments based on the ratio of each reportable segment’s revenue contribution to consolidated revenues. Foreign Operations During the three months ended June 30, 2017 and 2016 , Quanta derived $524.5 million and $335.6 million of its revenues from foreign operations. During the six months ended June 30, 2017 and 2016 , Quanta derived $1.18 billion and $688.0 million of its revenues from foreign operations. Of Quanta’s foreign revenues, 80% and 78% were earned in Canada during the three months ended June 30, 2017 and 2016 and 82% and 73% were earned in Canada during the six months ended June 30, 2017 and 2016 . In addition, Quanta held property and equipment of $331.6 million and $320.7 million in foreign countries, primarily Canada, as of June 30, 2017 and December 31, 2016 .

Supplemental Cash Flow Informat

Supplemental Cash Flow Information	6 Months Ended
	Jun. 30, 2017
Supplemental Cash Flow Elements [Abstract]
Supplemental Cash Flow Information	SUPPLEMENTAL CASH FLOW INFORMATION: The net effect of changes in operating assets and liabilities, net of non-cash transactions, on cash flows from operating activities of continuing operations is as follows (in thousands): Three Months Ended Six Months Ended June 30, June 30, 2017 2016 2017 2016 Accounts and notes receivable $ (31,605 ) $ 105,399 $ (126,443 ) $ 264,394 Costs and estimated earnings in excess of billings on uncompleted contracts (67,270 ) (82,456 ) (147,980 ) (134,923 ) Inventories (3,529 ) (2,256 ) (4,798 ) 2,281 Prepaid expenses and other current assets (29,355 ) (13,513 ) (33,637 ) (11,687 ) Accounts payable and accrued expenses and other non-current liabilities (55,848 ) 33,968 13,641 10,324 Billings in excess of costs and estimated earnings on uncompleted contracts 48,020 (48,465 ) 36,206 (12,527 ) Other, net 12,624 3,875 18,842 (999 ) Net change in operating assets and liabilities, net of non-cash transactions $ (126,963 ) $ (3,448 ) $ (244,169 ) $ 116,863 Additional supplemental cash flow information is as follows (in thousands): Three Months Ended Six Months Ended June 30, June 30, 2017 2016 2017 2016 Cash (paid) received during the period for — Interest paid related to continuing operations $ (4,044 ) $ (3,066 ) $ (7,506 ) $ (5,507 ) Income taxes paid related to continuing operations $ (93,279 ) $ (27,038 ) $ (101,496 ) $ (33,524 ) Income taxes paid related to discontinued operations $ — $ (437 ) $ — $ (6,080 ) Income tax refunds related to continuing operations $ 463 $ 785 $ 2,669 $ 1,679 During the three months ended June 30, 2017 , Quanta entered into a non-cash transaction whereby Quanta accepted title to a marine vessel in satisfaction and discharge of a $7.1 million note receivable.

Subsequent Event

Subsequent Event	6 Months Ended
	Jun. 30, 2017
Subsequent Events [Abstract]
Subsequent Event	SUBSEQUENT EVENT: Acquisition On July 20, 2017, Quanta acquired Stronghold, Ltd. and Stronghold Specialty, Ltd. (collectively Stronghold), a specialized services business located in the United States that provides high pressure and critical path solutions to the downstream and midstream energy markets. The aggregate consideration paid at closing for this acquisition was $360.0 million in cash and 2,693,680 shares of Quanta common stock, which had a fair value of approximately $90.0 million at the date of acquisition. Additionally, the acquisition includes the potential payment of up to approximately $100.0 million of contingent consideration, payable if the acquired business achieves certain financial targets. The results of the acquired business will be reflected in Quanta’s Oil and Gas Infrastructure Services segment and included in Quanta’s consolidated financial statements beginning on the date of acquisition. Due to the recent closing of this acquisition, certain financial information related to this acquisition, including the fair value of total consideration transferred or estimated to be transferred, is not yet finalized.

Summary of Significant Accoun21

Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2017
Accounting Policies [Abstract]
Principles of Consolidation	Principles of Consolidation The condensed consolidated financial statements of Quanta include the accounts of Quanta Services, Inc. and its wholly owned subsidiaries, which are also referred to as its operating units. The condensed consolidated financial statements also include the accounts of certain of Quanta’s investments in joint ventures, which are either consolidated or proportionately consolidated, as discussed in the following summary of significant accounting policies. Investments in affiliated entities in which Quanta does not have a controlling financial interest, but over which Quanta has significant influence, usually because Quanta holds a voting interest of between 20% and 50%, are accounted for using the equity method. All significant intercompany accounts and transactions have been eliminated in consolidation. Unless the context requires otherwise, references to Quanta include Quanta Services, Inc. and its consolidated subsidiaries.
Interim Condensed Consolidated Financial Information	Interim Condensed Consolidated Financial Information These unaudited condensed consolidated financial statements have been prepared pursuant to the rules of the U.S. Securities and Exchange Commission (SEC). Certain information and footnote disclosures, normally included in annual financial statements prepared in accordance with accounting principles generally accepted in the United States (US GAAP), have been condensed or omitted pursuant to those rules and regulations. Quanta believes that the disclosures made are adequate to make the information presented not misleading. In the opinion of management, all adjustments, consisting only of normal recurring adjustments, necessary to fairly state the financial position, results of operations, comprehensive income and cash flows with respect to the interim condensed consolidated financial statements have been included. The results of operations and comprehensive income for the interim periods are not necessarily indicative of the results for the entire fiscal year. The results of Quanta have historically been subject to significant seasonal fluctuations. Quanta recommends that these unaudited condensed consolidated financial statements be read in conjunction with the audited consolidated financial statements and notes thereto of Quanta and its consolidated subsidiaries included in Quanta’s Annual Report on Form 10-K for the year ended December 31, 2016 , which was filed with the SEC on March 1, 2017 .
Reclassifications	Reclassifications Quanta reclassified certain prior period amounts related to stock-based compensation on the condensed consolidated statements of cash flows to conform to the current period presentation under a recently adopted accounting update. Additionally, certain reclassifications have been made to the prior year’s condensed consolidated statements of operations to conform to classifications in the current year.
Use of Estimates and Assumptions	Use of Estimates and Assumptions The preparation of financial statements in conformity with US GAAP requires the use of estimates and assumptions by management in determining the reported amounts of assets and liabilities, disclosures of contingent assets and liabilities known to exist as of the date the financial statements are published, and the reported amounts of revenues and expenses recognized during the periods presented. Quanta reviews all significant estimates affecting its consolidated financial statements on a recurring basis and records the effect of any necessary adjustments prior to their publication. Judgments and estimates are based on Quanta’s beliefs and assumptions derived from information available at the time such judgments and estimates are made. Uncertainties with respect to such estimates and assumptions are inherent in the preparation of financial statements. Estimates are primarily used in Quanta’s assessment of the allowance for doubtful accounts, valuation of inventory, useful lives of assets, fair value assumptions in analyzing goodwill, other intangibles and long-lived asset impairments, equity and other investments, loan receivables, purchase price allocations, liabilities for self-insured and other claims and guarantees, multiemployer pension plan withdrawal liabilities, revenue recognition for construction contracts inclusive of contractual change orders and claims, share-based compensation, operating results of reportable segments, as well as the provision for income taxes and the calculation of uncertain tax positions.
Cash and Cash Equivalents	Cash and Cash Equivalents Quanta had cash and cash equivalents of $99.6 million and $112.2 million as of June 30, 2017 and December 31, 2016 . Cash consisting of interest-bearing demand deposits is carried at cost, which approximates fair value. Quanta considers all highly liquid investments with an original maturity of three months or less at the time of purchase to be cash equivalents, which are carried at fair value. At June 30, 2017 and December 31, 2016 , cash equivalents were $8.4 million and $8.8 million , and consisted primarily of money market investments and money market mutual funds and are discussed further in Fair Value Measurements below. As of June 30, 2017 and December 31, 2016 , cash and cash equivalents held in domestic bank accounts were $31.4 million and $19.5 million , and cash and cash equivalents held in foreign bank accounts were $68.2 million and $92.7 million . As of June 30, 2017 and December 31, 2016 , cash and cash equivalents held by Quanta’s investments in joint ventures, which are either consolidated or proportionately consolidated, were $13.4 million and $11.5 million , of which $10.5 million and $10.0 million related to domestic joint ventures. Cash and cash equivalents held by the joint ventures are available to support joint venture operations , but Quanta cannot utilize those assets to support its other operations. Quanta generally has no right to the joint ventures’ cash and cash equivalents other than participating in distributions and in the event of dissolution.
Current and Long-Term Accounts and Notes Receivable and Allowance for Doubtful Accounts	Current and Long-Term Accounts and Notes Receivable and Allowance for Doubtful Accounts Quanta provides an allowance for doubtful accounts when collection of an account or note receivable is considered doubtful, and receivables are written off against the allowance when deemed uncollectible. Inherent in the assessment of the allowance for doubtful accounts are certain judgments and estimates regarding, among other factors, the customer’s access to capital, the customer’s willingness or ability to pay, general economic and market conditions, the ongoing relationship with the customer and uncertainties related to the resolution of disputed matters. Quanta considers accounts receivable delinquent after 30 days but does not generally include delinquent accounts in its analysis of the allowance for doubtful accounts unless the accounts receivable have been outstanding for at least 90 days. In addition to balances that have been outstanding for 90 days or more, Quanta also includes accounts receivable balances that relate to customers in bankruptcy or with other known difficulties in its analysis of the allowance for doubtful accounts. Material changes in customers’ business or cash flows, which may be impacted by negative economic and market conditions, could affect Quanta’s ability to collect amounts due from them. As of June 30, 2017 and December 31, 2016 , Quanta had allowances for doubtful accounts on current receivables of $5.3 million and $2.8 million . Long-term accounts receivable are included within other assets. Should customers experience financial difficulties or file for bankruptcy, or should anticipated recoveries relating to receivables in existing bankruptcies or other workout situations fail to materialize, Quanta could experience reduced cash flows and losses in excess of current allowances provided. The balances billed but not paid by customers pursuant to retainage provisions in certain contracts are generally due upon completion of the contracts and acceptance by the customer. Based on Quanta’s experience with similar contracts in recent years, the majority of the retainage balances at each balance sheet date are expected to be collected within the next twelve months. Current retainage balances as of June 30, 2017 and December 31, 2016 were $239.8 million and $231.0 million and were included in “Accounts receivable“. Retainage balances with settlement dates beyond the next twelve months were included in “Other assets, net”, and as of June 30, 2017 and December 31, 2016 were $31.0 million and $5.2 million . Within accounts receivable, Quanta recognizes unbilled receivables in circumstances such as when revenues have been earned and recorded but the amount cannot be billed under the terms of the contract until a later date; costs have been incurred but are yet to be billed under cost-reimbursement type contracts; or amounts arise from routine lags in billing (for example, work completed one month but not billed until the next month). These balances do not include revenues accrued for work performed under fixed-price contracts as these amounts are recorded as costs and estimated earnings in excess of billings on uncompleted contracts. At June 30, 2017 and December 31, 2016 , the balances of unbilled receivables included in accounts receivable were $247.4 million and $206.8 million .
Goodwill and Other Intangibles	Goodwill and Other Intangibles Quanta has recorded goodwill in connection with its historical acquisitions of companies. Upon acquisition, these companies were either combined into one of Quanta’s existing operating units or managed on a stand-alone basis as an individual operating unit. Goodwill recorded in connection with these acquisitions is subject to an annual assessment for impairment, which Quanta performs at the operating unit level for each operating unit that carries a balance of goodwill. Each of Quanta’s operating units is organized into one of two internal divisions: the Electric Power Infrastructure Services Division and the Oil and Gas Infrastructure Services Division. As most of the companies acquired by Quanta provide multiple types of services for multiple types of customers, these divisional designations are based on the predominant type of work performed by each operating unit at the point in time the divisional designation is made. Goodwill is required to be measured for impairment at the reporting unit level, which represents the operating segment level or one level below the operating segment level for which discrete financial information is available. Quanta has determined that its individual operating units represent its reporting units for the purpose of assessing goodwill impairments. Quanta has the option to first assess qualitative factors to determine whether it is necessary to perform the two-step fair value-based impairment test described below. If Quanta believes that, as a result of its qualitative assessment, it is more likely than not that the fair value of a reporting unit is less than its carrying amount, the quantitative impairment test is required. Quanta can choose to perform the qualitative assessment on none, some or all of its reporting units. Quanta can also bypass the qualitative assessment for any reporting unit in any period and proceed directly to step one of the impairment test, and then resume the qualitative assessment in any subsequent period. Qualitative indicators including deterioration in macroeconomic conditions, declining financial performance, or a sustained decrease in share price, among other things, may trigger the need for annual or interim impairment testing of goodwill associated with one or all of the reporting units. Quanta’s goodwill impairment assessment is performed at year-end, or more frequently if events or circumstances arise which indicate that goodwill may be impaired. For instance, a decrease in Quanta’s market capitalization below book value, a significant change in business climate or loss of a significant customer, as well as the qualitative indicators referenced above, may trigger the need for interim impairment testing of goodwill for one or all of its reporting units. The first step of the two-step fair value based test involves comparing the fair value of each of Quanta’s reporting units with its carrying value, including goodwill. If the carrying value of the reporting unit exceeds its fair value, the second step is performed. The second step compares the carrying amount of the reporting unit’s goodwill to the implied fair value of its goodwill. If the implied fair value of goodwill is less than the carrying amount, an impairment loss would be recorded as a reduction to goodwill with a corresponding charge to operating expense. Quanta determines the fair value of its reporting units using a weighted combination of the discounted cash flow, market multiple and market capitalization valuation approaches, with heavier weighting on the discounted cash flow method, as in management’s opinion, this method currently results in the most accurate calculation of a reporting unit’s fair value. Determining the fair value of a reporting unit requires judgment and the use of significant estimates and assumptions. Such estimates and assumptions include, among others, revenue growth rates, operating margins, discount rates, weighted average costs of capital and future market conditions. Quanta believes the estimates and assumptions used in its impairment assessments are reasonable and based on available market information, but variations in any of the assumptions could result in materially different calculations of fair value and determinations of whether or not an impairment is indicated. Under the discounted cash flow method, Quanta determines fair value based on the estimated future cash flows of each reporting unit, discounted to present value using risk-adjusted industry discount rates, which reflect the overall level of inherent risk of a reporting unit and the rate of return an outside investor would expect to earn. Cash flow projections are derived from budgeted amounts and operating forecasts (typically a one-year model) plus an estimate of later period cash flows, all of which are evaluated by management. Subsequent period cash flows are developed for each reporting unit using growth rates that management believes are reasonably likely to occur, along with a terminal value derived from the reporting unit’s earnings before interest, taxes, depreciation and amortization (EBITDA). The EBITDA multiples for each reporting unit are based on trailing twelve-month comparable industry data. Under the market multiple and market capitalization approaches, Quanta determines the estimated fair value of each of its reporting units by applying transaction multiples to each reporting unit’s projected EBITDA and then averaging that estimate with similar historical calculations using either a one, two or three year average. For the market capitalization approach, Quanta adds a reasonable control premium, which is estimated as the premium that would be received in a sale of the reporting unit in an orderly transaction between market participants. For recently acquired reporting units, a step one impairment test may indicate an implied fair value that is substantially similar to the reporting unit’s carrying value. Such similarities in value are generally an indication that management’s estimates of future cash flows associated with the recently acquired reporting unit remain relatively consistent with the assumptions that were used to derive its initial fair value. During the fourth quarter of 2016 , a two-step fair-value based goodwill impairment analysis was performed for each of Quanta’s reporting units, and no reporting units were evaluated solely on a qualitative basis. Step one of the analysis indicated that the implied fair value of each of Quanta’s reporting units, other than recently acquired reporting units and the reporting units that recorded goodwill impairment charges in 2015, was substantially in excess of its carrying value. As discussed generally above, when evaluating the 2016 step one impairment test results, management considered many factors in determining whether or not an impairment of goodwill for any reporting unit was reasonably likely to occur in future periods, including future market conditions and the economic environment in which Quanta’s reporting units were operating. Additionally, management considered the sensitivity of its fair value estimates to changes in certain valuation assumptions. After taking into account a 10% decrease in the fair value of each of Quanta’s reporting units, two reporting units within Quanta’s Oil and Gas Infrastructure Division had fair values below their respective carrying values. Quanta recorded asset impairment charges for these reporting units in 2015. The fair values determined in 2016 for these reporting units were consistent with the fair values determined in 2015 and approximated their current carrying values, and therefore no impairment was required. Circumstances such as market declines, unfavorable economic conditions, loss of a major customer or other factors could increase the risk of impairment of goodwill for these reporting units in future periods. If an operating unit experiences prolonged periods of declining revenues, operating margins or both, it may be at risk of failing step one of the goodwill impairment test. Certain operating units have experienced declines over the short-term due to challenging macroeconomic conditions in certain geographic areas and low oil and natural gas prices, which have negatively impacted customer spending and resulted in project cancellations and delays. Additionally, customer capital spending has been constrained as a result of an increasingly complex regulatory and permitting environment. Certain operating units within Quanta’s Oil and Gas Infrastructure Services Division that primarily operate within the midstream and smaller-scale transmission market have continued to be negatively impacted by these factors. Goodwill and intangible assets associated with the operating units within Quanta’s Oil and Gas Infrastructure Services Division that have been significantly impacted by the factors mentioned above were $70.7 million and $11.5 million at June 30, 2017 . Quanta monitors these conditions and others to determine if it is necessary to perform step one of the fair-value based impairment test for one or more operating units prior to the annual impairment assessment. No interim impairment charges were recorded during the six months ended June 30, 2017 . Although Quanta is not aware of circumstances that would lead to a goodwill impairment at a reporting unit currently, circumstances such as a continued market decline, the loss of a major customer or other factors could impact the valuation of goodwill in the future. Quanta’s intangible assets include customer relationships, backlog, trade names, non-compete agreements, patented rights and developed technology, all subject to amortization. The value of customer relationships is estimated as of the date a business is acquired based on the value-in-use concept utilizing the income approach, specifically the excess earnings method. This analysis consists of discounting to present value the projected cash flows attributable to the customer relationships, with consideration given to customer contract renewals and estimated customer attrition rates, the importance of existing customer relationships to Quanta’s business plan, income taxes and required rates of return. Quanta values backlog for acquired businesses as of the acquisition date based upon the contractual nature of the backlog within each service line, discounted to present value. The value of trade names is estimated using the relief-from-royalty method of the income approach. This approach is based on the assumption that in lieu of ownership, a company would be willing to pay a royalty for use of the trade name. Quanta amortizes intangible assets based upon the estimated consumption of their economic benefits, or on a straight-line basis if the pattern of economic benefit cannot otherwise be reliably estimated. Intangible assets subject to amortization are reviewed for impairment and are tested for recoverability whenever events or changes in circumstances indicate that the carrying amount may not be recoverable. For instance, a significant change in business climate or a loss of a significant customer, among other things, may trigger the need for interim impairment testing of intangible assets. An impairment loss would be recognized if the carrying amount of an intangible asset is not recoverable and its carrying amount exceeds its fair value.
Investments in Affiliates and Other Entities	Investments in Affiliates and Other Entities In the normal course of business, Quanta enters into various types of investment arrangements, each having unique terms and conditions. These investments may include equity interests held by Quanta in business entities, including general or limited partnerships, contractual joint ventures, or other forms of equity or profit participation. These investments may also include Quanta’s participation in different financing structures such as the extension of loans to project specific entities, the acquisition of convertible notes issued by project specific entities, or other strategic financing arrangements. Quanta also enters into strategic partnerships with customers and infrastructure investors to provide fully integrated infrastructure services on certain projects, including planning and feasibility analyses, engineering, design, procurement, construction financing, and investment and project operation and maintenance. These projects include public-private partnerships, private infrastructure projects and concessions, along with build, own, operate and transfer and build to suit arrangements. As part of this strategy, Quanta formed a partnership with select infrastructure investors that provides $750.0 million of capital, including $60.0 million from Quanta, available to invest in certain of these infrastructure projects. Wholly owned subsidiaries of Quanta serve as the general partner of this partnership and as a separately operating registered investment adviser that manages the invested capital. Quanta determines whether such investments involve a variable interest entity (VIE) based on the characteristics of the subject entity. If the entity is determined to be a VIE, then management determines if Quanta is the primary beneficiary of the entity and whether or not consolidation of the VIE is required. The primary beneficiary consolidating the VIE must normally have both (i) the power to direct the activities that most significantly affect the VIE’s economic performance and (ii) the obligation to absorb significant losses of, or the right to receive significant benefits from, the VIE. When Quanta is deemed to be the primary beneficiary, the VIE is consolidated and the other party’s equity interest in the VIE is accounted for as a non-controlling interest. In cases where Quanta determines that it has an undivided interest in the assets, liabilities, revenues and profits of an unincorporated VIE (e.g., a general partnership interest), such amounts are consolidated on a basis proportional to Quanta’s ownership interest in the unincorporated entity. Investments in entities of which Quanta is not the primary beneficiary, but over which Quanta has the ability to exercise significant influence, are accounted for using the equity method of accounting. Quanta’s share of net income or losses from unconsolidated equity investments is reported as equity in earnings (losses) of unconsolidated affiliates, which is included in “Other income (expense)” in the condensed consolidated statements of operations. Equity investments are reviewed for impairment by assessing whether any decline in the fair value of the investment below the carrying value is other than temporary. In making this determination, factors such as the ability to recover the carrying amount of the investment and the inability of the investee to sustain an earnings capacity are evaluated in determining whether a loss in value should be recognized. Any impairment losses related to investments would be recognized in equity in earnings (losses) of unconsolidated affiliates. Equity method investments are carried at original cost and are included in “Other assets, net” in the condensed consolidated balance sheets and are adjusted for Quanta’s proportionate share of the investees’ income, losses and distributions. Under the investment structure described above, Quanta has a minority ownership interest in a limited partnership that was selected during 2014 to build, own and operate a new electric transmission line and two substations in Alberta, Canada. The limited partnership contracted with a Quanta subsidiary to perform the engineering, procurement and construction (EPC) services for the project, and the Quanta subsidiary recognizes revenue and related cost of services as performance progresses on the project. However, due to Quanta’s ownership interest, a proportional amount of the EPC profit is deferred until the electric transmission line and related substations are constructed and ownership of the assets is deemed to be transferred to the third party customer. The profit deferral has been recorded as a decrease to the equity method investment included in “Other assets, net” in the accompanying condensed consolidated balance sheets and as a component of equity in earnings (losses) of unconsolidated affiliates, which is included in “Other income (expense)” in the condensed consolidated statements of operations.
Revenue Recognition	Revenue Recognition Quanta provides its services pursuant to master service agreements, repair and maintenance contracts and fixed price and non-fixed price installation contracts. Pricing under these contracts may be competitive unit price, cost-plus/hourly (or time and materials basis) or fixed price (or lump sum basis), and the final terms and prices of these contracts are frequently negotiated with the customer. Under unit-based contracts, the utilization of an output-based measurement is appropriate for revenue recognition, and Quanta recognizes revenue as units are completed based on pricing established with the customer for each delivered unit, which best reflects the pattern in which the obligation to the customer is fulfilled. Under cost-plus/hourly and time and materials type contracts, Quanta recognizes revenue on an input basis, as labor hours are incurred and services are performed. Revenues from fixed price contracts are recognized using the percentage-of-completion method, measured by the percentage of costs incurred to date to total estimated costs for each contract. Such contracts provide that the customer accept completion of progress to date and compensate Quanta for services rendered, which may be measured in terms of units installed, hours expended, costs incurred to date compared to total estimated contract costs or some other measure of progress. Contract costs include all direct materials, labor and subcontract costs and those indirect costs related to contract performance, such as indirect labor, supplies, tools, repairs and depreciation costs. Much of the material associated with Quanta’s work is owner-furnished and is therefore not included in contract revenues and costs. The cost estimation process is based on professional knowledge and experience of Quanta’s engineers, project managers and financial professionals. Changes in job performance, job conditions and final contract settlements are factors that influence management’s assessment of contract value and estimated costs, and as a result, the profit recognized. Actual revenues and project costs can vary, sometimes substantially, from previous estimates due to changes in a variety of factors including unforeseen circumstances not included in Quanta’s cost estimates or covered by its contracts for which it cannot obtain adequate compensation, including concealed or unknown environmental conditions; changes in the cost of equipment, commodities, materials or labor; unanticipated costs or claims due to customer-caused delays, customer failure to provide required materials or equipment, errors in engineering, specifications or designs, project modifications, or contract termination and Quanta’s inability to obtain reimbursement for such costs or recover on such claims; weather conditions; and quality issues requiring rework or replacement. These factors, along with other risks inherent in performing fixed price contracts may cause actual revenues and gross profits for a project to differ from previous estimates and could result in reduced profitability or losses on projects. Changes in these factors may result in revisions to costs and income, and their effects are recognized in the period in which the revisions are determined. These factors are routinely evaluated on a project-by-project basis throughout the project term, and the impact of corresponding revisions in management’s estimates of contract value, contract cost and contract profit are recorded as necessary in the period in which the revisions are determined. Provisions for losses on uncompleted contracts are made in the period in which such losses are determined to be probable and the amount can be reasonably estimated. Quanta’s operating results for the three months ended June 30, 2017 were positively impacted by 10.2% as a result of aggregate changes in contract estimates related to projects that were in progress at March 31, 2017 . Included within the operating results for the three months ended June 30, 2017 were positive changes in estimates of $24.6 million primarily related to favorable mitigation of project risks and the release of related cost contingencies on two natural gas pipeline projects nearing completion in the quarter. Quanta’s operating results for the six months ended June 30, 2017 were impacted by less than 5% as a result of aggregate changes in contract estimates related to projects that were in progress at December 31, 2016 . Quanta’s operating results for the three months ended June 30, 2016 were negatively impacted by 9.2% as a result of aggregate changes in contract estimates related to projects that were in progress at March 31, 2016. Quanta’s operating results for the six months ended June 30, 2016 were negatively impacted by 6.7% as a result of aggregate changes in contract estimates related to projects that were in progress at December 31, 2015 . Operating results for the three and six months ended June 30, 2016 included losses on a power plant construction project in Alaska due to performance issues that resulted in an increase of the estimated total costs necessary to complete the project. During the three and six months ended June 30, 2016 , Quanta recognized project losses of $30.5 million and $51.8 million related to this project. This project was substantially completed during the fourth quarter of 2016. The losses on this project were partially offset by the aggregate positive impact of numerous individually immaterial changes in profitability generally due to better than expected performance on projects that were in progress at December 31, 2015 . The current asset “Costs and estimated earnings in excess of billings on uncompleted contracts” represents revenues recognized in excess of amounts billed for fixed price contracts. The current liability “Billings in excess of costs and estimated earnings on uncompleted contracts” represents billings in excess of revenues recognized for fixed price contracts. Quanta may incur costs subject to change orders, whether approved or unapproved by the customer, and/or claims related to certain contracts. Quanta determines the probability that such costs will be recovered based upon evidence such as past practices with the customer, specific discussions or preliminary negotiations with the customer or verbal approvals. Quanta treats items as costs of contract performance in the period incurred if it is not probable that the costs will be recovered or will recognize revenue if it is probable that the contract price will be adjusted and can be reliably estimated. As of June 30, 2017 and December 31, 2016 , Quanta recognized revenues of $118.9 million and $137.8 million related to change orders and/or claims that were in the process of being negotiated in the normal course of business. These aggregate contract price adjustments represent management’s best estimate of additional contract revenues which have been earned and which management believes are probable of collection. The amounts ultimately realized by Quanta upon final acceptance by its customers could be higher or lower than such estimated amounts; however, such amounts cannot currently be estimated.
Income Taxes	Income Taxes Quanta follows the liability method of accounting for income taxes. Under this method, deferred tax assets and liabilities are recorded for future tax consequences of temporary differences between the financial reporting and tax bases of assets and liabilities and are measured using the enacted tax rates and laws that are expected to be in effect when the underlying assets or liabilities are recovered or settled. Quanta regularly evaluates valuation allowances established for deferred tax assets for which future realization is uncertain. The estimation of required valuation allowances includes estimates of future taxable income. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which those temporary differences become deductible. Quanta considers projected future taxable income and tax planning strategies in making this assessment. If actual future taxable income differs from these estimates, Quanta may not realize deferred tax assets to the extent estimated. Quanta records reserves for income taxes related to certain tax positions in those instances where Quanta considers it more likely than not that additional taxes may be due in excess of amounts reflected on income tax returns filed. When recording reserves for expected tax consequences of uncertain positions, Quanta assumes that taxing authorities have full knowledge of the position and all relevant facts. Quanta continually reviews exposure to additional tax obligations, and as further information is known or events occur, changes in tax reserves may be recorded. To the extent interest and penalties may be assessed by taxing authorities on any underpayment of income tax, such amounts have been accrued and included in the provision for income taxes. As of June 30, 2017 , the total amount of unrecognized tax benefits relating to uncertain tax positions was $36.3 million , an increase from December 31, 2016 of $1.1 million . This increase in unrecognized tax benefits resulted primarily from tax positions to be taken for 2017 . Although the Internal Revenue Service completed its examination related to tax years 2010, 2011 and 2012 during the year ended December 31, 2016 , certain subsidiaries remain under examination by various U.S. state, Canadian and other foreign tax authorities for multiple periods. Quanta believes it is reasonably possible that within the next 12 months unrecognized tax benefits may decrease by up to $13.4 million as a result of settlement of these examinations or as a result of the expiration of certain statute of limitations periods. U.S. federal and state and foreign income tax laws and regulations are voluminous and are often ambiguous. As such, Quanta is required to make many subjective assumptions and judgments regarding its tax positions that could materially affect amounts recognized in its future consolidated balance sheets, consolidated statements of operations and consolidated statements of comprehensive income.
Earnings Per Share	Earnings Per Share Basic and diluted earnings per share attributable to common stock are computed using the weighted average number of common shares outstanding during the periods. Exchangeable shares that were issued pursuant to certain of Quanta’s historical acquisitions (as further discussed in Note 8), which are exchangeable on a one-for-one basis with shares of Quanta common stock, have been included in the calculation of weighted average shares outstanding for basic and diluted earnings per share attributable to common stock for the portion of the periods that they were outstanding. Additionally, unvested stock-based awards that contain non-forfeitable rights to dividends or dividend equivalents (participating) have been included in the calculation of basic and diluted earnings per share attributable to common stock for the portion of the periods that they were outstanding. Diluted earnings per share attributable to common stock is computed using the weighted average number of common shares outstanding during the period adjusted for all potentially dilutive common stock equivalents, except in cases where the effect of the common stock equivalents would be antidilutive.
Self-Insurance	Self-Insurance Quanta is insured for employer’s liability, workers’ compensation, auto liability and general liability claims. Under these programs, the deductible for employer’s liability is $1.0 million per occurrence, the deductible for workers’ compensation is $5.0 million per occurrence, and the deductibles for auto liability and general liability are $10.0 million per occurrence. Quanta is generally self-insured for all claims that do not exceed the amount of the applicable deductible. Quanta also has employee health care benefit plans for most employees not subject to collective bargaining agreements, of which the primary plan is subject to a deductible of $0.4 million per claimant per year. Losses under all of these insurance programs are accrued based upon Quanta’s estimate of the ultimate liability for claims reported and an estimate of claims incurred but not reported, with assistance from third-party actuaries. These insurance liabilities are difficult to assess and estimate due to unknown factors, including the severity of an injury, the extent of damage, the determination of Quanta’s liability in proportion to other parties and the number of incidents not reported. The accruals are based upon known facts and historical trends, and management believes such accruals are adequate.
Collective Bargaining Agreements	Collective Bargaining Agreements Some of Quanta’s operating units are parties to various collective bargaining agreements with unions that represent certain of their employees. The collective bargaining agreements expire at various times and have typically been renegotiated and renewed on terms similar to those in the expiring agreements. The agreements require the operating units to pay specified wages, provide certain benefits to their union employees and contribute certain amounts to multiemployer pension plans and employee benefit trusts. Quanta’s multiemployer pension plan contribution rates generally are specified in the collective bargaining agreements (usually on an annual basis), and contributions are made to the plans on a “pay-as-you-go” basis based on its union employee payrolls. The location and number of union employees that Quanta employs at any given time and the plans in which they may participate vary depending on the projects Quanta has ongoing at that time and the need for union resources in connection with those projects. Therefore, Quanta is unable to accurately predict the union employee payroll and the amount of the resulting multiemployer pension plan contribution obligation for future periods.
Stock-Based Compensation	Stock-Based Compensation Quanta recognizes compensation expense for restricted stock, restricted stock units (RSUs) and performance units to be settled in common stock based on the fair value of the awards at the date of grant, net of estimated forfeitures. The fair value of restricted stock awards, RSUs and performance units to be settled in common stock is determined based on the number of shares or units granted and the closing price of Quanta’s common stock on the date of grant or the fair value as determined using a Monte Carlo simulation for performance units with market-based metrics. An estimate of future forfeitures is utilized to determine the period expense. Quanta uses historical data to estimate the forfeiture rate; however, these estimates are subject to change and may impact the value that will ultimately be recognized as compensation expense. The resulting compensation expense from performance unit and time-based RSU awards is recognized on a straight-line basis over the requisite service period, which is generally the vesting period, while compensation expense from performance-based RSU awards is recognized using the graded vesting method over the requisite service period. However, compensation expense related to performance units can vary from period to period based on changes in the total number of performance units that Quanta anticipates will vest. Payments made by Quanta to satisfy employees’ tax withholding obligations associated with awards settled in common stock are classified as financing cash flows. Compensation expense associated with liability based awards, such as RSUs that are expected to or may settle in cash, is recognized based on a remeasurement of the fair value of the award at the end of each reporting period. Upon settlement, the holders receive for each RSU an amount in cash equal to the fair market value on the settlement date of one share of Quanta common stock, as specified in the applicable award agreement. For additional information on Quanta’s restricted stock, RSU and performance unit awards, see Note 9.
Functional Currency and Translation of Financial Statements	Functional Currency and Translation of Financial Statements The U.S. dollar is the functional currency for the majority of Quanta’s operations, which are primarily located within the United States. The functional currency for Quanta’s foreign operations, which are primarily located in Canada and Australia, is typically the currency of the country in which the foreign operating unit is located. Generally, the currency in which the operating unit transacts the majority of its activities, including billings, financing, payroll and other expenditures, would be considered the functional currency. The treatment of foreign currency translation gains or losses is dependent upon management’s determination of the functional currency of each operating unit. In preparing the consolidated financial statements, Quanta translates the financial statements of its foreign operating units from their functional currency into U.S. dollars. Statements of operations, comprehensive income and cash flows are translated at average monthly rates, while balance sheets are translated at month-end exchange rates. The translation of the balance sheet results in translation gains or losses, which are included as a separate component of equity under “Accumulated other comprehensive income (loss)”. Gains and losses arising from transactions which are not denominated in the operating units’ functional currencies are included within “Other income (expense)” in the condensed consolidated statements of operations.
Comprehensive Income	Comprehensive Income Components of comprehensive income include all changes in equity during a period except those resulting from changes in Quanta’s capital related accounts. Quanta records other comprehensive income (loss) for foreign currency translation adjustments related to its foreign operations and for other revenues, expenses, gains and losses that are included in comprehensive income but excluded from net income.
Litigation Costs and Reserves	Litigation Costs and Reserves Quanta records reserves when the likelihood of incurring a loss is probable and the amount of loss can be reasonably estimated. Costs incurred for litigation are expensed as incurred. Further details are presented in Note 10.
Fair Value Measurements	Fair Value Measurements The carrying values of cash equivalents, accounts receivable and accounts payable and accrued expenses approximate fair value due to the short-term nature of these instruments. The carrying value of variable rate debt also approximates fair value. For disclosure purposes, qualifying assets and liabilities are categorized into three broad levels based on the priority of the inputs used to determine their fair values. The fair value hierarchy gives the highest priority to quoted prices (unadjusted) in active markets for identical assets or liabilities (Level 1) and the lowest priority to unobservable inputs (Level 3). All of Quanta’s cash equivalents were categorized as Level 1 assets at June 30, 2017 and December 31, 2016 , as all values were based on unadjusted quoted prices for identical assets in an active market that Quanta has the ability to access. In connection with Quanta’s acquisitions, identifiable intangible assets acquired typically include goodwill, backlog, customer relationships, trade names, covenants not-to-compete, patented rights and developed technology. Quanta utilizes the fair value premise as the primary basis for its valuation procedures, which is a market-based approach to determine the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. Quanta periodically engages the services of an independent valuation firm when a new business is acquired to assist management with this valuation process, including assistance with the selection of appropriate valuation methodologies and the development of market-based valuation assumptions. Based on these considerations, management utilizes various valuation methods, including an income approach, a market approach and a cost approach, to determine the fair value of intangible assets acquired based on the appropriateness of each method in relation to the type of asset being valued. The assumptions used in these valuation methods are analyzed and compared, where possible, to available market data, such as industry-based weighted average costs of capital and discount rates, trade name royalty rates, public company valuation multiples and recent market acquisition multiples. In accordance with its annual impairment test during the quarter ended December 31, 2016 , the carrying amounts of such assets, including goodwill, were compared to their fair values. The level of inputs used for these fair value measurements is the lowest level (Level 3). Quanta uses the assistance of third party specialists to develop valuation assumptions. Quanta believes that these valuation methods appropriately represent the methods that would be used by other market participants in determining fair value. Quanta also uses fair value measurements in connection with the valuation of its investments in private company equity interests and financing instruments. These valuations require significant management judgment due to the absence of quoted market prices, the inherent lack of liquidity and the long-term nature of such assets. Typically, the initial costs of these investments are considered to represent fair market value, as such amounts are negotiated between willing market participants. On a quarterly basis, Quanta performs an evaluation of its investments to determine if an other-than-temporary decline in the value of each investment has occurred and whether the recorded amount of each investment will be realizable. If an other-than-temporary decline in the value of an investment occurs, a fair value analysis would be performed to determine the degree to which the investment was impaired and a corresponding charge to earnings would be recorded during the period. These types of fair market value assessments are similar to other nonrecurring fair value measures used by Quanta, which include the use of significant judgment and available relevant market data. Such market data may include observations of the valuation of comparable companies, risk adjusted discount rates and an evaluation of the expected performance of the underlying portfolio asset, including historical and projected levels of profitability or cash flows. In addition, a variety of additional factors may be reviewed by management, including, but not limited to, contemporaneous financing and sales transactions with third parties, changes in market outlook and the third-party financing environment.
Adoption of New Accounting Pronouncements	Adoption of New Accounting Pronouncements In July 2015 , the FASB issued an update that requires inventory to be measured at the lower of either cost or net realizable value. When evidence exists that the net realizable value of inventory is lower than its cost, the difference will be recognized as a loss in earnings in the period in which it occurs. Quanta adopted this guidance effective January 1, 2017 , and the adoption of the update did not have a significant impact on Quanta’s consolidated financial statements or related disclosures. In March 2016 , the FASB issued an update that amends the accounting for share-based payments in several key areas, including the treatment and cash flow presentation of tax effects related to the settlement of share-based payments and the accounting for forfeitures of share-based awards. The new guidance requires companies with share-based payments to record all tax effects related thereto at settlement (or expiration) through income tax expense on the statement of operations rather than through additional paid-in capital (APIC) within equity. This update also requires excess tax benefits to be classified as an operating activity on the statement of cash flows rather than reclassified as a financing activity and requires cash paid by an employer when withholding shares for the employee portion of taxes to be presented as a financing activity. The update also allows companies to either account for forfeitures of share-based payments as they occur or to estimate forfeitures. This guidance is required to be applied prospectively except for the classification of cash related to tax withholding, which requires retrospective application. Quanta adopted this guidance effective January 1, 2017 and will continue to estimate forfeitures of share-based payments. Quanta anticipates increased volatility of income tax expense after adoption of this guidance, and during the three and six months ended June 30, 2017 recorded income tax benefits of $0.1 million and $5.0 million related to the settlement of share-based awards. APIC was not adjusted for amounts recorded prior to 2017, and therefore Quanta’s retained earnings were not affected by the adoption of this guidance. Additionally, $1.2 million and $7.2 million were reclassified from operating activities to financing activities on the statements of cash flows for the three and six months ended June 30, 2016 associated with cash paid by Quanta to satisfy tax withholding obligations for share-settled awards. Further, the presentation of excess tax benefits on the statements of cash flows is now shown as cash flows from operating activities rather than in financing activities. The excess tax benefits reclassified to operating activities for both the three and six months ended June 30, 2016 were $0.1 million . In October 2016 , the FASB issued an update that amends the consolidation guidance related to how a reporting entity that is the single decision maker of a VIE should treat indirect interests in the VIE held through related parties that are under common control with the reporting entity when determining whether it is the primary beneficiary of a VIE. A reporting entity has an indirect interest in a VIE if it has a direct interest in a related party that, in turn, has a direct interest in the VIE. Quanta adopted this guidance on January 1, 2017 , and the adoption of the update did not have a significant impact on its consolidated financial statements or related disclosures. Accounting Standards Not Yet Adopted In May 2014 , the FASB issued an update that supersedes most current revenue recognition guidance, as well as some cost recognition guidance. The update requires that the recognition of revenue related to the transfer of goods or services to customers reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. This update also requires new qualitative and quantitative disclosures about the nature, amount, timing and uncertainty of revenues and cash flows arising from customer contracts, including significant judgments and changes in judgments, information about contract balances and performance obligations, and assets recognized from costs incurred to obtain or fulfill a contract. In July 2015, the FASB affirmed its proposal to defer the effective date until fiscal years beginning on or after December 15, 2017 . The guidance can be applied on a full retrospective or modified retrospective basis whereby the entity records a cumulative effect of initially applying this update at the date of initial application. Quanta is currently evaluating the potential impact of this update on its consolidated financial statements and anticipates adopting the update using the modified retrospective transition method, which may result in a cumulative-effect adjustment recorded in retained earnings. While Quanta is still evaluating the requirements of this update, it currently does not expect the update to materially affect its results of operations, financial position or cash flows. This preliminary conclusion is based on Quanta’s belief that it will generally continue to recognize revenues from long-term service contracts over time as services are performed and the underlying obligation to the customer is fulfilled. Quanta has identified and is in the process of implementing changes to its processes and internal controls to meet the reporting and disclosure requirements of this update and will adopt this update effective January 1, 2018 . In January 2016 , the FASB issued an update that addresses certain aspects of recognition, measurement, presentation, and disclosure of financial instruments to provide users of financial statements with more decision-useful information. The new standard is effective for interim and annual periods beginning after December 15, 2017 . Quanta is evaluating the impact of the new standard on its consolidated financial statements and will adopt the new standard by January 1, 2018 . In February 2016 , the FASB issued an update that requires companies to recognize on the balance sheet the contractual right to use assets and liabilities corresponding to the rights and obligations created by lease contracts. The new standard is effective for interim and annual periods beginning after December 15, 2018 . While Quanta continues to evaluate the effect of the standard on its consolidated financial statements, it is anticipated that the adoption of the standard will materially impact its statement of financial position. In June 2016 , the FASB issued an update that will change the way companies measure credit losses for most financial assets and certain other instruments that are not measured at fair value through net income. The update will require companies to use an “expected loss” model for instruments measured at amortized cost and to record allowances for available-for-sale debt securities rather than reduce the carrying amounts. The update will also require disclosure of information regarding how a company developed its allowance, including changes in the factors that influenced management’s estimate of expected credit losses and the reasons for those changes. Companies will apply this standard’s provisions as a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is effective. The new standard is effective for interim and annual reporting periods beginning after December 15, 2019 . Quanta is currently evaluating the potential impact of this authoritative guidance on its consolidated financial statements and will adopt this guidance by January 1, 2020 . In August 2016 , the FASB issued an update intended to standardize the classification of certain transactions on the statement of cash flows . These transactions include contingent consideration payments made after a business combination, proceeds from the settlement of corporate-owned life insurance policies and distributions received from equity method investments. The new standard is effective for interim and annual reporting periods beginning after December 15, 2017 and requires application using a retrospective transition method. Quanta is currently evaluating the potential impact of this authoritative guidance on its consolidated financial statements and will adopt this guidance by January 1, 2018 . In October 2016 , the FASB issued an update that will require a reporting entity to recognize the tax expense from the sale of an asset in the seller’s tax jurisdiction when the transfer occurs, even though the pre-tax effects of that transaction are eliminated in consolidation. Any deferred tax asset that arises in the buyer’s jurisdiction would also be recognized at the time of the transfer. The new guidance will not apply to intra-entity transfers of inventory. The income tax consequences from the sale of inventory from one member of a consolidated entity to another will continue to be deferred until the inventory is sold to a third party. The new standard is effective for interim and annual reporting periods beginning after December 15, 2017 . The modified retrospective method will be required for transition to the new guidance, with a cumulative-effect adjustment recorded in retained earnings as of the beginning of the period of adoption. Quanta is currently evaluating the potential impact of this authoritative guidance on its consolidated financial statements and will adopt this guidance by January 1, 2018 . In November 2016 , the FASB issued an update intended to standardize the classification of restricted cash and cash equivalents transactions on the statement of cash flows . The new standard is effective for interim and annual reporting periods beginning after December 15, 2017 . The retrospective transition method will be required for this new guidance. Quanta is currently evaluating the potential impact of this authoritative guidance on its consolidated financial statements and will adopt this guidance by January 1, 2018 . In January 2017 , the FASB issued an update intended to clarify whether transactions should be accounted for as acquisitions or disposals of assets or businesses. When substantially all of the fair value of the gross assets acquired or disposed of is concentrated in a single identifiable asset or group of similar identifiable assets, the asset or group is not a business. The update will require, among other things, that to be considered a business, a set of assets and activities must include, at a minimum, an input and a substantive process that together significantly contribute to the ability to create output. Additionally, the update will remove the evaluation of whether a market participant could replace missing elements in order to consider the set of assets and activities a business, will provide more stringent criteria for sets without outputs and will narrow the definition of output. The new standard is effective for interim and annual reporting periods beginning after December 15, 2017 and the prospective transition method will be required for this new guidance. Quanta is currently evaluating the potential impact of this authoritative guidance on its consolidated financial statements and will adopt this guidance by January 1, 2018 . Also in January 2017 , the FASB issued an update intended to simplify the subsequent measurement of goodwill by eliminating the second step in the current two-step goodwill impairment test. The update will require an entity to perform its annual, or interim, goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount. An entity will recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value, if applicable. Additionally, the update will eliminate the requirement that a reporting unit with a zero or negative carrying amount perform a qualitative assessment and the second step of the two-step goodwill impairment test and will instead require disclosure of the amount of goodwill allocated to each reporting unit with a zero or negative carrying amount of net assets. This update is effective for interim and annual reporting periods beginning after December 15, 2019 . The prospective transition method will be required for this new guidance. Quanta is currently evaluating the potential impact of this authoritative guidance on its consolidated financial statements and will adopt this guidance by January 1, 2020 . In May 2017 , the FASB issued an update providing guidance about which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting. A modification should be accounted for unless the following characteristics of the award are unchanged: the fair value, the vesting conditions and the classification as an equity instrument or a liability instrument. The update is effective for interim and annual periods beginning after December 15, 2017 and is required to be applied prospectively. Quanta is evaluating the impact of the new accounting standard on its consolidated financial statements and will adopt the new standard by January 1, 2018 .
Repurchase of Common Stock	Stock repurchases During the second quarter of 2017, Quanta’s board of directors approved a stock repurchase program that authorizes Quanta to purchase, from time to time through June 30, 2020, up to $300.0 million of its outstanding common stock (the 2017 Repurchase Program). Repurchases under the 2017 Repurchase Program can be made in open market and privately negotiated transactions. As of June 30, 2017 , Quanta had not repurchased any shares of its common stock under the 2017 Repurchase Program. During the third quarter of 2015, Quanta’s board of directors approved a stock repurchase program that authorized Quanta to purchase, from time to time through February 28, 2017, up to $1.25 billion of its outstanding common stock (the 2015 Repurchase Program). Repurchases under the 2015 Repurchase Program were made in open market and privately negotiated transactions, including pursuant to an accelerated share repurchase arrangement and an issuer repurchase plan. During 2015, Quanta repurchased 19.2 million shares of its common stock at a cost of $449.9 million in the open market under the 2015 Repurchase Program. During the third quarter of 2015, Quanta also entered into an accelerated share repurchase arrangement (the ASR) to repurchase $750.0 million of its common stock under the 2015 Repurchase Program. Under the terms of the ASR, Quanta paid $750.0 million to JPMorgan Chase Bank, National Association, London Branch (JPMorgan) and initially received 25.7 million shares of its common stock. The fair market value of these 25.7 million shares at the time of delivery was $600.0 million , and the repurchased shares and the related cost to acquire them were accounted for as an adjustment to the balance of treasury stock during the third quarter of 2015, reducing the weighted-average number of basic and diluted common shares used to calculate Quanta’s earnings per share. The $150.0 million remaining under the ASR was recorded as an adjustment to APIC during the third quarter of 2015 and was reclassified from APIC to treasury stock upon final settlement of the ASR on April 12, 2016 . At final settlement and based on the final volume-weighted average share price during the term of the ASR, minus a discount and subject to other adjustments pursuant to the terms and conditions of the ASR, Quanta received 9.4 million additional shares of its common stock from JPMorgan. The 2015 Repurchase Program ended on February 28, 2017, and Quanta repurchased a total of 54.3 million shares of its common stock at a cost of $1.20 billion under the 2015 Repurchase Program. Other than the shares received at settlement of the ASR in the second quarter of 2016, no common stock was repurchased in the six months ended June 30, 2017 or 2016 under the 2015 Repurchase Program.
Segment Reporting	Quanta presents its operations under two reportable segments: (1) Electric Power Infrastructure Services and (2) Oil and Gas Infrastructure Services. This structure is generally based on the broad end-user markets for Quanta’s services. See Note 1 for additional information regarding Quanta’s reportable segments. Quanta’s segment results are derived from the types of services provided across its operating units in each of the end user markets described above. Quanta’s entrepreneurial business model allows each of its operating units to serve the same or similar customers and to provide a range of services across end user markets. Quanta’s operating units are organized into one of two internal divisions, namely, the Electric Power Infrastructure Services Division and the Oil and Gas Infrastructure Services Division. These internal divisions are closely aligned with the reportable segments described above based on their operating units’ predominant type of work. Reportable segment information, including revenues and operating income by type of work, is gathered from each operating unit for the purpose of evaluating segment performance in support of Quanta’s market strategies. These classifications of Quanta’s operating unit revenues by type of work for segment reporting purposes can at times require judgment on the part of management. Quanta’s operating units may perform joint infrastructure service projects for customers in multiple industries, deliver multiple types of network services under a single customer contract or provide service across industries. For example, Quanta performs joint trenching projects to install distribution lines for electric power and natural gas customers. In addition, Quanta’s integrated operations and common administrative support at each of its operating units require that certain allocations of shared and indirect costs, such as facility costs and indirect operating expenses, including depreciation and general and administrative costs, be made to determine operating segment profitability. Corporate costs, such as payroll and benefits, employee travel expenses, facility costs, professional fees, acquisition costs and amortization related to intangible assets are not allocated.

Acquisitions (Tables)

Acquisitions (Tables)	6 Months Ended
	Jun. 30, 2017
Business Combinations [Abstract]
Summary of Aggregate Consideration Paid or Payable and Allocation of Amounts to the Net Tangible and Identifiable Intangible Assets	The following table summarizes the aggregate consideration paid or payable as of June 30, 2017 for the 2017 acquisition and 2016 acquisitions and presents the allocation of these amounts to the net tangible and identifiable intangible assets based on their estimated fair values as of the respective acquisition dates, inclusive of any purchase price adjustments. This allocation requires a significant use of estimates and is based on information that was available to management at the time these consolidated financial statements were prepared (in thousands). 2017 2016 Consideration: Value of Quanta common stock issued $ 8,267 $ 1,508 Cash paid or payable 5,554 75,941 Contingent consideration — 18,683 Fair value of total consideration transferred or estimated to be transferred $ 13,821 $ 96,132 Current assets $ 6,365 $ 24,233 Property and equipment 890 44,863 Other assets 12 2,553 Identifiable intangible assets 7,053 11,467 Current liabilities (1,983 ) (12,097 ) Deferred tax liabilities, net — (13,484 ) Other long-term liabilities — (5,326 ) Total identifiable net assets 12,337 52,209 Goodwill 1,484 43,923 $ 13,821 $ 96,132
Estimated Fair Values of Identifiable Intangible Assets and Related Weighted Average Amortization	The following table summarizes the estimated fair values of identifiable intangible assets for the 2017 acquisition as of the acquisition date and the related weighted average amortization periods by type (in thousands, except for weighted average amortization periods, which are in years). Estimated Weighted Average Fair Value at Amortization Period in Years Acquisition Date at Acquisition Date Customer relationships $ 6,625 5.0 Non-compete agreements 428 5.0 Total intangible assets subject to amortization acquired in 2017 acquisition $ 7,053 5.0
Unaudited Supplemental Pro Forma Results of Operations	Future results may vary significantly from the results reflected in the following pro forma financial information because of future events and transactions, as well as other factors (in thousands, except per share amounts): Three Months Ended Six Months Ended June 30, June 30, 2017 2016 2017 2016 Revenues $ 2,203,724 $ 1,806,214 $ 4,386,919 $ 3,541,361 Gross profit $ 303,222 $ 203,354 $ 570,996 $ 410,576 Selling, general and administrative expenses $ 186,512 $ 158,603 $ 372,012 $ 319,799 Amortization of intangible assets $ 6,729 $ 8,683 $ 13,644 $ 16,866 Net income $ 64,472 $ 17,080 $ 113,074 $ 38,298 Net income attributable to common stock $ 63,949 $ 16,913 $ 112,378 $ 37,768 Earnings per share attributable to common stock - basic and diluted $ 0.41 $ 0.11 $ 0.72 $ 0.24

Goodwill and Other Intangible23

Goodwill and Other Intangible Assets (Tables)	6 Months Ended
	Jun. 30, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Summary of Changes in Quanta's Goodwill	A summary of changes in Quanta’s goodwill is as follows (in thousands): Electric Power Infrastructure Services Division Oil and Gas Infrastructure Services Division Total Balance at December 31, 2016: Goodwill $ 1,253,979 $ 388,923 $ 1,642,902 Accumulated impairment — (39,733 ) (39,733 ) 1,253,979 349,190 1,603,169 Goodwill acquired during 2017 1,484 — 1,484 Purchase price allocation adjustments (619 ) (659 ) (1,278 ) Foreign currency translation adjustments 7,892 5,050 12,942 Balance at June 30, 2017: Goodwill 1,262,736 394,186 1,656,922 Accumulated impairment — (40,605 ) (40,605 ) $ 1,262,736 $ 353,581 $ 1,616,317
Other Intangible Assets	Quanta’s intangible assets subject to amortization and the remaining weighted average amortization periods related to such assets were as follows (in thousands except for weighted average amortization periods, which are in years): As of As of As of June 30, 2017 December 31, 2016 June 30, 2017 Intangible Assets Accumulated Amortization Intangible Assets, Net Intangible Assets Accumulated Amortization Intangible Assets, Net Remaining Weighted Average Amortization Period in Years Customer relationships $ 254,989 $ (121,292 ) $ 133,697 $ 244,329 $ (110,640 ) $ 133,689 8.2 Backlog 134,967 (134,295 ) 672 133,592 (132,441 ) 1,151 0.7 Trade names 55,439 (14,708 ) 40,731 54,723 (12,855 ) 41,868 17.3 Non-compete agreements 29,958 (26,470 ) 3,488 29,212 (25,546 ) 3,666 2.9 Patented rights and developed technology 22,508 (16,721 ) 5,787 22,480 (15,831 ) 6,649 3.7 Total intangible assets subject to amortization $ 497,861 $ (313,486 ) $ 184,375 $ 484,336 $ (297,313 ) $ 187,023 9.9
Estimated Future Aggregate Amortization Expense of Intangible Assets	The estimated future aggregate amortization expense of intangible assets subject to amortization as of June 30, 2017 is set forth below (in thousands): For the Fiscal Year Ending December 31, Remainder of 2017 $ 13,618 2018 26,061 2019 24,015 2020 22,705 2021 20,368 Thereafter 77,608 Total $ 184,375

Per Share Information (Tables)

Per Share Information (Tables)	6 Months Ended
	Jun. 30, 2017
Earnings Per Share [Abstract]
Basic and Diluted Earnings Per Share Attributable to Common Stock	The amounts used to compute the basic and diluted earnings per share attributable to common stock for the three and six months ended June 30, 2017 and 2016 are illustrated below (in thousands): Three Months Ended Six Months Ended June 30, June 30, 2017 2016 2017 2016 Amounts attributable to common stock: Net income attributable to common stock $ 63,837 $ 16,562 $ 112,104 $ 37,058 Weighted average shares: Weighted average shares outstanding for basic earnings per share attributable to common stock 155,090 156,128 154,859 159,577 Effect of dilutive unvested non-participating stock-based awards 1,075 2 886 2 Weighted average shares outstanding for diluted earnings per share attributable to common stock 156,165 156,130 155,745 159,579

Debt Obligations (Tables)

Debt Obligations (Tables)	6 Months Ended
	Jun. 30, 2017
Debt Disclosure [Abstract]
Long-term Debt Obligations	Quanta’s long-term debt obligations consisted of the following (in thousands): June 30, 2017 December 31, 2016 Borrowings under credit facility $ 480,690 $ 351,341 Other long-term debt, interest rates ranging from 2.4% to 4.3% 1,831 3,305 Capital leases, interest rates ranging from 2.5% to 3.8% 2,492 3,744 Total long-term debt obligations 485,013 358,390 Less — Current maturities of long-term debt 1,375 4,828 Total long-term debt obligations, net of current maturities $ 483,638 $ 353,562
Current Maturities of Long-Term Debt and Short-Term Debt	Quanta’s current maturities of long-term debt and short-term debt consisted of the following (in thousands): June 30, 2017 December 31, 2016 Short-term debt $ — $ 2,735 Current maturities of long-term debt 1,375 4,828 Current maturities of long-term debt and short-term debt $ 1,375 $ 7,563
Information on Borrowings under Credit Facility and Applicable Interest Rates	Borrowings under Quanta’s credit facility and the applicable interest rates during the three and six months ended June 30, 2017 and 2016 were as follows (dollars in thousands): Three Months Ended Six Months Ended June 30, June 30, 2017 2016 2017 2016 Maximum amount outstanding under the credit facility during the period $ 601,062 $ 465,599 $ 601,062 $ 518,607 Average daily amount outstanding under the credit facility $ 518,779 $ 426,172 $ 464,432 $ 449,101 Weighted-average interest rate 2.49 % 2.17 % 2.54 % 2.08 %

Equity-Based Compensation (Tabl

Equity-Based Compensation (Tables)	6 Months Ended
	Jun. 30, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Grant Date Fair Value for Awards of Performance Units Inputs	The grant date fair value for awards of performance units with market-based metrics, which were granted in the six months ended June 30, 2017 , was based on a fair value as determined by a Monte Carlo simulation using the following key inputs: Valuation date stock price based on the March 22, 2017 closing stock price $36.31 Expected volatility 36.00 % Risk-free interest rate 1.46 % Term in years 2.78

Commitments and Contingencies (

Commitments and Contingencies (Tables)	6 Months Ended
	Jun. 30, 2017
Commitments and Contingencies Disclosure [Abstract]
Outstanding Capital Commitments Associated with EPC Investments in Unconsolidated Affiliates	Also as of June 30, 2017 , Quanta had outstanding additional capital commitments associated with investments in an unconsolidated affiliate related to this project as follows (in thousands): Year Ending December 31 — Capital Commitments Remainder of 2017 (1) $ 34,953 2018 — 2019 24,444 Total capital commitments associated with investments in an unconsolidated affiliate related to an EPC electrical transmission project $ 59,397 (1) A return of capital from unconsolidated affiliates of approximately $56.3 million is anticipated in the fourth quarter of 2017 and is not included in these amounts.
Minimum Lease Payments	The following schedule shows the future minimum lease payments under these leases as of June 30, 2017 (in thousands): Operating Leases Year Ending December 31 — Remainder of 2017 $ 58,794 2018 83,916 2019 56,978 2020 34,264 2021 19,605 Thereafter 24,504 Total minimum lease payments $ 278,061

Segment Information (Tables)

Segment Information (Tables)	6 Months Ended
	Jun. 30, 2017
Segment Reporting [Abstract]
Summarized Financial Information	Summarized financial information for Quanta’s reportable segments is presented in the following table (in thousands): Three Months Ended Six Months Ended June 30, June 30, 2017 2016 2017 2016 Revenues: Electric Power Infrastructure Services $ 1,300,729 $ 1,159,087 $ 2,520,231 $ 2,346,089 Oil and Gas Infrastructure Services 899,645 633,343 1,858,313 1,160,078 Consolidated $ 2,200,374 $ 1,792,430 $ 4,378,544 $ 3,506,167 Operating income (loss) : Electric Power Infrastructure Services $ 113,043 $ 75,934 $ 212,715 $ 163,258 Oil and Gas Infrastructure Services 67,751 11,899 106,568 17,740 Corporate and non-allocated costs (71,003 ) (52,364 ) (134,418 ) (108,235 ) Consolidated $ 109,791 $ 35,469 $ 184,865 $ 72,763 Depreciation: Electric Power Infrastructure Services $ 22,150 $ 22,937 $ 44,236 $ 45,882 Oil and Gas Infrastructure Services 18,134 17,254 35,498 33,055 Corporate and non-allocated costs 4,366 2,568 7,609 4,992 Consolidated $ 44,650 $ 42,759 $ 87,343 $ 83,929

Supplemental Cash Flow Inform29

Supplemental Cash Flow Information (Tables)	6 Months Ended
	Jun. 30, 2017
Supplemental Cash Flow Elements [Abstract]
Schedule of Effect of Changes in Operating Assets and Liabilities, Net Of Non-Cash Transactions, On Cash Flows From Operating Activities of Continuing Operations	The net effect of changes in operating assets and liabilities, net of non-cash transactions, on cash flows from operating activities of continuing operations is as follows (in thousands): Three Months Ended Six Months Ended June 30, June 30, 2017 2016 2017 2016 Accounts and notes receivable $ (31,605 ) $ 105,399 $ (126,443 ) $ 264,394 Costs and estimated earnings in excess of billings on uncompleted contracts (67,270 ) (82,456 ) (147,980 ) (134,923 ) Inventories (3,529 ) (2,256 ) (4,798 ) 2,281 Prepaid expenses and other current assets (29,355 ) (13,513 ) (33,637 ) (11,687 ) Accounts payable and accrued expenses and other non-current liabilities (55,848 ) 33,968 13,641 10,324 Billings in excess of costs and estimated earnings on uncompleted contracts 48,020 (48,465 ) 36,206 (12,527 ) Other, net 12,624 3,875 18,842 (999 ) Net change in operating assets and liabilities, net of non-cash transactions $ (126,963 ) $ (3,448 ) $ (244,169 ) $ 116,863
Schedule of Additional Supplemental Cash Flow Information	Additional supplemental cash flow information is as follows (in thousands): Three Months Ended Six Months Ended June 30, June 30, 2017 2016 2017 2016 Cash (paid) received during the period for — Interest paid related to continuing operations $ (4,044 ) $ (3,066 ) $ (7,506 ) $ (5,507 ) Income taxes paid related to continuing operations $ (93,279 ) $ (27,038 ) $ (101,496 ) $ (33,524 ) Income taxes paid related to discontinued operations $ — $ (437 ) $ — $ (6,080 ) Income tax refunds related to continuing operations $ 463 $ 785 $ 2,669 $ 1,679

Business and Organization (Deta

Business and Organization (Detail)	6 Months Ended	12 Months Ended
	Jun. 30, 2017Segment	Dec. 31, 2016Acquisition
Organization And Description Of Business [Line Items]
Number of reportable segments | Segment	2
Acquisitions 2,016
Organization And Description Of Business [Line Items]
Number of business acquisitions | Acquisition		5

Summary of Significant Accoun31

Summary of Significant Accounting Policies - Cash and Cash Equivalents (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	$ 99,565	$ 106,514	$ 112,183	$ 162,344	$ 155,315	$ 128,771
Cash equivalents	8,400		8,800
Domestic Bank Accounts
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	31,400		19,500
Foreign Bank Accounts
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	68,200		92,700
Investments in Joint Ventures
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	13,400		11,500
Domestic Joint Ventures
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	$ 10,500		$ 10,000

Summary of Significant Accoun32

Summary of Significant Accounting Policies - Current and Long-Term Accounts and Notes Receivable and Allowance for Doubtful Accounts (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Accounting Policies [Abstract]
Allowances for doubtful accounts on current receivable	$ 5,279	$ 2,752
Current retainage balances	239,800	231,000
Non-current retainage balances	31,000	5,200
Unbilled receivables	$ 247,400	$ 206,800

Summary of Significant Accoun33

Summary of Significant Accounting Policies - Goodwill and Other Intangibles (Detail)	6 Months Ended	12 Months Ended
	Jun. 30, 2017USD ($)Divisions	Dec. 31, 2016USD ($)Reporting_Unit
Goodwill And Intangible Assets [Line Items]
Number of internal divisions | Divisions	2
Decrease in fair value of reporting units considered for impairment calculation		10.00%
Number of reporting units with fair values that approximated carrying values | Reporting_Unit		2
Goodwill	$ 1,616,317,000	$ 1,603,169,000
Intangible assets	184,375,000	$ 187,023,000
Non-cash charge for impairment of goodwill	0
Oil and Gas Infrastructure Division, Operating Units that have been Negatively Impacted by Various Factors
Goodwill And Intangible Assets [Line Items]
Goodwill	70,700,000
Intangible assets	$ 11,500,000

Summary of Significant Accoun34

Summary of Significant Accounting Policies - Investments in Affiliates and Other Entities (Detail) - Capital for infrastructure projects $ in Millions	Jun. 30, 2017USD ($)
Summary Of Significant Accounting Policies [Line Items]
Other commitment	$ 60
Infrastructure investors partnership
Summary Of Significant Accounting Policies [Line Items]
Other commitment	$ 750

Summary of Significant Accoun35

Summary of Significant Accounting Policies - Revenue Recognition (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Revenue Recognition [Line Items]
Percent increase (decrease) in operating results due to change in contract estimates	10.20%	(9.20%)		(6.70%)
Change in contract estimates	$ 24.6
Change orders and/or claims	$ 118.9		$ 118.9		$ 137.8
Maximum
Revenue Recognition [Line Items]
Percent aggregate change in contract estimates impact on operating results is less than this percentage			5.00%
Alaska Power Plant Construction Project
Revenue Recognition [Line Items]
Losses on contracts		$ 30.5		$ 51.8

Summary of Significant Accoun36

Summary of Significant Accounting Policies - Income Taxes (Detail)	6 Months Ended
	Jun. 30, 2017USD ($)
Income Taxes [Line Items]
Total amount of unrecognized tax benefits relating to uncertain tax positions	$ 36,300,000
Amount of unrecognized tax benefits change from year end relating to uncertain tax positions	1,100,000
Maximum
Income Taxes [Line Items]
Reasonably possible reduction to the balance of unrecognized tax benefits in succeeding 12 months	$ 13,400,000

Summary of Significant Accoun37

Summary of Significant Accounting Policies - Self-Insurance (Detail)	6 Months Ended
	Jun. 30, 2017USD ($)
Accounting Policies [Abstract]
Employer's liability claims subject to deductible per occurrence	$ 1,000,000
Worker's compensation claims per occurrence	5,000,000
Auto liability insurance claims deductible	10,000,000
General liability insurance claims deductible	10,000,000
Employee health care benefit plans subject to deductible per claimant	$ 400,000

Summary of Significant Accoun38

Summary of Significant Accounting Policies - Stock-Based Compensation (Detail)	6 Months Ended
	Jun. 30, 2017shares
Restricted Stock Units to be Settled in Cash
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Amount in cash received for each RSU is equal to the fair value of this number of Quanta common stock shares (in shares).	1

New Accounting Pronouncements (

New Accounting Pronouncements (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Income tax benefit related to the settlement of share-based awards during period	$ 0.1		$ 5
Accounting Standards Update, Statutory Tax Withholding Component
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net cash provided by (used in) operating activities		$ 1.2		$ 7.2
Net cash provided by (used in) financing activities		(1.2)		(7.2)
Accounting Standards Update, Excess Tax Benefit Component
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net cash provided by (used in) operating activities		0.1		0.1
Net cash provided by (used in) financing activities		$ (0.1)		$ (0.1)

Acquisitions (Detail)

Acquisitions (Detail) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2017USD ($)shares	Jun. 30, 2016USD ($)	Jun. 30, 2017USD ($)	Jun. 30, 2016USD ($)	Jun. 30, 2017USD ($)	Dec. 31, 2016USD ($)Acquisitionshares
Business Acquisition [Line Items]
Net tangible assets acquired					$ 22,900
Goodwill acquired			$ 1,484		19,200
Other intangible assets acquired					10,200
Revenues included in consolidated results of operations	$ 2,200,374	$ 1,792,430	4,378,544	$ 3,506,167
Loss (income) before taxes	(104,605)	$ (31,424)	(175,637)	$ (65,726)
Electric Power Infrastructure Services Division
Business Acquisition [Line Items]
Goodwill acquired			1,484
Oil and Gas Infrastructure Services Division
Business Acquisition [Line Items]
Goodwill acquired			0
Acquisitions 2,017
Business Acquisition [Line Items]
Cash paid or payable	$ 5,600		5,554
Number of shares granted for acquired companies (in shares) | shares	288,666
Value of Quanta common stock issued	$ 8,300		8,267
Contingent consideration, liability	0		0		0
Goodwill acquired			1,484
Fair value of accounts receivable acquired	6,300		6,300		6,300
Goodwill expected to be deductible for income tax	1,500		1,500		$ 1,500
Revenues included in consolidated results of operations	2,200		2,200
Loss (income) before taxes	1,800		1,800
Acquisition costs	$ 2,300		2,300
Acquisitions 2017 | Electric Power Infrastructure Services Division
Business Acquisition [Line Items]
Goodwill acquired			$ 1,500
Acquisitions 2,016
Business Acquisition [Line Items]
Cash paid or payable						$ 75,941
Number of shares granted for acquired companies (in shares) | shares						70,840
Value of Quanta common stock issued						$ 1,508
Number of business acquisitions | Acquisition						5
Contingent consideration, maximum						$ 39,500
Contingent consideration, liability						18,683
Goodwill acquired						43,923
Fair value of accounts receivable acquired						14,400
Goodwill expected to be deductible for income tax						$ 2,000
Acquisitions 2016 | Electric Power Infrastructure Services Segment
Business Acquisition [Line Items]
Number of business acquisitions | Acquisition						4
Acquisitions 2016 | Electric Power Infrastructure Services Division
Business Acquisition [Line Items]
Goodwill acquired						$ 23,600
Acquisitions 2016 | Oil and Gas Infrastructure Services Division
Business Acquisition [Line Items]
Goodwill acquired						$ 20,300

Acquisitions - Business Acquisi

Acquisitions - Business Acquisition Purchase Price Allocation Assets Acquired and Liabilities Assumed (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2017	Jun. 30, 2017	Jun. 30, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Goodwill		$ 1,484	$ 19,200
Acquisitions 2,017
Business Acquisition [Line Items]
Value of Quanta common stock issued	$ 8,300	8,267
Cash paid or payable	5,600	5,554
Contingent consideration	0	0	0
Fair value of total consideration transferred or estimated to be transferred		13,821
Current assets	6,365	6,365	6,365
Property and equipment	890	890	890
Other assets	12	12	12
Identifiable intangible assets	7,053	7,053	7,053
Current liabilities	(1,983)	(1,983)	(1,983)
Deferred tax liabilities, net	0	0	0
Other long-term liabilities	0	0	0
Total identifiable net assets	12,337	12,337	12,337
Goodwill		1,484
Fair value of total consideration transferred or estimated to be transferred	$ 13,821	$ 13,821	$ 13,821
Acquisitions 2,016
Business Acquisition [Line Items]
Value of Quanta common stock issued				$ 1,508
Cash paid or payable				75,941
Contingent consideration				18,683
Fair value of total consideration transferred or estimated to be transferred				96,132
Current assets				24,233
Property and equipment				44,863
Other assets				2,553
Identifiable intangible assets				11,467
Current liabilities				(12,097)
Deferred tax liabilities, net				(13,484)
Other long-term liabilities				(5,326)
Total identifiable net assets				52,209
Goodwill				43,923
Fair value of total consideration transferred or estimated to be transferred				$ 96,132

Acquisitions - Estimated Fair V

Acquisitions - Estimated Fair Values of Identifiable Intangible Assets and Related Weighted Average Amortization (Detail) - Acquisitions 2017 $ in Thousands	6 Months Ended
	Jun. 30, 2017USD ($)
Business Acquisition [Line Items]
Estimated fair value at acquisition date	$ 7,053
Weighted average amortization period at acquisition date	5 years
Customer relationships
Business Acquisition [Line Items]
Estimated fair value at acquisition date	$ 6,625
Weighted average amortization period at acquisition date	5 years
Non-compete agreements
Business Acquisition [Line Items]
Estimated fair value at acquisition date	$ 428
Weighted average amortization period at acquisition date	5 years

Acquisitions - Unaudited Supple

Acquisitions - Unaudited Supplemental Pro Forma Results of Operations (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Business Acquisition [Line Items]
Revenues	$ 2,200,374	$ 1,792,430	$ 4,378,544	$ 3,506,167
Gross profit	302,165	200,217	568,353	403,530
Selling, general and administrative expenses	185,880	156,607	370,432	315,131
Amortization of intangible assets	6,494	8,141	13,056	15,636
Net income	64,360	16,729	112,800	37,588
Net income attributable to common stock	$ 63,837	$ 16,562	$ 112,104	$ 37,058
Earnings per share attributable to common stock - basic and diluted (in usd per share)	$ 0.41	$ 0.11	$ 0.72	$ 0.23
Pro Forma | Acquisitions
Business Acquisition [Line Items]
Revenues	$ 2,203,724	$ 1,806,214	$ 4,386,919	$ 3,541,361
Gross profit	303,222	203,354	570,996	410,576
Selling, general and administrative expenses	186,512	158,603	372,012	319,799
Amortization of intangible assets	6,729	8,683	13,644	16,866
Net income	64,472	17,080	113,074	38,298
Net income attributable to common stock	$ 63,949	$ 16,913	$ 112,378	$ 37,768
Earnings per share attributable to common stock - basic and diluted (in usd per share)	$ 0.41	$ 0.11	$ 0.72	$ 0.24

Goodwill and Other Intangible44

Goodwill and Other Intangible Assets - Summary of Changes in Quanta's Goodwill (Detail) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2017	Jun. 30, 2017
Goodwill [Roll Forward]
Goodwill gross, beginning balance	$ 1,642,902
Accumulated impairment, beginning balance	(39,733)
Goodwill, beginning balance	1,603,169
Goodwill acquired	1,484	$ 19,200
Purchase price allocation adjustments	(1,278)
Foreign currency translation adjustments	12,942
Goodwill gross, ending balance	1,656,922	1,656,922
Accumulated impairment, ending balance	(40,605)	(40,605)
Goodwill, ending balance	1,616,317	1,616,317
Electric Power Infrastructure Services Division
Goodwill [Roll Forward]
Goodwill gross, beginning balance	1,253,979
Accumulated impairment, beginning balance	0
Goodwill, beginning balance	1,253,979
Goodwill acquired	1,484
Purchase price allocation adjustments	(619)
Foreign currency translation adjustments	7,892
Goodwill gross, ending balance	1,262,736	1,262,736
Accumulated impairment, ending balance	0	0
Goodwill, ending balance	1,262,736	1,262,736
Oil and Gas Infrastructure Services Division
Goodwill [Roll Forward]
Goodwill gross, beginning balance	388,923
Accumulated impairment, beginning balance	(39,733)
Goodwill, beginning balance	349,190
Goodwill acquired	0
Purchase price allocation adjustments	(659)
Foreign currency translation adjustments	5,050
Goodwill gross, ending balance	394,186	394,186
Accumulated impairment, ending balance	(40,605)	(40,605)
Goodwill, ending balance	$ 353,581	$ 353,581

Goodwill and Other Intangible45

Goodwill and Other Intangible Assets - Other Intangible Assets (Detail) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Intangible Assets	$ 497,861	$ 484,336
Accumulated Amortization	(313,486)	(297,313)
Intangible Assets, Net	$ 184,375	187,023
Remaining Weighted Average Amortization Period in Years	9 years 10 months 24 days
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Intangible Assets	$ 254,989	244,329
Accumulated Amortization	(121,292)	(110,640)
Intangible Assets, Net	$ 133,697	133,689
Remaining Weighted Average Amortization Period in Years	8 years 2 months 12 days
Backlog
Finite-Lived Intangible Assets [Line Items]
Intangible Assets	$ 134,967	133,592
Accumulated Amortization	(134,295)	(132,441)
Intangible Assets, Net	$ 672	1,151
Remaining Weighted Average Amortization Period in Years	8 months 12 days
Trade names
Finite-Lived Intangible Assets [Line Items]
Intangible Assets	$ 55,439	54,723
Accumulated Amortization	(14,708)	(12,855)
Intangible Assets, Net	$ 40,731	41,868
Remaining Weighted Average Amortization Period in Years	17 years 3 months 18 days
Non-compete agreements
Finite-Lived Intangible Assets [Line Items]
Intangible Assets	$ 29,958	29,212
Accumulated Amortization	(26,470)	(25,546)
Intangible Assets, Net	$ 3,488	3,666
Remaining Weighted Average Amortization Period in Years	2 years 10 months 25 days
Patented rights and developed technology
Finite-Lived Intangible Assets [Line Items]
Intangible Assets	$ 22,508	22,480
Accumulated Amortization	(16,721)	(15,831)
Intangible Assets, Net	$ 5,787	$ 6,649
Remaining Weighted Average Amortization Period in Years	3 years 8 months 12 days

Goodwill and Other Intangible46

Goodwill and Other Intangible Assets (Detail) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017USD ($)	Jun. 30, 2016USD ($)	Jun. 30, 2017USD ($)Divisions	Jun. 30, 2016USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
Number of internal divisions | Divisions			2
Amortization of intangible assets | $	$ 6,494	$ 8,141	$ 13,056	$ 15,636

Goodwill and Other Intangible47

Goodwill and Other Intangible Assets - Estimated Future Aggregate Amortization Expense of Intangible Assets (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Remainder of 2017	$ 13,618
2,018	26,061
2,019	24,015
2,020	22,705
2,021	20,368
Thereafter	77,608
Intangible Assets, Net	$ 184,375	$ 187,023

Per Share Information - Basic a

Per Share Information - Basic and Diluted Earnings Per Share Attributable to Common Stock (Detail) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Amounts attributable to common stock:
Net income attributable to common stock	$ 63,837	$ 16,562	$ 112,104	$ 37,058
Weighted average shares:
Weighted average shares outstanding for basic earnings per share attributable to common stock (in shares)	155,090	156,128	154,859	159,577
Effect of dilutive unvested non-participating stock-based awards (in shares)	1,075	2	886	2
Weighted average shares outstanding for diluted earnings per share attributable to common stock (in shares)	156,165	156,130	155,745	159,579

Debt Obligations - Long-term De

Debt Obligations - Long-term Debt Obligations (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Borrowings under credit facility	$ 480,690	$ 351,341
Other long-term debt, interest rates ranging from 2.4% to 4.3%	1,831	3,305
Capital leases, interest rates ranging from 2.5% to 3.8%	2,492	3,744
Total long-term debt obligations	485,013	358,390
Less — Current maturities of long-term debt	1,375	4,828
Total long-term debt obligations, net of current maturities	$ 483,638	$ 353,562
Other Long Term Debt | Minimum
Debt Instrument [Line Items]
Capital leases and Other long-term debt interest rates	2.40%	2.40%
Other Long Term Debt | Maximum
Debt Instrument [Line Items]
Capital leases and Other long-term debt interest rates	4.30%	4.30%
Capital Leases | Minimum
Debt Instrument [Line Items]
Capital leases and Other long-term debt interest rates	2.50%	2.50%
Capital Leases | Maximum
Debt Instrument [Line Items]
Capital leases and Other long-term debt interest rates	3.80%	3.80%

Debt Obligations - Current Matu

Debt Obligations - Current Maturities of Long-Term Debt and Short-Term Debt (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Debt Disclosure [Abstract]
Short-term debt	$ 0	$ 2,735
Current maturities of long-term debt	1,375	4,828
Current maturities of long-term debt and short-term debt	$ 1,375	$ 7,563

Debt Obligations - Credit Facil

Debt Obligations - Credit Facility Amended and Restated Credit Agreement (Detail) - Current Credit Agreement	Jun. 30, 2017USD ($)
Line of Credit Facility [Line Items]
Senior secured revolving credit facility	$ 1,810,000,000
Option to increase revolving commitments under the credit agreement	400,000,000
Revolving Loans and Letters of Credit in Alternative Currencies
Line of Credit Facility [Line Items]
Senior secured revolving credit facility	600,000,000
U S Dollar | Swing Lines Loan
Line of Credit Facility [Line Items]
Senior secured revolving credit facility	100,000,000
Canadian Dollars | Swing Lines Loan
Line of Credit Facility [Line Items]
Senior secured revolving credit facility	50,000,000
Australian Dollars | Swing Lines Loan
Line of Credit Facility [Line Items]
Senior secured revolving credit facility	$ 30,000,000

Debt Obligations - Credit Fac52

Debt Obligations - Credit Facility Current Borrowings (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Line of Credit Facility [Line Items]
Amount borrowed under the credit facility	$ 480,690	$ 351,341
Credit facility available for revolving loans or issuing new letters of credit	1,000,000
Letters Of Credit and Bank Guarantees
Line of Credit Facility [Line Items]
Letters of credit and bank guarantees under the credit facility	324,700
Letters Of Credit and Bank Guarantees | U S Dollar
Line of Credit Facility [Line Items]
Letters of credit and bank guarantees under the credit facility	225,100
Letters Of Credit and Bank Guarantees | Primarily Canadian and Australian Dollars
Line of Credit Facility [Line Items]
Letters of credit and bank guarantees under the credit facility	99,600
Borrowings Under Credit Facility
Line of Credit Facility [Line Items]
Amount borrowed under the credit facility	480,700
Borrowings Under Credit Facility | U S Dollar
Line of Credit Facility [Line Items]
Amount borrowed under the credit facility	326,400
Borrowings Under Credit Facility | Canadian Dollars
Line of Credit Facility [Line Items]
Amount borrowed under the credit facility	$ 154,300

Debt Obligations - Information

Debt Obligations - Information on Borrowings under Current and Prior Credit Facility and Applicable Interest Rates (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Debt Disclosure [Abstract]
Maximum amount outstanding under the credit facility during the period	$ 601,062	$ 465,599	$ 601,062	$ 518,607
Average daily amount outstanding under the credit facility	$ 518,779	$ 426,172	$ 464,432	$ 449,101
Weighted-average interest rate	2.49%	2.17%	2.54%	2.08%

Debt Obligations - Credit Fac54

Debt Obligations - Credit Facility Terms under the Amended and Restated Credit Agreement (Detail) - Current Credit Agreement	6 Months Ended
	Jun. 30, 2017USD ($)
Line of Credit Facility [Line Items]
Reduction in Quanta's funded indebtedness reduced by cash and cash equivalents in excess of this amount	$ 25,000,000
Percentage of capital stock of direct foreign subsidiaries of wholly owned U.S. subsidiaries to secure credit agreement	65.00%
Amount of availability under the credit agreement and/or cash and cash equivalents on hand that must be present to allow for cash payments of dividends and stock repurchases	$ 100,000,000
Cross default provisions with debt instruments exceeding this amount	$ 100,000,000
Minimum
Line of Credit Facility [Line Items]
Commitment fee	0.20%
Minimum | Standby Letters of Credit
Line of Credit Facility [Line Items]
Debt instrument basis spread on variable rate	1.125%
Minimum | Performance Letters of Credit
Line of Credit Facility [Line Items]
Debt instrument basis spread on variable rate	0.675%
Maximum
Line of Credit Facility [Line Items]
Commitment fee	0.40%
Maximum | Standby Letters of Credit
Line of Credit Facility [Line Items]
Debt instrument basis spread on variable rate	2.125%
Maximum | Performance Letters of Credit
Line of Credit Facility [Line Items]
Debt instrument basis spread on variable rate	1.275%
Excess of Eurocurrency Rate Applicable to Domestic Borrowings Only | Minimum
Line of Credit Facility [Line Items]
Debt instrument basis spread on variable rate	1.125%
Excess of Eurocurrency Rate Applicable to Domestic Borrowings Only | Maximum
Line of Credit Facility [Line Items]
Debt instrument basis spread on variable rate	2.125%
Excess of Base Rate Domestic Borrowings Only | Minimum
Line of Credit Facility [Line Items]
Debt instrument basis spread on variable rate	0.125%
Excess of Base Rate Domestic Borrowings Only | Maximum
Line of Credit Facility [Line Items]
Debt instrument basis spread on variable rate	1.125%
Excess of Euro Currency Rate of Credit Agreement for Foreign Borrowings | Minimum
Line of Credit Facility [Line Items]
Debt instrument basis spread on variable rate	1.125%
Excess of Euro Currency Rate of Credit Agreement for Foreign Borrowings | Maximum
Line of Credit Facility [Line Items]
Debt instrument basis spread on variable rate	2.125%
Excess of Federal Funds Rate
Line of Credit Facility [Line Items]
Debt instrument basis spread on variable rate	0.50%
Excess of Euro Currency Rate
Line of Credit Facility [Line Items]
Debt instrument basis spread on variable rate	1.00%

Equity - Exchangeable Shares an

Equity - Exchangeable Shares and Series F and Series G Preferred Stock (Detail)	3 Months Ended		6 Months Ended
	Jun. 30, 2017shares	Jun. 30, 2016shares	Jun. 30, 2017Acquisitionshares	Jun. 30, 2016shares	Dec. 31, 2016shares
Class of Stock [Line Items]
Number of shares of Common stock received for each exchangeable share (in shares)			1
Minimum number of shares that can be exchanged by exchangeable shareholders unless the number of remaining exchangeable shares registered in the name of the holder is less (in shares)			50,000
Number of business acquisitions having issuances of preferred stock | Acquisition			2
Common stock, shares outstanding (in shares)	148,490,467		148,490,467		144,710,773
Series F Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares issued (in shares)	1		1		1
Preferred stock, shares outstanding (in shares)	1		1		1
Series G Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares issued (in shares)	1		1		1
Preferred stock, shares outstanding (in shares)	1		1		1
Exchangeable Shares For Common Stock
Class of Stock [Line Items]
Exchangeable shares exchanged for common stock (in shares)	0	0	2,500,000	0
Exchangeable Shares
Class of Stock [Line Items]
Common stock, shares outstanding (in shares)	3,986,112		3,986,112		6,515,453
Exchangeable Shares Associated With Series F And Series G Preferred Stock [Member]
Class of Stock [Line Items]
Common stock, shares outstanding (in shares)	3,900,000		3,900,000

Equity - Treasury Stock (Detail

Equity - Treasury Stock (Detail) - USD ($)	Dec. 01, 2016	Jun. 30, 2017	Jun. 30, 2016	Sep. 30, 2015	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2015	Dec. 31, 2016	Feb. 28, 2017
Equity, Class of Treasury Stock [Line Items]
Treasury stock, value		$ 35,490,000			$ 35,490,000			$ 14,288,000
Retirement of treasury stock, shares (in shares)	84,800,000
Retirement of treasury stock, amount								$ 1,950,000,000
2017 Repurchase Program
Equity, Class of Treasury Stock [Line Items]
Treasury stock acquired (in shares)					0
2017 Repurchase Program | Maximum
Equity, Class of Treasury Stock [Line Items]
Aggregate authorized amount of common stock to be repurchased		300,000,000			$ 300,000,000
2015 Repurchase Plan Open Market Purchases And Accelerated Share Repurchase Agreement
Equity, Class of Treasury Stock [Line Items]
Treasury stock acquired (in shares)					0	0			54,300,000
Treasury Stock, Value, Acquired, Cost Method									$ 1,200,000,000
2015 Repurchase Program | Maximum
Equity, Class of Treasury Stock [Line Items]
Aggregate authorized amount of common stock to be repurchased				$ 1,250,000,000
2015 Repurchase Program Open Market Purchases
Equity, Class of Treasury Stock [Line Items]
Treasury stock acquired (in shares)							19,200,000
Treasury Stock, Value, Acquired, Cost Method							$ 449,900,000
Accelerated Share Repurchase Agreement
Equity, Class of Treasury Stock [Line Items]
Treasury stock acquired (in shares)				25,700,000				9,400,000
Treasury Stock, Value, Acquired, Cost Method				$ 600,000,000
Aggregate authorized amount of common stock to be repurchased				750,000,000
Payments for repurchase of common stock				750,000,000
Accelerated stock repurchases settled at a later date				$ 150,000,000
Treasury Stock Associated with Deferred Compensation Plans
Equity, Class of Treasury Stock [Line Items]
Treasury Stock, Value, Acquired, Cost Method		200,000	$ 400,000		$ 3,400,000	$ 7,800,000
Treasury stock, value		$ 17,700,000			$ 17,700,000
Common Stock Withheld for Settlement of Employee Tax Liabilities
Equity, Class of Treasury Stock [Line Items]
Treasury stock acquired (in shares)					500,000	400,000
Treasury Stock, Value, Acquired, Cost Method					$ 17,800,000	$ 7,200,000

Equity - Non-controlling Intere

Equity - Non-controlling Interests (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Equity [Abstract]
Net income attributable to non-controlling interests	$ 523	$ 167	$ 696	$ 530
Carrying value of the investments held by Quanta in variable interest entities	2,600		2,600		$ 3,300
Non-controlling interests	2,608		2,608		$ 3,275
Distributions to non-controlling interests	$ 400	$ 0	$ 1,400	$ 0

Equity-Based Compensation - Sto

Equity-Based Compensation - Stock Incentive Plans (Detail)	Jun. 30, 2017shares
2011 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate number of shares of common stock that may be issued (in shares)	11,750,000

Equity-Based Compensation - Res

Equity-Based Compensation - Restricted Stock and RSUs to be Settled in Common Stock (Detail) - USD ($) $ / shares in Units, $ in Thousands, shares in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-cash stock compensation expense	$ 11,557	$ 9,503	$ 23,423	$ 23,222
Restricted Stock Units to be Settled in Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted, shares (in shares)	0.1	0.1	1.2	1.8
Granted, weighted average grant date fair value, per share (in usd per share)	$ 33.32	$ 23.59	$ 37.76	$ 22.11
Unrecognized compensation cost, related to unvested RSUs to be settled in common stock, total	$ 49,200		$ 49,200
Expected weighted average period to recognize compensation cost on RSUs to be settled in common stock (in years)			1 year 10 months 21 days
Restricted Stock and Restricted Stock Units to be Settled in Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards vested (in shares)	0.1	0.1	1.4	1.3
Fair value of restricted stock, vested	$ 3,800	$ 1,100	$ 54,300	$ 26,400
Non-cash stock compensation expense	$ 10,100	$ 8,500	$ 21,300	$ 21,700
Restricted Stock and Restricted Stock Units to be Settled in Common Stock | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period for RSUs to be settled in stock			2 years
Restricted Stock and Restricted Stock Units to be Settled in Common Stock | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period for RSUs to be settled in stock			3 years

Equity-Based Compensation - Per

Equity-Based Compensation - Performance Units to be Settled in Common Stock (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-cash stock-based compensation	$ 11,557	$ 9,503	$ 23,423	$ 23,222
Performance Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Required performance period			3 years
Performance units granted (in shares)		100,000	300,000	300,000
Granted, weighted average grant date fair value, per share (in usd per share)		$ 24.11	$ 17.63	$ 22.86
Non-cash stock-based compensation	$ 1,400	$ 1,000	$ 2,100	$ 1,500
Performance units vested (in shares)	0	0	100,000	0
Number of common shares issued in connection with performance units (in shares)	0	0	100,000	0
Fair value of restricted stock, vested			$ 4,300
Performance Units | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance units performance percentage			0.00%
Performance Units | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance units performance percentage			200.00%

Equity-Based Compensation - Gra

Equity-Based Compensation - Grant Date Fair Value for Awards of Performance Units Inputs (Detail) - Performance Units - $ / shares	6 Months Ended
	Jun. 30, 2017	Mar. 22, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share price (in usd per share)		$ 36.31
Expected volatility	36.00%
Risk-free interest rate	1.46%
Term in years	2 years 9 months 11 days

Equity-Based Compensation - RSU

Equity-Based Compensation - RSUs to be Settled in Cash (Detail) - Restricted Stock Units to be Settled in Cash - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Amount in cash received for each RSU is equal to the fair value of this number of Quanta common stock shares (in shares).			1
Compensation expense related to RSUs to be settled in cash	$ 1.2	$ 1.4	$ 3.9	$ 2.9
Payments to settle liabilities under compensation plan	3.8	$ 2.4	6.1	$ 3.4
Accrued liabilities under compensation plan	$ 2.9		$ 2.9		$ 5.1
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period for RSUs to be settled in cash			2 years
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period for RSUs to be settled in cash			3 years

Commitments and Contingencies -

Commitments and Contingencies - Investments in Affiliates and Other Entities (Detail) $ in Millions	3 Months Ended	33 Months Ended
	Dec. 31, 2017USD ($)	Jun. 30, 2017USD ($)	May 31, 2022USD ($)	Sep. 30, 2017USD ($)	Dec. 31, 2014kVsubstationkm
Other Commitments, Planned Oil and Gas Infrastructure Projects
Other Commitments [Line Items]
Outstanding capital commitment		$ 18.1
Capital for infrastructure projects
Other Commitments [Line Items]
Outstanding capital commitment		60
Scenario, Forecast | Other Commitments, Planned Oil and Gas Infrastructure Projects
Other Commitments [Line Items]
Outstanding capital commitment			$ 17.7	$ 0.4
EPC Electric Transmission Project
Other Commitments [Line Items]
Length of electrical transmission line to be constructed under contract | km					500
Number of substations | substation					2
Voltage of substations | kV					500
Aggregate contributions to this unconsolidated affiliate		26.7
Proceeds from return of capital		3
Corporate Joint Venture | Scenario, Forecast | Other Commitments, Planned Oil and Gas Infrastructure Projects
Other Commitments [Line Items]
Proceeds from return of capital	$ 56.3
Infrastructure investors partnership | Capital for infrastructure projects
Other Commitments [Line Items]
Outstanding capital commitment		$ 750

Commitments and Contingencies64

Commitments and Contingencies - Outstanding Capital Commitments Associated with Investments in Unconsolidated Affiliates (Detail) - Corporate Joint Venture - Other Commitments, Engineering, Procurement and Construction Electric Transmission Project $ in Thousands	Jun. 30, 2017USD ($)
Other Commitments [Line Items]
Capital commitments, Remainder of 2017	$ 34,953
Capital commitments, 2018	0
Capital commitments, 2019	24,444
Total capital commitments associated with investments in an unconsolidated affiliate related to an EPC electrical transmission project	$ 59,397

Commitments and Contingencies65

Commitments and Contingencies - Minimum Lease Payments (Detail) $ in Thousands	Jun. 30, 2017USD ($)
Commitments and Contingencies Disclosure [Abstract]
Minimum lease payments, Remainder of 2017	$ 58,794
Minimum lease payments, 2018	83,916
Minimum lease payments, 2019	56,978
Minimum lease payments, 2020	34,264
Minimum lease payments, 2021	19,605
Minimum lease payments, Thereafter	24,504
Total minimum lease payments	$ 278,061

Commitments and Contingencies66

Commitments and Contingencies - Leases (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Operating Leases [Line Items]
Rent expense related to operating leases	$ 67.8	$ 58.4	$ 132.8	$ 114.8
Residual Value Guarantee
Operating Leases [Line Items]
Maximum guaranteed residual value	$ 588.4		$ 588.4

Commitments and Contingencies67

Commitments and Contingencies - Committed Expenditures (Detail) - Vehicle Fleet Committed Capital $ in Millions	Jun. 30, 2017USD ($)
Unrecorded Unconditional Purchase Obligation [Line Items]
Estimated committed capital in 2017	$ 19
Estimated committed capital in 2018	$ 1.4

Commitments and Contingencies68

Commitments and Contingencies - Legal Proceedings (Detail) $ in Millions	Jun. 30, 2017USD ($)
Maximum | Lorenzo Benton v Telecom Network Specialists Inc
Loss Contingencies [Line Items]
Reasonable possible loss	$ 16.5

Commitments and Contingencies69

Commitments and Contingencies - Concentrations of Credit Risk (Detail) - Customer Concentration Risk - Customer	3 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2017	Jun. 30, 2017	Dec. 31, 2016
Electric Power Infrastructure Services Segment Customer One | Net Receivable Position | Electric Power Infrastructure Services Segment
Concentration Risk [Line Items]
Number of customers representing ten percent or more of concentration risk	1	1	1
Concentration risk percentage		13.00%	16.00%
Oil and Gas Infrastructure Services Segment Customer One | Net Receivable Position | Oil and Gas Infrastructure Services Segment
Concentration Risk [Line Items]
Number of customers representing ten percent or more of concentration risk	1	1
Concentration risk percentage		10.00%
Oil and Gas Infrastructure Services Segment Customer One | Sales Revenue, Net | Oil and Gas Infrastructure Services Segment
Concentration Risk [Line Items]
Concentration risk percentage	10.00%	10.00%

Commitments and Contingencies70

Commitments and Contingencies - Self-Insurance (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Commitment And Contingencies [Line Items]
Insurance and other non-current liabilities	$ 267,491	$ 259,733
Insurance Claims
Commitment And Contingencies [Line Items]
Gross amount accrued for insurance claims	238,100	218,200
Insurance and other non-current liabilities	167,500	162,000
Related insurance recoveries/receivables	24,400	8,700
Related insurance recoveries/receivables included in prepaid expenses and other current assets	16,900	400
Related insurance recoveries/receivables included in other assets net	$ 7,500	$ 8,300

Commitments and Contingencies71

Commitments and Contingencies - Letters of Credit (Detail) $ in Millions	Jun. 30, 2017USD ($)
Letters Of Credit and Bank Guarantees
Loss Contingencies [Line Items]
Letters of credit and bank guarantees under the credit facility	$ 324.7

Commitments and Contingencies72

Commitments and Contingencies - Performance Bonds and Parent Guarantees (Detail) - Performance Bonds $ in Millions	6 Months Ended
	Jun. 30, 2017USD ($)
Guarantor Obligations [Line Items]
Total amount of outstanding performance bonds	$ 3,500
Estimate
Guarantor Obligations [Line Items]
Estimated cost to complete bonded projects	$ 840

Commitments and Contingencies73

Commitments and Contingencies - Collective Bargaining Agreements (Detail) - Withdrawal from Multiemployer Defined Benefit Plan - Central States Plan - USD ($) $ in Millions	33 Months Ended	49 Months Ended
	Jun. 30, 2017	Jun. 30, 2017	Jan. 31, 2016	Jul. 31, 2014	Oct. 09, 2013	Dec. 31, 2011
Loss Contingencies [Line Items]
Amount of withdrawal liability			$ 32.9	$ 39.6		$ 32.6
Payment of withdrawal liability assessment amount	$ 20.7
Acquired Company
Loss Contingencies [Line Items]
Amount of withdrawal liability			$ 4.8		$ 4.8
Payment of withdrawal liability assessment amount		$ 3.9
Amount of withdrawal liability, amount suggested by Plan which is different than amount recorded by company					$ 6.9
Minimum
Loss Contingencies [Line Items]
Amount of withdrawal liability	40.1	40.1
Maximum
Loss Contingencies [Line Items]
Amount of withdrawal liability	$ 55.4	$ 55.4

Commitments and Contingencies74

Commitments and Contingencies - Indemnities (Detail) - Indemnification Agreement $ in Millions	Jun. 30, 2017USD ($)
Loss Contingencies [Line Items]
Pre-acquisition non-U.S.tax obligations and indemnification asset amount recorded	$ 11.4
Pre-acquisition non-U.S.tax obligations and indemnification liability amount recorded	$ 11.4

Segment Information (Detail)

Segment Information (Detail) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017USD ($)	Jun. 30, 2016USD ($)	Jun. 30, 2017USD ($)SegmentDivisions	Jun. 30, 2016USD ($)	Dec. 31, 2016USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | Segment			2
Number of internal divisions | Divisions			2
Revenues	$ 2,200,374	$ 1,792,430	$ 4,378,544	$ 3,506,167
Property and equipment	1,190,333		1,190,333		$ 1,174,094
Foreign Operations
Segment Reporting Information [Line Items]
Revenues	524,500	$ 335,600	1,180,000	$ 688,000
Property and equipment	$ 331,600		$ 331,600		$ 320,700
Foreign Operations | Canada
Segment Reporting Information [Line Items]
Percentage of foreign revenues	80.00%	78.00%	82.00%	73.00%

Segment Information - Summarize

Segment Information - Summarized Financial Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Segment Reporting Information [Line Items]
Revenues	$ 2,200,374	$ 1,792,430	$ 4,378,544	$ 3,506,167
Operating income (loss)	109,791	35,469	184,865	72,763
Depreciation	44,650	42,759	87,343	83,929
Electric Power Infrastructure Services
Segment Reporting Information [Line Items]
Revenues	1,300,729	1,159,087	2,520,231	2,346,089
Operating income (loss)	113,043	75,934	212,715	163,258
Depreciation	22,150	22,937	44,236	45,882
Oil and Gas Infrastructure Services
Segment Reporting Information [Line Items]
Revenues	899,645	633,343	1,858,313	1,160,078
Operating income (loss)	67,751	11,899	106,568	17,740
Depreciation	18,134	17,254	35,498	33,055
Corporate and non-allocated costs
Segment Reporting Information [Line Items]
Operating income (loss)	(71,003)	(52,364)	(134,418)	(108,235)
Depreciation	$ 4,366	$ 2,568	$ 7,609	$ 4,992

Supplemental Cash Flow Inform77

Supplemental Cash Flow Information - Schedule of Effect of Changes in Operating Assets and Liabilities, Net Of Non-Cash Transactions, On Cash Flows From Operating Activities of Continuing Operations (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Supplemental Cash Flow Elements [Abstract]
Accounts and notes receivable	$ (31,605)	$ 105,399	$ (126,443)	$ 264,394
Costs and estimated earnings in excess of billings on uncompleted contracts	(67,270)	(82,456)	(147,980)	(134,923)
Inventories	(3,529)	(2,256)	(4,798)	2,281
Prepaid expenses and other current assets	(29,355)	(13,513)	(33,637)	(11,687)
Accounts payable and accrued expenses and other non-current liabilities	(55,848)	33,968	13,641	10,324
Billings in excess of costs and estimated earnings on uncompleted contracts	48,020	(48,465)	36,206	(12,527)
Other, net	12,624	3,875	18,842	(999)
Net change in operating assets and liabilities, net of non-cash transactions	$ (126,963)	$ (3,448)	$ (244,169)	$ 116,863

Supplemental Cash Flow Inform78

Supplemental Cash Flow Information - Schedule of Additional Supplemental Cash Flow Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Cash (paid) received during the period for -
Notes receivable exchanged	$ 7,100
Continuing Operations
Cash (paid) received during the period for -
Interest paid related to continuing operations	(4,044)	$ (3,066)	$ (7,506)	$ (5,507)
Income taxes paid related to continuing and discontinued operations	(93,279)	(27,038)	(101,496)	(33,524)
Income tax refunds related to continuing operations	463	785	2,669	1,679
Discontinued Operations
Cash (paid) received during the period for -
Income taxes paid related to continuing and discontinued operations	$ 0	$ (437)	$ 0	$ (6,080)

Subsequent Event (Detail)

Subsequent Event (Detail) - Stronghold, Ltd. and Stronghold Specialty, Ltd. - Subsequent event $ in Millions	Jul. 20, 2017USD ($)shares
Subsequent Event [Line Items]
Cash payments to acquire businesses	$ 360
Number of shares granted for acquired companies (in shares) | shares	2,693,680
Value of Quanta common stock issued	$ 90
Contingent consideration, maximum	$ 100