Business and Organization	9 Months Ended
Business and Organization	Sep. 30, 2020
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, delivering comprehensive infrastructure solutions for the electric power, energy and communications industries in the United States, Canada, Australia and select other international markets. Quanta reports its results under two reportable segments: (1) Electric Power Infrastructure Services and (2) Pipeline and Industrial Infrastructure Services. Electric Power Infrastructure Services Segment The Electric Power Infrastructure Services segment provides comprehensive network solutions to customers in the electric power and other industries. 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 techniques; and the installation of “smart grid” technologies on electric power networks. In addition, this segment provides services that support the development of renewable energy generation, including solar, wind, hydro power and backup natural gas generation facilities, as well as related switchyards and transmission infrastructure. Services related to, among other things, micro-grids and battery storage are also performed in this segment. This segment also provides comprehensive communications infrastructure services to wireline and wireless telecommunications companies, cable multi-system operators and other customers within the communications industry (including services in connection with 5G wireless deployment); services in connection with the construction of electric power generation facilities; and the design, installation, maintenance and repair of commercial and industrial wiring. This segment also includes a majority of the financial results of Quanta’s postsecondary educational institution, which specializes in pre-apprenticeship training, apprenticeship training and specialized utility task training for electric workers, as well as training for the gas distribution and communications industries. Pipeline and Industrial Infrastructure Services Segment The Pipeline and Industrial Infrastructure Services segment provides comprehensive infrastructure solutions, including design, installation, upgrade, repair and maintenance services, to customers involved in the development, transportation, distribution, storage and processing of natural gas, oil and other products. Services include the upgrade, repair, maintenance and construction of natural gas systems for gas utility customers, as well as pipeline protection, integrity testing, rehabilitation and replacement, and the fabrication of pipeline support systems and related structures and facilities for the pipeline industry. Quanta also provides catalyst replacement services, high-pressure and critical-path turnaround services, instrumentation and electrical services, piping, fabrication and storage tank services to the midstream and downstream industrial energy markets. This segment also provides engineering and construction services for pipeline systems, storage systems and compressor and pump stations, as well as related trenching, directional boring and mechanized welding services. To a lesser extent, this segment serves the offshore energy market and designs, installs and maintains fueling systems and water and sewer infrastructure. Acquisitions During the nine months ended September 30, 2020, Quanta acquired an industrial services business located in Canada that performs catalyst handling services, including changeover and shutdown maintenance, for customers in the refining and chemical industries; an electric power infrastructure business located in the United States that primarily provides underground conduit services; a professional engineering business located in the United States that provides infrastructure engineering and design services to electric utilities, gas utilities and communications services companies, as well as permitting and utility locating services; a contractor located in the United States that provides electric power distribution, transmission and substation maintenance and construction, directional boring and emergency restoration services; and a business located in the United States that specializes in the deployment of short- and long-haul fiber optic cable and utilities. Beginning on the respective acquisition dates, the results of the acquired businesses have been included in Quanta’s consolidated financial statements, with the results of the industrial services business generally included in the Pipeline and Industrial Infrastructure Services segment and the results of the remaining businesses generally included in the Electric Power Infrastructure Services segment. During the year ended December 31, 2019, Quanta acquired The Hallen Construction Co., Inc. (Hallen), a pipeline and industrial services business located in the United States that specializes in gas distribution and transmission services, and to a lesser extent, underground electric distribution and transmission services. During the year ended December 31, 2019, Quanta also acquired two specialty utility foundation and pole-setting contractors serving the southeast United States; an electric power specialty contracting business located in the United States that provides aerial power line and construction support services; a business located in the United States that provides technical training materials to electric utility workers; an electric power company specializing in project management and, to a lesser extent, water and wastewater projects located in the United States; and an electrical infrastructure services business located in Canada. Beginning on the respective acquisition dates, the results of the acquired businesses have been included in Quanta’s consolidated financial statements, with the results of Hallen generally included in the Pipeline and Industrial Infrastructure Services segment and the results of the other acquired businesses generally included in the Electric Power Infrastructure Services segment.