Business and Organization	12 Months Ended
Business and Organization	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Business and Organization	BUSINESS AND ORGANIZATION: Quanta Services, Inc., (together with its subsidiaries, Quanta), is a leading provider of specialty contracting services, delivering comprehensive infrastructure solutions for the electric and gas utility, communications, pipeline and energy industries in the United States, Canada, Australia and select other international markets. Quanta reports its results under two reportable segments: (1) Electric Power Infrastructure Solutions and (2) Underground Utility and Infrastructure Solutions. Electric Power Infrastructure Solutions Segment The Electric Power Infrastructure Solutions segment provides comprehensive network solutions to customers in the electric power and other industries. Services performed by the Electric Power Infrastructure Solutions segment generally include the design, new construction, upgrade and repair and maintenance of electric power transmission and distribution infrastructure and substation facilities along with other engineering and technical services. This includes solutions for utilities to implement system upgrades to modernize and harden the electric power grid in order to ensure its safety and enhance reliability. This segment also provides emergency restoration services, including the repair of infrastructure damaged by fire and 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 the engineering and construction services for the switchyards and transmission infrastructure needed to interconnect renewable energy generation, including solar, wind, hydro power and backup natural gas generation facilities. Engineering and construction services related to, among other things, micro-grids and battery storage are also performed in this segment. This segment also provides comprehensive design and construction solutions to wireline and wireless communications companies, cable multi-system operators and other customers within the communications industry (including services in connection with 5G wireless deployment); and the design, installation, maintenance and repair of commercial and industrial wiring. This segment also provides aviation services in support of the above services and includes the 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. Underground Utility and Infrastructure Solutions Segment The Underground Utility and Infrastructure Solutions segment provides comprehensive infrastructure solutions, including design, engineering, new construction, upgrade and repair and maintenance services, to customers involved in the transportation, distribution, storage and processing of natural gas, oil and other products. Services include the upgrade, new construction and repair and maintenance of natural gas systems for gas utility customers, as well as pipeline protection, integrity testing, rehabilitation and replacement. 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 and the fabrication of pipeline support systems and related structures and facilities, as well as trenching, directional boring and mechanized welding services related to the above services and in connection with electric power infrastructure solutions. To a lesser extent, this segment includes construction services for the offshore energy market and designs, installs and maintains fueling systems and water and sewer infrastructure. Acquisitions During the year ended December 31, 2020, Quanta acquired a contractor located in the United States that provides electric power distribution, transmission and substation maintenance and construction, directional boring and emergency restoration 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 business located in the United States that provides aviation services primarily for the utility industry; an electric power infrastructure business located in the United States that primarily provides underground conduit services; a business located in the United States that specializes in the deployment of short- and long-haul fiber optic cable and utilities; 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; and a business located in the United States that provides heavy, civil, industrial and energy related services and specializes in the construction and maintenance of pipelines and metering stations. During the year ended December 31, 2019, Quanta acquired an underground utility and infrastructure solutions 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 solutions business located in Canada. During the year ended December 31, 2018, Quanta acquired an electrical infrastructure solutions business specializing in substation construction and relay services, a postsecondary educational institution that provides training and programs for workers in the industries Quanta serves, and two communications infrastructure solutions businesses, all of which are located in the United States.