Segments and Related Information (Narrative) (Details)	3 Months Ended
Mar. 31, 2019 segment
Segments and Related Information [Line Items]
Segment reporting information, factors used to identify entity's reportable segments	MasTec manages its operations under five operating segments, which represent MasTec’s five reportable segments: (1) Communications; (2) Oil and Gas; (3) Electrical Transmission; (4) Power Generation and Industrial and (5) Other. This structure is generally focused on broad end-user markets for MasTec’s labor-based construction services.
Number of operating segments	5
Number of reportable segments	5
Segment reporting information, description of products and services	All five reportable segments derive their revenue from the engineering, installation and maintenance of infrastructure, primarily in North America.
Segment reporting, description of all other segments	The Other segment includes equity investees, the services of which vary from those provided by the Company’s primary segments, as well as other small business units that perform construction and other services for a variety of international end-markets.
Communications [Member]
Segments and Related Information [Line Items]
Segment reporting information, description of products and services	The Communications segment performs engineering, construction, maintenance and customer fulfillment activities related to communications infrastructure, primarily for wireless and wireline/fiber communications and install-to-the-home customers, and, to a lesser extent, infrastructure for utilities, among others.
Oil and Gas [Member]
Segments and Related Information [Line Items]
Segment reporting information, description of products and services	MasTec performs engineering, construction and maintenance services for oil and natural gas pipelines and processing facilities for the energy and utilities industries through its Oil and Gas segment.
Electrical Transmission [Member]
Segments and Related Information [Line Items]
Segment reporting information, description of products and services	The Electrical Transmission segment primarily serves the energy and utility industries through the engineering, construction and maintenance of electrical transmission lines and substations.
Power Generation and Industrial [Member]
Segments and Related Information [Line Items]
Segment reporting information, description of products and services	The Power Generation and Industrial segment primarily serves energy, utility and other end-markets through the installation and construction of power facilities, including renewables, related electrical transmission infrastructure, ethanol/biofuel facilities and various types of heavy civil and industrial infrastructure.

Description of the types of products and services from which the reportable segment derives its revenue.

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Description of the factors used to identify reportable segments, including the basis of organization (for example, whether management has chosen to organize the enterprise around differences in products and services, geographic areas, regulatory environments, or a combination of factors and whether operating segments have been aggregated to reportable segments).

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Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

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Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

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Description of the sources of revenue included in the "all other" segments category.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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