Segments and Related Information (Narrative) (Details) - Dec. 31, 2014 $ in Millions	USD ($)	segment
Segment and Related Information [Line Items]
Segment reporting information, factors used to identify entity's reportable segments		MasTec manages its continuing 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 primarily includes a proportionately consolidated joint venture and other small business units that perform construction services for a variety of end-markets in Canada, Mexico and elsewhere internationally.
Segment reporting, transactions between reportable segments		Intercompany revenues and costs among the reportable segments are de minimus and accounted for as if the sales were to third parties because these items are based on negotiated fees between the segments involved. All intercompany transactions and balances are eliminated in consolidation. Intercompany revenues and costs between entities within a reportable segment are eliminated to arrive at segment totals. Eliminations between segments are separately presented.
Segment reporting, additional information about entity's reportable segments		Segment results include certain allocations of centralized costs such as general liability, medical and workers’ compensation insurance and certain information technology costs. Income tax expense is managed by Corporate on a consolidated basis and is not allocated to the reportable segments.
Communications [Member]
Segment and Related Information [Line Items]
Segment reporting information, description of products and services		The Communications segment performs engineering, construction and maintenance of communications infrastructure primarily related to wireless and wireline/fiber communications and install-to-the-home customers, and, to a lesser extent, infrastructure for electrical utilities.
Business combinations, acquisition integration costs (in dollars) | $	$ 5.3
Oil and Gas [Member]
Segment and Related Information [Line Items]
Segment reporting information, description of products and services		MasTec performs engineering, construction and maintenance services on oil and natural gas pipelines and processing facilities for the energy and utilities industries through its Oil and Gas segment.
Electrical Transmission [Member]
Segment 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]
Segment 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 conventional and renewable power facilities, related electrical transmission infrastructure, ethanol facilities and various types of industrial infrastructure.