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Segments and Related Information (Narrative) (Details) $ in Thousands	3 Months Ended					12 Months Ended
	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2017 USD ($) segment	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Segment 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 \| segment						5
Number of reportable segments \| segment						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 four primary segments, as well as other small business units that perform construction and other services for a variety of international end-markets.
Segment reporting, transactions between reportable segments						Intercompany revenue and costs among the reportable segments are de minimis 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 revenue 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.
Restructuring charges		$ 1,400	$ 4,700	$ 5,100	$ 4,100
Goodwill and intangible asset impairment (in dollars)						$ 0	$ 0	$ 78,625
General and administrative expenses						$ 275,103	261,433	265,910
Corporate [Member]
Segment and Related Information [Line Items]
Goodwill and intangible asset impairment (in dollars)								78,600
Corporate [Member] \| Audit Committee Investigation [Member]
Segment and Related Information [Line Items]
General and administrative expenses								16,500
Communications [Member]
Segment 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.
Business combinations, acquisition integration costs (in dollars)								17,800
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.
Restructuring charges							6,300
Oil and Gas [Member] \| Contracts Accounted for under Percentage-of-Completion [Member]
Segment and Related Information [Line Items]
Project losses (in dollars)							13,500
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.
Restructuring charges							8,900
Court mandated mediation settlement charge								12,200
Electrical Transmission [Member] \| Contracts Accounted for under Percentage-of-Completion [Member]
Segment and Related Information [Line Items]
Project losses (in dollars)							15,100
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/biofuel facilities and various types of heavy civil and industrial infrastructure.
Power Generation and Industrial [Member] \| Contracts Accounted for under Percentage-of-Completion [Member]
Segment and Related Information [Line Items]
Project losses (in dollars)								21,400
Primary Segments [Member]
Segment and Related Information [Line Items]
Number of operating segments \| segment						4
Other [Member] \| Contracts Accounted for under Percentage-of-Completion [Member] \| Pacer [Member] \| Joint Venture [Member] \| Canadian Dollars [Member]
Segment and Related Information [Line Items]
Project losses (in dollars)	$ 7,000		$ 5,100			$ 7,900	$ 5,100	$ 16,300