Acquisitions (Schedule of Business Acquisition Pro Forma Information, Business Acquisitions) (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014
Business Combinations [Line Items]
Business combinations, pro forma information, description		The unaudited supplemental pro forma financial information presented below has been prepared by adjusting the historical results of MasTec to include the historical results of the acquired businesses described above and was then adjusted: (i) to remove one-time acquisition costs, including certain acquisition integration costs; (ii) to increase amortization expense resulting from the incremental intangible assets acquired; (iii) to increase interest expense as a result of the cash consideration paid; (iv) to remove integration-related employee redundancy costs; and (v) to reduce interest expense from debt repaid upon acquisition of the respective businesses. The unaudited supplemental pro forma financial information does not include adjustments to reflect the impact of other cost savings or synergies that may result from these acquisitions.
Unaudited Supplemental Pro Forma Financial Information and Results of Businesses Acquired
Business combinations, pro forma revenue				$ 1,137.4
Business combinations, pro forma net income from continuing operations				11.4
Business combinations, actual of acquirees, revenue (year-over-year impact)		$ 120.5		119.8
Business combinations, actual of acquirees, net (loss) income from continuing operations (year-over-year impact)	[1]	(9.0)		1.0
General and Administrative Expenses [Member]
Unaudited Supplemental Pro Forma Financial Information and Results of Businesses Acquired
Business combination, acquisition and integration related costs		3.6
Business combination, acquisition-related costs				$ 0.3
Communications [Member]
Unaudited Supplemental Pro Forma Financial Information and Results of Businesses Acquired
Business combinations, acquisition integration costs		8.8
Communications [Member] | General and Administrative Expenses [Member]
Unaudited Supplemental Pro Forma Financial Information and Results of Businesses Acquired
Business combinations, acquisition integration costs		8.8	$ 5.3
WesTower [Member] | Communications [Member] | General and Administrative Expenses [Member]
Unaudited Supplemental Pro Forma Financial Information and Results of Businesses Acquired
Business combinations, acquisition integration costs		5.7
Pacer [Member] | Other [Member] | Contracts Accounted for under Percentage-of-Completion [Member] | Canadian Dollars [Member] | Corporate Joint Venture [Member]
Unaudited Supplemental Pro Forma Financial Information and Results of Businesses Acquired
Project losses (in dollars)		$ 5.5

[1] Acquiree net loss from continuing operations for the three month period ended March 31, 2015 includes pre-tax amounts of (i) approximately $5.7 million of acquisition integration costs incurred in connection with the WesTower acquisition; and (ii) project losses of $5.5 million associated with the Company’s proportionate interest in a non-controlled Canadian joint venture. Other acquisition-related costs, including certain acquisition integration costs totaling $3.6 million and $0.3 million for the three month periods ended March 31, 2015 and 2014, respectively, are not included in the above acquiree results for the respective periods. The above results also do not include interest expense associated with consideration paid for these acquisitions.