Acquisitions (Schedule of Business Acquisition Pro Forma Information, Business Acquisitions) (Details) - USD ($) $ in Millions		3 Months Ended	12 Months Ended
		Dec. 31, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
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 the repayment of acquired debt. 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 Pro Forma Financial Information and Results of Businesses Acquired
Business combinations, pro forma revenue			$ 5,085.2	$ 5,465.9	$ 4,199.6
Business combinations, pro forma net income from continuing operations			130.3	160.8	131.0
Business combinations, actual of acquirees, revenue (year-over-year impact)			565.4	406.6	170.8
Business combinations, actual of acquirees, net (loss) income from continuing operations (year-over-year impact)	[1]		0.7	20.0	11.8
General and Administrative Expenses [Member]
Unaudited Pro Forma Financial Information and Results of Businesses Acquired
Business combinations, other acquisition-related costs			$ 2.7	$ 1.9	$ 0.7
Communications [Member]
Unaudited Pro Forma Financial Information and Results of Businesses Acquired
Business combinations, acquisition integration costs		$ 5.3
Communications [Member] | General and Administrative Expenses [Member]
Unaudited Pro Forma Financial Information and Results of Businesses Acquired
Business combinations, acquisition integration costs		5.3
Communications [Member] | WesTower [Member] | General and Administrative Expenses [Member]
Unaudited Pro Forma Financial Information and Results of Businesses Acquired
Business combinations, acquisition integration costs		$ 5.0

[1] Acquiree net (loss) income from continuing operations for the year ended December 31, 2014 includes approximately $5.0 million of the $5.3 million total acquisition integration costs incurred in connection with the WesTower acquisition. The above results, however, do not include other acquisition-related costs of $2.7 million, $1.9 million and $0.7 million for the years ended December 31, 2014, 2013 and 2012, respectively, which are included within general and administrative expenses in the Company’s consolidated statements of operations. The above results also do not include interest expense associated with consideration paid for these acquisitions.