Commitments and Contingencies (Collective Bargaining Agreements and Multi-Employer Plans) (Narrative) (Details) - USD ($)		12 Months Ended
	Mar. 14, 2013	Dec. 31, 2014	Nov. 30, 2014	Dec. 31, 2013	Nov. 30, 2011
Loss Contingencies [Line Items]
Multi-employer plans, collective bargaining agreements, description		Certain of MasTec’s subsidiaries are party to various collective bargaining agreements with unions representing certain of their employees. These agreements require the subsidiaries party to the agreements to pay specified wages, provide certain benefits to their union employees and contribute certain amounts to multi-employer pension plans and employee benefit trusts. The collective bargaining agreements expire at various times and have typically been renegotiated and renewed on terms similar to the ones contained in the expiring agreements.
Multi-Employer Plans, Pension [Member] | Plans from Which the Company Terminated Participation in 2014 [Member]
Loss Contingencies [Line Items]
Multi-employer plans, withdrawal liability			$ 0
Multi-Employer Plans, Pension [Member] | Central States Southeast and Southwest Areas Pension Fund [Member]
Loss Contingencies [Line Items]
Multi-employer plans, withdrawal liability		$ 4,200,000		$ 5,400,000	$ 6,400,000
Multi-Employer Plans, Pension [Member] | Central States Southeast and Southwest Areas Pension Fund [Member] | Withdrawal from Multi-Employer Defined Benefit Plan [Member]
Loss Contingencies [Line Items]
Loss contingency, evaluation of estimated loss		Additionally, in November 2011, the Company, along with other members of the PLCA, voluntarily withdrew from Central States, a defined benefit multi-employer pension plan that is in critical status. In connection with this withdrawal, a $6.4 million withdrawal liability was established based on an estimate provided by the Central States administrator as of the date of withdrawal. The Company began paying installments towards this withdrawal liability in 2013, of which $4.2 million and $5.4 million were outstanding as of December 31, 2014 and 2013, respectively. The Company withdrew from Central States in order to mitigate its liability in connection with the plan; however, Central States has asserted that the PLCA members did not effectively withdraw in 2011 and are, therefore, responsible for a withdrawal liability that includes 2011 contribution amounts. By letter dated March 14, 2013, Central States demanded $11 million in withdrawal liability from the Company, which included 2011 contribution amounts. The Company is vigorously opposing this demand because it believes that it legally and effectively withdrew from Central States in November 2011. If Central States were to prevail in its assertion that the Company withdrew after that date, then the initial amount of the Company’s withdrawal liability would increase to approximately $11 million.
Loss contingency, damages sought, value	$ 11,000,000
Loss contingency, maximum loss		$ 11,000,000