Earnings Per Share (Methodology) (Narrative) (Details)	9 Months Ended
	Sep. 30, 2015
Earnings Per Share [Abstract]
Computation of earnings per share, methodology	Basic earnings or loss per share is computed by dividing net income or loss available to MasTec’s common shareholders by the weighted average number of common shares outstanding for the period. Diluted earnings per share is computed by dividing net income available to MasTec’s common shareholders by the number of fully diluted shares, which includes the effect of dilutive potential issuances of common shares as determined using income from continuing operations, including the potential issuance of common shares upon the exercise, conversion or vesting of outstanding stock options and unvested restricted shares, as calculated under the treasury stock method, as well as shares associated with the Company’s convertible debt securities, which matured and were converted in 2014. If the Company reports a loss, rather than income, from continuing operations, the computation of diluted loss per share excludes dilutive common stock equivalents as their effect would be anti-dilutive. For the nine month period ended September 30, 2015, the Company reported a net loss from continuing operations, and 648,379 dilutive common shares were excluded from the calculation of diluted net loss per share for the related period. Therefore, diluted and basic earnings per share were the same in this period.