Earnings Per Share (Methodology) (Narrative) (Details)	3 Months Ended
	Mar. 31, 2015
Earnings Per Share [Line Items]
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 or loss per share is computed by dividing net income or loss 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 earnings 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. For the three month period ended March 31, 2015, the Company reported a net loss from continuing operations. As a result, dilutive common shares have been excluded from the calculation of diluted net loss per share for the related period as their effect would have been anti-dilutive. Therefore, diluted net loss per share is the same as basic net loss per share for the three month period ended March 31, 2015.
Convertible Debt [Member] | 2009 Convertible Notes [Member]
Earnings Per Share [Line Items]
Computation of earnings per share, methodology	Until maturity of the 2009 Convertible Notes in 2014, dilutive shares associated with these notes were attributable to the underlying principal amounts and were reflected in the calculation of weighted average diluted earnings per share for the corresponding periods by application of the “if-converted” method.
Convertible Debt [Member] | 2011 Convertible Notes [Member]
Earnings Per Share [Line Items]
Computation of earnings per share, methodology	The 2011 Convertible Notes had an optional cash settlement feature, which allowed the Company to settle the principal amount in cash. Until their maturity in 2014, dilutive shares associated with the 2011 Convertible Notes were derived from the premium value of the notes in excess of their principal amounts, as calculated using the treasury stock method. These shares were referred to as the “premium shares.”