Earnings Per Share (Narrative) (Detail) (USD $)	3 Months Ended	12 Months Ended		3 Months Ended						3 Months Ended								3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Mar. 31, 2013 Restricted Stock [Member]	Mar. 31, 2012 Restricted Stock [Member]	Mar. 31, 2013 Convertible Debt [Member] Original 4.0% Notes [Member]		Mar. 31, 2012 Convertible Debt [Member] Original 4.0% Notes [Member]		Mar. 31, 2013 Convertible Debt [Member] New 4.0% Notes [Member]		Mar. 31, 2012 Convertible Debt [Member] New 4.0% Notes [Member]		Mar. 31, 2013 Convertible Debt [Member] Original 4.25% Notes [Member]		Mar. 31, 2012 Convertible Debt [Member] Original 4.25% Notes [Member]		Mar. 31, 2013 Convertible Debt [Member] New 4.25% Notes [Member]		Mar. 31, 2012 Convertible Debt [Member] New 4.25% Notes [Member]		Mar. 31, 2013 Convertible Debt [Member] Total New Senior Convertible Notes [Member]	Mar. 31, 2012 Convertible Debt [Member] Total New Senior Convertible Notes [Member]	Mar. 31, 2013 Convertible Debt [Member] Total Convertible Debt [Member]
Earnings Per Share [Line Items]
Computation of earnings per share, methodology	Basic earnings per share is computed by dividing earnings 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 earnings 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. Potentially dilutive common shares include outstanding stock options and unvested restricted share awards, as calculated under the treasury stock method, as well as shares associated with the Company’s outstanding convertible debt securities.
Anti-dilutive common stock equivalents, shares				0	10,962
Stock repurchase program, amount authorized			$ 150,000,000
Treasury stock acquired, shares		4,900,000	4,600,000
Treasury stock acquired, value		75,000,000	75,000,000
Convertible debt, outstanding principal amount						$ 9,600,000	[1]	$ 9,700,000	[1]	$ 105,322,000	[2]	$ 105,322,000	[2]	$ 3,000,000	[1]	$ 3,000,000	[1]	$ 97,000,000	[2]	$ 97,000,000	[2]			$ 215,000,000
Debt instrument, interest rate						4.00%				4.00%				4.25%				4.25%
Debt instrument, convertible, number of conversion shares, principal amount										6,683,000		6,683,000						6,268,000		6,268,000		13,000,000	13,000,000
Debt instrument, convertible, conversion price per share										$ 15.76		$ 15.76						$ 15.48		$ 15.48

[1] Dilutive shares associated with the Original Convertible Notes are attributable to the underlying principal amounts.

[2] Dilutive shares associated with the New Convertible Notes are attributable to the premium over the respective conversion prices.