Acquisitions And Other Investments (Narrative) (Detail) (USD $)	12 Months Ended				12 Months Ended						1 Months Ended		1 Months Ended		1 Months Ended		12 Months Ended	1 Months Ended		1 Months Ended			1 Months Ended	3 Months Ended		1 Months Ended		1 Months Ended	3 Months Ended			12 Months Ended		1 Months Ended				1 Months Ended		1 Months Ended		1 Months Ended		1 Months Ended		1 Months Ended	3 Months Ended		1 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 Panama Subsidiary [Member] Segment, Discontinued Operations [Member]	Dec. 31, 2012 Rock Extraction Business [Member] Panama Subsidiary [Member] Segment, Discontinued Operations [Member]	Dec. 31, 2011 Rock Extraction Business [Member] Panama Subsidiary [Member] Segment, Discontinued Operations [Member]	Dec. 31, 2010 Rock Extraction Business [Member] Panama Subsidiary [Member] Segment, Discontinued Operations [Member]	Dec. 31, 2012 Rock Extraction Business [Member] Beneficial Owner [Member] Segment, Discontinued Operations [Member]	Dec. 31, 2012 Long-term Debt [Member]	Dec. 31, 2011 Long-term Debt [Member]	Dec. 31, 2012 Bottom Line Services [Member]	Dec. 02, 2012 Bottom Line Services [Member]	Dec. 31, 2012 Bottom Line Services [Member] Earn-out Arrangements [Member]	Dec. 02, 2012 Bottom Line Services [Member] Earn-out Arrangements [Member]	Dec. 31, 2012 Dynamic Tower [Member]	Dec. 02, 2012 Dynamic Tower [Member]	Dec. 31, 2012 2012 Acquisitions [Member]	Apr. 30, 2011 Cam Com [Member]	Apr. 02, 2011 Cam Com [Member]	Apr. 30, 2011 Cam Com [Member] Earn-out Arrangements [Member]	Apr. 02, 2011 Cam Com [Member] Earn-out Arrangements [Member]	Apr. 02, 2011 Cam Com [Member] Capital Lease Obligations [Member]	Jun. 30, 2011 Halsted [Member]	Jun. 30, 2012 Halsted [Member]	Jun. 30, 2011 Halsted [Member] Long-term Debt [Member]	Jun. 30, 2011 Optima [Member]	Jun. 02, 2011 Optima [Member]	Jun. 30, 2011 Optima [Member] Earn-out Arrangements [Member]	Jun. 30, 2012 Optima [Member] Earn-out Arrangements [Member]	Jun. 02, 2011 Optima [Member] Earn-out Arrangements [Member]	Jun. 02, 2011 Optima [Member] Long-term Debt [Member]	Dec. 31, 2012 2011 Acquisitions [Member]	Dec. 31, 2011 2011 Acquisitions [Member]	Dec. 31, 2010 Nsoso [Member]	Dec. 31, 2010 Nsoso [Member] Earn-out Arrangements [Member]	Dec. 31, 2010 Nsoso [Member] Common Stock [Member]	Dec. 24, 2010 Nsoso [Member] Common Stock [Member]	Dec. 31, 2012 Go Green [Member]	Dec. 02, 2012 Go Green [Member]	May 31, 2011 EC Source [Member]	May 02, 2011 EC Source [Member]	May 31, 2011 EC Source [Member] Earn-out Arrangements [Member]	May 02, 2011 EC Source [Member] Earn-out Arrangements [Member]	May 31, 2011 EC Source [Member] Common Stock [Member]	May 02, 2011 EC Source [Member] Common Stock [Member]	Apr. 30, 2011 Fabcor [Member]	Jun. 30, 2012 Fabcor [Member]	Apr. 02, 2011 Fabcor [Member]	Apr. 30, 2011 Fabcor [Member] Earn-out Arrangements [Member]	Apr. 02, 2011 Fabcor [Member] Earn-out Arrangements [Member]
Business Acquisition [Line Items]
Effective date of acquisition											Dec. 01, 2012				Dec. 01, 2012			Apr. 01, 2011					Jun. 30, 2011			Jun. 01, 2011												Dec. 01, 2012		May 02, 2011						Apr. 01, 2011
Business combination, percentage of voting interests acquired												100.00%				100.00%			100.00%				100.00%				100.00%												100.00%		67.00%							100.00%
Acquisition payments in cash												$ 67,600,000							$ 4,400,000				$ 4,000,000				$ 5,100,000														$ 300,000							$ 24,200,000
Business combination, assumed debt									20,600,000	29,900,000												300,000			7,900,000						2,200,000
Debt assumed and repaid																							4,400,000			800,000																				7,000,000
Purchase price allocation, adjustment, liabilities																								3,900,000
Earn-out period														5 years							5 years									5 years													5 years							5 years
Business combination, contingent consideration arrangements, basis for amount													The earn-out is equal to 20% of the excess, if any, of BLS's annual EBITDA over $17 million dollars payable annually at MasTec's election in common stock, cash or a combination, thereof.							earn-out payable in cash equal to 20% of the excess, if any, of Cam Com’s annual EBITDA over $2.25 million, plus an additional one time cash payment of up to $1.5 million if Cam Com’s EBITDA exceeds $1.5 million for the first twelve months following the acquisition								earn-out, equal to 20% of the excess, if any, of Optima’s annual EBITDA over $3.0 million, plus an additional one-time cash payment of up to approximately $5.0 million if Optima’s EBITDA exceeds $1.5 million in the first twelve months following the date of acquisition. The potential earn-out is payable, at MasTec’s election, in common stock, cash, or a combination thereof.							Future annual earn-out payments for the five years beginning in 2011 are calculated as 27.5% of domestic annualized earnings before tax in excess of $40 million, payable, at MasTec’s sole option, in either cash, shares of MasTec common stock, or any combination thereof.							The earn-out is equal to 20% of the excess, if any, of EC Source’s annual earnings before interest, taxes, depreciation and amortization (“EBITDA”), as defined in the purchase agreement, over $15 million, payable annually at MasTec’s election in common stock, cash or a combination thereof.							The earn-out is equal to 30% of the excess, if any, of Fabcor's annual EBITDA over 3.6 million Canadian dollars (approximately U.S. $3.6 million as of December 31, 2012), payable annually to the seller in cash in Canadian dollars
Estimated fair value of contingent consideration														11,100,000							3,000,000									3,000,000													25,000,000							16,900,000
Purchase price consideration, adjustment																													1,500,000																		1,400,000
Cash payment, previous acquisition																																		40,000,000
Equity issued in business combination, number of shares issued																																				1,875,000								5,129,642
Equity issued in business combination, fair value																																					27,000,000								94,200,000
Business combination, cost of acquired entity, equity interests issued and issuable, fair value method																																				based on the average market price five days before and after the terms of the amendment were agreed to and announced								The fair value of the shares transferred was based on MasTec’s quoted market price on the closing date, discounted by 10%, 15% and 20% for the estimated effect of the first, second and third year transfer restrictions, respectively.
Purchase accounting adjustment, goodwill																																		67,000,000
Less than wholly owned subsidiary, ownership percentage				60.00%
Equity method investment, ownership percentage					34.00%			20.40%
Related party revenues					2,300,000	3,700,000	1,800,000
Related party receivables, equity method investee					3,700,000	6,700,000
Due from related party, equity method investee, non-current portion						4,300,000
Asset impairment charges, cost method investments	0	0	0
Asset impairment charges, equity method investments	0	0	0
Acquiree revenue since acquisition date																	12,900,000															164,700,000	265,300,000
Acquiree net income since acquisition date																	100,000															11,600,000	10,800,000
Business combination, acquisition costs																	$ 700,000																$ 1,600,000