Acquisitions and Other Investments Acquisitions and Other Investments - EC Source (Narrative) (Details) (USD $)	12 Months Ended			1 Months Ended		3 Months Ended			1 Months Ended			1 Months Ended					1 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	May 31, 2011 EC Source [Member]	Apr. 30, 2011 EC Source [Member]	Jun. 30, 2011 EC Source [Member]	Dec. 31, 2012 EC Source [Member]	May 02, 2011 EC Source [Member]	Nov. 30, 2010 E C Source Services Llc Investee [Member]	May 31, 2011 Common Stock [Member] EC Source [Member]	May 02, 2011 Common Stock [Member] EC Source [Member]	May 31, 2011 Earn-out Arrangements [Member] EC Source [Member]	May 02, 2011 Earn-out Arrangements [Member] EC Source [Member]	Dec. 31, 2012 Long-term Debt [Member]	Dec. 31, 2011 Long-term Debt [Member]	May 02, 2011 Long-term Debt [Member] Management [Member] EC Source [Member]	May 31, 2011 Order or Production Backlog [Member] EC Source [Member]	May 31, 2011 Noncompete Agreements [Member] EC Source [Member]
Business Acquisition [Line Items]
Payments to acquire equity method investments	$ 0	$ 0	$ 10,854,000						$ 10,000,000
Equity method investment, ownership percentage									33.00%
Equity method investment, additional information									two-year option
Date of acquisition agreement					Apr. 29, 2011
Effective date of acquisition				May 02, 2011
Business combination, percentage of voting interests acquired								67.00%
Business combination, step acquisition, cumulative percentage ownership after all transactions				100.00%
Equity issued in business combination, number of shares issued										5,129,642
Equity issued in business combination, fair value											94,200,000
Acquisition payments in cash								300,000
Earn-out period													5 years
Estimated fair value of contingent consideration													25,000,000
Business combination, contingent consideration arrangements, basis for amount												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.
Business combination, equity interest issued or issuable, description										The MasTec shares issued on the effective date are subject to transfer restrictions, 25% of which lapsed on May 2, 2012, 25% of which will lapse on May 2, 2013, and 50% of which will lapse on May 2, 2014.
Business combination, assumed debt														20,600,000	29,900,000	8,600,000
Assumed debt, balance outstanding							8,600,000
Business combination, cost of acquired entity, equity interests issued and issuable, fair value method										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.
Business combination, step acquisition, equity interest in acquiree, percentage								33.00%
Business combination, step acquisition, equity interest in acquiree, fair value of equity investment								39,600,000
Gain on remeasurement of equity interest in acquiree	0	29,041,000	0			29,000,000
Business combination, step acquisition, equity interest in acquiree, valuation techniques				The fair value of the equity investment was determined based on the implied consideration transferred as of the date of the business combination, discounted for the Company’s lack of control as a minority shareholder.
Finite-lived intangible asset, useful life																	3 years	7 years
Fair value measurements, significant assumptions												The fair value of the earn-out obligation was estimated using an income approach and incorporates significant inputs not observable in the market. Key assumptions in the estimated valuation include the discount rate and probability-adjusted EBITDA projections.
Business combination, contingent consideration arrangements, range of outcomes, value, low													0
Business combination, contingent consideration arrangements, range of outcomes, value, high													$ 55,000,000