Acquisitions - 2013 Acquisitions (Narrative) (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended		9 Months Ended		9 Months Ended	3 Months Ended	9 Months Ended
	Sep. 30, 2013 Big Country [Member]	May 02, 2013 Big Country [Member]	Sep. 30, 2013 Big Country [Member] Earn-out Arrangements [Member]	May 02, 2013 Big Country [Member] Earn-out Arrangements [Member]	Sep. 30, 2013 Other 2013 Acquisitions [Member]	Sep. 30, 2013 2013 Acquisitions [Member]	Sep. 30, 2013 2013 Acquisitions [Member]
Business Acquisition [Line Items]
Effective date of acquisition	May 01, 2013
Business combination, percentage of voting interests acquired		100.00%
Business combination, name of acquired entity	Big Country Energy Services, Inc.
Business combination, description of acquired entity	Big Country is a North American oil and gas pipeline and facility construction services company, headquartered in Calgary, Alberta, Canada.  Big Country also has construction offices in Alberta, British Columbia and Saskatchewan, as well as in Wyoming and North Dakota. Big Country's services include oil, natural gas and natural gas liquids gathering systems and pipeline construction; pipeline modification and replacement services; compressor and pumping station construction; and other related services supporting the oil and gas production, processing and transportation industries.				Effective April 1, 2013, MasTec acquired a former subcontractor to its wireless business, which will provide self-perform communications tower construction, installation, maintenance and other services in support of telecommunications infrastructure construction in the Company's communications segment. In addition, effective August 1, 2013, MasTec acquired an electrical transmission services company, which focuses primarily on substation construction activities within the Company's electrical transmission segment.
Business combination, goodwill recognized, description	Goodwill arising from the acquisition represents the estimated value of Big Country's geographic presence in key high growth Canadian markets, its assembled workforce, its management team's industry-specific project management expertise and synergies expected to be achieved from the combined operations of Big Country and MasTec.
Business combination, goodwill, tax deductible amount		$ 4.0
Business combination, contingent consideration arrangements, basis for amount			The contingent earn-out obligation is equal to 25% of the excess, if any, of Big Country’s annual earnings before interest, taxes, depreciation and amortization ("EBITDA") above certain thresholds for a five-year period, as set forth in the purchase agreement, and is payable annually in cash.
Earn-out period				5 years
Fair value measurements, significant assumptions			The fair value of the earn-out liability 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-weighted EBITDA projections.
Business combination, contingent consideration arrangements, range of outcomes, value, low				1
Business combination, contingent consideration arrangements, range of outcomes, value, high				110
Business combination, contingent consideration arrangements, range of outcomes, maximum unlimited			there is no maximum earn-out payment amount.
Acquisition costs						$ 0.3	$ 1.5