Acquisitions (2013 Acquisitions - Big Country) (Narrative) (Details) - Big Country [Member] CAD in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2014 USD ($)	Dec. 31, 2014 CAD	May. 01, 2013 USD ($)
Business Combinations [Line Items]
Business combinations, effective date	May 01, 2013
Business combinations, percentage of voting interests acquired	100.00%	100.00%
Business combinations, name of acquired entity	Big Country Energy Services, Inc. and its affiliated operating companies (collectively, “Big Country”)
Business combinations, 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, Canada, 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.
Business combinations, 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 combinations, goodwill, expected tax deductible amount (in dollars)			$ 4.0
Earn-Out Arrangements [Member]
Business Combinations [Line Items]
Business combinations, contingent consideration arrangements, basis for amount	The contingent earn-out obligation equals 25% of the excess, if any, of Big Country’s EBITDA above certain thresholds for a five-year period, as set forth in the purchase agreement, and is payable annually in cash in Canadian dollars.
Business combinations, contingent consideration, percentage of excess EBITDA	25.00%
Business combinations, contingent consideration, earn-out period (in years)	5 years
Business combinations, contingent consideration, 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 (in dollars) | CAD		CAD 10
Business combination, contingent consideration arrangements, range of outcomes, value, high (in dollars) | CAD		CAD 79
Business combination, contingent consideration arrangements, range of outcomes, maximum unlimited	there is no maximum earn-out payment amount
Earn-Out Arrangements [Member] | Canadian Dollars [Member]
Business Combinations [Line Items]
Business combination, contingent consideration arrangements, range of outcomes, value, low (in dollars)	$ 9.0
Business combination, contingent consideration arrangements, range of outcomes, value, high (in dollars)	$ 68.0