Acquisitions and Other Investments Acquisitions and Other Investments - BLS (Narrative) (Details) (Bottom Line Services [Member], USD $) In Millions, unless otherwise specified	1 Months Ended
	Dec. 31, 2012	Dec. 02, 2012
Business Acquisition [Line Items]
Effective date of acquisition	Dec. 01, 2012
Business combination, percentage of voting interests acquired		100.00%
Acquisition payments in cash		$ 67.6
Business combination, goodwill, expected tax deductible amount		1.6
Earn-out Arrangements [Member]
Business Acquisition [Line Items]
Earn-out period		5 years
Estimated fair value of contingent consideration		11.1
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.
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-weighted EBITDA projections.
Business combination, contingent consideration arrangements, range of outcomes, value, low		0
Business combination, contingent consideration arrangements, range of outcomes, value, high		$ 22
Trade Names [Member]
Business Acquisition [Line Items]
Finite-lived intangible asset, useful life	10 years
Noncompete Agreements [Member]
Business Acquisition [Line Items]
Finite-lived intangible asset, useful life	10 years
Customer Relationships [Member]
Business Acquisition [Line Items]
Finite-lived intangible asset, useful life	10 years