Stock-Based Compensation and Other Employee Benefit Plans (Narrative) (Details)	12 Months Ended
	Dec. 31, 2017 shares
Common Stock [Member]
Stock-Based Compensation and Other Employee Benefit Plans [Line Items]
Stock-based compensation, number of shares available for grant or issuance	4,811,000
Employee Stock Purchase Plans [Member]
Stock-Based Compensation and Other Employee Benefit Plans [Line Items]
Stock-based compensation plan, description	The Company has certain employee stock purchase plans under which shares of the Company’s common stock are available for purchase by eligible employees. These plans allow qualified employees to purchase MasTec, Inc. common stock at 85% of its fair market value at the lower of (i) the date of commencement of the offering period or (ii) the last day of the exercise period, as defined in the plan documents.
2013 Incentive Plan [Member] | Restricted Shares [Member]
Stock-Based Compensation and Other Employee Benefit Plans [Line Items]
Stock-based compensation plan, description	The 2013 Incentive Plan permits a total of approximately 7,391,000 shares of the Company’s common stock to be issued.
2013 Incentive Plan [Member] | Restricted Shares [Member] | Common Stock [Member]
Stock-Based Compensation and Other Employee Benefit Plans [Line Items]
Stock-based compensation plan, number of shares authorized	7,391,000
ESPPs [Member] | Employee Stock Purchase Plans [Member]
Stock-Based Compensation and Other Employee Benefit Plans [Line Items]
Stock-based compensation plan, description	Under the Company’s ESPPs, shares of the Company’s common stock are available for purchase by eligible employees, which collectively permit the issuance of up to 3,000,000 new shares of MasTec, Inc. common stock.
ESPPs [Member] | Employee Stock Purchase Plans [Member] | Common Stock [Member]
Stock-Based Compensation and Other Employee Benefit Plans [Line Items]
Stock-based compensation plan, number of shares authorized	3,000,000