Commitments and Contingencies - Litigation (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended	12 Months Ended				9 Months Ended
	Jun. 30, 2013 Resolved Litigation [Member] Sintel [Member]	Sep. 30, 2013 Resolved Litigation [Member] Sintel [Member]	Dec. 31, 2012 Pending Litigation [Member] Sintel [Member]	Sep. 30, 2013 Pending Litigation [Member] Sunlight Entities Somerset [Member]	Sep. 30, 2013 Pending Litigation [Member] Sunlight Entities Morris [Member]	Sep. 30, 2013 Pending Litigation [Member] Sunlight Entities Sussex [Member]	Sep. 30, 2013 Pending Litigation [Member] City Of Marathon [Member]	Sep. 30, 2013 Pending Litigation [Member] City Of Marathon [Member] Minimum [Member]
Commitments and Contingencies [Line Items]
Legal proceeding, plaintiff		The labor union representing the workers of Sistemas e Instalaciones de Telecomunicacion S.A. (“Sintel”)					The Company
Litigation, settlement agreement, terms		On June 17, 2013, MasTec, the workers and the prosecutor resolved the matter, resulting in the dismissal all of the charges and claims brought against MasTec and the MasTec defendants. The workers provided MasTec and MasTec defendants with a release and an acknowledgment that MasTec and MasTec defendants acted in good faith and did not cause Sintel's bankruptcy. On June 20, 2013, the Audiencia Nacional issued an order dismissing the charges and claims against MasTec and the MasTec defendants and finding another party guilty and liable of certain charges.
Litigation, date of dismissal		Jun. 20, 2013
Pending or threatened litigation, loss in period	$ 2.8		$ 9.6
Contract price, pending litigation				29	36	26
Damages sought								$ 6