Supplemental Guarantor Financial Information (Condensed Unaudited Consolidating Balance Sheets) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Assets
Total current assets	$ 2,668,962	$ 1,852,366
Property and equipment, net	736,447	706,506
Goodwill and other intangible assets, net	1,327,000	1,328,900
Investments in and advances to consolidated affiliates, net	0	0
Other long-term assets	242,391	178,824
Total assets	4,974,806	4,066,576
Liabilities and equity
Total current liabilities	1,372,497	963,827
Long-term debt	1,688,820	1,280,706
Other long-term liabilities	423,700	388,700
Total liabilities	3,484,986	2,633,223
Total equity	1,489,820	1,433,353
Total liabilities and equity	4,974,806	4,066,576
Reportable Legal Entities [Member] | MasTec, Inc. [Member]
Assets
Total current assets	0	0
Property and equipment, net	0	0
Goodwill and other intangible assets, net	0	0
Investments in and advances to consolidated affiliates, net	1,470,700	1,415,000
Other long-term assets	16,900	15,800
Total assets	1,487,600	1,430,800
Liabilities and equity
Total current liabilities	0	0
Long-term debt	0	0
Other long-term liabilities	0	0
Total liabilities	0	0
Total equity	1,487,600	1,430,800
Total liabilities and equity	1,487,600	1,430,800
Reportable Legal Entities [Member] | Guarantor Subsidiaries [Member]
Assets
Total current assets	2,524,600	1,536,600
Property and equipment, net	687,500	638,700
Goodwill and other intangible assets, net	1,191,600	1,187,900
Investments in and advances to consolidated affiliates, net	1,007,500	847,700
Other long-term assets	35,000	23,400
Total assets	5,446,200	4,234,300
Liabilities and equity
Total current liabilities	1,365,100	778,600
Long-term debt	1,677,800	1,269,400
Other long-term liabilities	411,500	379,900
Total liabilities	3,454,400	2,427,900
Total equity	1,991,800	1,806,400
Total liabilities and equity	5,446,200	4,234,300
Reportable Legal Entities [Member] | Non-Guarantor Subsidiaries [Member]
Assets
Total current assets	287,900	332,900
Property and equipment, net	48,900	67,800
Goodwill and other intangible assets, net	135,400	141,000
Investments in and advances to consolidated affiliates, net	823,600	746,600
Other long-term assets	190,500	139,600
Total assets	1,486,300	1,427,900
Liabilities and equity
Total current liabilities	150,900	202,300
Long-term debt	11,000	11,300
Other long-term liabilities	12,200	8,800
Total liabilities	174,100	222,400
Total equity	1,312,200	1,205,500
Total liabilities and equity	1,486,300	1,427,900
Eliminations [Member]
Assets
Total current assets	(143,500)	(17,100)
Property and equipment, net	0	0
Goodwill and other intangible assets, net	0	0
Investments in and advances to consolidated affiliates, net	(3,301,800)	(3,009,300)
Other long-term assets	0	0
Total assets	(3,445,300)	(3,026,400)
Liabilities and equity
Total current liabilities	(143,500)	(17,100)
Long-term debt	0	0
Other long-term liabilities	0	0
Total liabilities	(143,500)	(17,100)
Total equity	(3,301,800)	(3,009,300)
Total liabilities and equity	$ (3,445,300)	$ (3,026,400)