Supplemental Guarantor Financial Information (Condensed Consolidating Balance Sheets) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Assets
Total current assets	$ 2,173,559	$ 2,168,989
Property and equipment, net	905,835	747,808
Operating lease assets	229,903	0
Goodwill and other intangible assets, net	1,433,000	1,269,700
Investments in and advances to consolidated affiliates, net	0	0
Other long-term assets	254,741	253,436
Total assets	4,997,006	4,439,953	$ 4,066,600
Liabilities and equity
Total current liabilities	1,219,126	1,283,611
Long-term debt, including finance leases	1,314,030	1,324,223
Advances from consolidated affiliates, net	0
Long-term operating lease liabilities	154,553	0
Other long-term liabilities	517,600	440,100
Total liabilities	3,205,315	3,047,929
Total equity	1,791,691	1,392,024	$ 1,433,353	$ 1,103,634
Total liabilities and equity	4,997,006	4,439,953
Reportable Legal Entities [Member] | MasTec, Inc. [Member]
Assets
Total current assets	0	0
Property and equipment, net	0	0
Operating lease assets	0
Goodwill and other intangible assets, net	0	0
Investments in and advances to consolidated affiliates, net	1,768,900	1,373,100
Other long-term assets	18,400	16,800
Total assets	1,787,300	1,389,900
Liabilities and equity
Total current liabilities	100	0
Long-term debt, including finance leases	0	0
Advances from consolidated affiliates, net	0
Long-term operating lease liabilities	0
Other long-term liabilities	0	0
Total liabilities	100	0
Total equity	1,787,200	1,389,900
Total liabilities and equity	1,787,300	1,389,900
Reportable Legal Entities [Member] | Guarantor Subsidiaries [Member]
Assets
Total current assets	1,987,800	1,993,000
Property and equipment, net	862,000	699,200
Operating lease assets	214,700
Goodwill and other intangible assets, net	1,265,600	1,188,000
Investments in and advances to consolidated affiliates, net	1,233,500	1,138,400
Other long-term assets	42,600	42,000
Total assets	5,606,200	5,060,600
Liabilities and equity
Total current liabilities	1,141,600	1,185,900
Long-term debt, including finance leases	1,310,900	1,319,400
Advances from consolidated affiliates, net	0
Long-term operating lease liabilities	143,000
Other long-term liabilities	493,100	429,200
Total liabilities	3,088,600	2,934,500
Total equity	2,517,600	2,126,100
Total liabilities and equity	5,606,200	5,060,600
Reportable Legal Entities [Member] | Non-Guarantor Subsidiaries [Member]
Assets
Total current assets	248,100	248,500
Property and equipment, net	43,900	48,600
Operating lease assets	15,200
Goodwill and other intangible assets, net	167,300	81,700
Investments in and advances to consolidated affiliates, net	0	816,900
Other long-term assets	193,800	194,600
Total assets	668,300	1,390,300
Liabilities and equity
Total current liabilities	139,800	170,200
Long-term debt, including finance leases	3,100	4,900
Advances from consolidated affiliates, net	167,500
Long-term operating lease liabilities	11,600
Other long-term liabilities	24,500	10,800
Total liabilities	346,500	185,900
Total equity	321,800	1,204,400
Total liabilities and equity	668,300	1,390,300
Eliminations [Member]
Assets
Total current assets	(62,400)	(72,500)
Property and equipment, net	0	0
Operating lease assets	0
Goodwill and other intangible assets, net	0	0
Investments in and advances to consolidated affiliates, net	(3,002,400)	(3,328,400)
Other long-term assets	0	0
Total assets	(3,064,800)	(3,400,900)
Liabilities and equity
Total current liabilities	(62,400)	(72,500)
Long-term debt, including finance leases	0	0
Advances from consolidated affiliates, net	(167,500)
Long-term operating lease liabilities	0
Other long-term liabilities	0	0
Total liabilities	(229,900)	(72,500)
Total equity	(2,834,900)	(3,328,400)
Total liabilities and equity	$ (3,064,800)	$ (3,400,900)