Supplemental Guarantor Financial Information (Condensed Consolidating Balance Sheets (Unaudited)) (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Assets
Total current assets	$ 2,079,779	$ 2,173,559
Property and equipment, net	937,309	905,835
Operating lease assets	210,637	229,903
Goodwill and other intangible assets, net	1,421,900	1,433,000
Investments in and advances to consolidated affiliates, net	0	0
Other long-term assets	243,888	254,741
Total assets	4,893,548	4,997,006
Liabilities and equity
Total current liabilities	1,260,033	1,219,126
Long-term debt, including finance leases	1,297,342	1,314,030
Advances from consolidated affiliates, net	0	0
Long-term operating lease liabilities	143,441	154,553
Other long-term liabilities	502,900	517,600
Total liabilities	3,203,735	3,205,315
Total equity	1,689,813	1,791,691	$ 1,433,732	$ 1,392,024
Total liabilities and equity	4,893,548	4,997,006
Reportable Legal Entities [Member] | MasTec, Inc. [Member]
Assets
Total current assets	0	0
Property and equipment, net	0	0
Operating lease assets	0	0
Goodwill and other intangible assets, net	0	0
Investments in and advances to consolidated affiliates, net	1,667,200	1,768,900
Other long-term assets	18,300	18,400
Total assets	1,685,500	1,787,300
Liabilities and equity
Total current liabilities	0	100
Long-term debt, including finance leases	0	0
Advances from consolidated affiliates, net	0	0
Long-term operating lease liabilities	0	0
Other long-term liabilities	0	0
Total liabilities	0	100
Total equity	1,685,500	1,787,200
Total liabilities and equity	1,685,500	1,787,300
Reportable Legal Entities [Member] | Guarantor Subsidiaries [Member]
Assets
Total current assets	1,871,600	1,987,800
Property and equipment, net	898,800	862,000
Operating lease assets	201,300	214,700
Goodwill and other intangible assets, net	1,260,400	1,265,600
Investments in and advances to consolidated affiliates, net	1,382,700	1,233,500
Other long-term assets	39,600	42,600
Total assets	5,654,400	5,606,200
Liabilities and equity
Total current liabilities	1,205,600	1,141,600
Long-term debt, including finance leases	1,294,900	1,310,900
Advances from consolidated affiliates, net	0	0
Long-term operating lease liabilities	131,700	143,000
Other long-term liabilities	482,400	493,100
Total liabilities	3,114,600	3,088,600
Total equity	2,539,800	2,517,600
Total liabilities and equity	5,654,400	5,606,200
Reportable Legal Entities [Member] | Non-Guarantor Subsidiaries [Member]
Assets
Total current assets	236,500	248,100
Property and equipment, net	38,500	43,900
Operating lease assets	9,300	15,200
Goodwill and other intangible assets, net	161,500	167,300
Investments in and advances to consolidated affiliates, net	0	0
Other long-term assets	186,000	193,800
Total assets	631,800	668,300
Liabilities and equity
Total current liabilities	82,700	139,800
Long-term debt, including finance leases	2,400	3,100
Advances from consolidated affiliates, net	199,300	167,500
Long-term operating lease liabilities	11,700	11,600
Other long-term liabilities	20,500	24,500
Total liabilities	316,600	346,500
Total equity	315,200	321,800
Total liabilities and equity	631,800	668,300
Eliminations [Member]
Assets
Total current assets	(28,300)	(62,400)
Property and equipment, net	0	0
Operating lease assets	0	0
Goodwill and other intangible assets, net	0	0
Investments in and advances to consolidated affiliates, net	(3,049,900)	(3,002,400)
Other long-term assets	0	0
Total assets	(3,078,200)	(3,064,800)
Liabilities and equity
Total current liabilities	(28,300)	(62,400)
Long-term debt, including finance leases	0	0
Advances from consolidated affiliates, net	(199,300)	(167,500)
Long-term operating lease liabilities	0	0
Other long-term liabilities	0	0
Total liabilities	(227,600)	(229,900)
Total equity	(2,850,600)	(2,834,900)
Total liabilities and equity	$ (3,078,200)	$ (3,064,800)