Supplemental Guarantor Financial Information (Condensed Unaudited Consolidating Balance Sheets) (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017
Assets
Total current assets	$ 2,127,012		$ 2,168,989
Property and equipment, net	852,804		747,808
Operating lease assets	241,493		0
Goodwill and other intangible assets, net	1,334,400		1,269,700
Investments in and advances to consolidated affiliates, net	0		0
Other long-term assets	241,737		253,436
Total assets	4,797,371		4,439,953
Liabilities and equity
Total current liabilities	1,391,153		1,283,611
Long-term debt, including finance leases	1,250,812		1,324,223
Long-term operating lease liabilities	168,698		0
Other long-term liabilities	435,300		440,100
Total liabilities	3,246,033		3,047,929
Total equity	1,551,338	$ 1,433,732	1,392,024	$ 1,430,398	$ 1,374,197	$ 1,433,353
Total liabilities and equity	4,797,371		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	1,530,400		1,373,100
Other long-term assets	17,700		16,800
Total assets	1,548,100		1,389,900
Liabilities and equity
Total current liabilities	0		0
Long-term debt, including finance leases	0		0
Long-term operating lease liabilities	0
Other long-term liabilities	0		0
Total liabilities	0		0
Total equity	1,548,100		1,389,900
Total liabilities and equity	1,548,100		1,389,900
Reportable Legal Entities [Member] | Guarantor Subsidiaries [Member]
Assets
Total current assets	1,949,100		1,993,000
Property and equipment, net	810,900		699,200
Operating lease assets	223,900
Goodwill and other intangible assets, net	1,251,700		1,188,000
Investments in and advances to consolidated affiliates, net	1,111,600		1,138,400
Other long-term assets	38,200		42,000
Total assets	5,385,400		5,060,600
Liabilities and equity
Total current liabilities	1,328,000		1,185,900
Long-term debt, including finance leases	1,245,500		1,319,400
Long-term operating lease liabilities	155,000
Other long-term liabilities	425,400		429,200
Total liabilities	3,153,900		2,934,500
Total equity	2,231,500		2,126,100
Total liabilities and equity	5,385,400		5,060,600
Reportable Legal Entities [Member] | Non-Guarantor Subsidiaries [Member]
Assets
Total current assets	244,000		248,500
Property and equipment, net	41,900		48,600
Operating lease assets	17,600
Goodwill and other intangible assets, net	82,600		81,700
Investments in and advances to consolidated affiliates, net	849,000		816,900
Other long-term assets	185,800		194,600
Total assets	1,420,900		1,390,300
Liabilities and equity
Total current liabilities	129,200		170,200
Long-term debt, including finance leases	5,300		4,900
Long-term operating lease liabilities	13,700
Other long-term liabilities	10,000		10,800
Total liabilities	158,200		185,900
Total equity	1,262,700		1,204,400
Total liabilities and equity	1,420,900		1,390,300
Eliminations [Member]
Assets
Total current assets	(66,100)		(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	(3,491,000)		(3,328,400)
Other long-term assets	0		0
Total assets	(3,557,100)		(3,400,900)
Liabilities and equity
Total current liabilities	(66,100)		(72,500)
Long-term debt, including finance leases	0		0
Long-term operating lease liabilities	0
Other long-term liabilities	0		0
Total liabilities	(66,100)		(72,500)
Total equity	(3,491,000)		(3,328,400)
Total liabilities and equity	$ (3,557,100)		$ (3,400,900)