Supplemental Guarantor Financial Information (Condensed Unaudited Consolidating Balance Sheets) (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Assets
Total current assets	$ 2,262,059	$ 2,168,989
Property and equipment, net	799,479	747,808
Operating lease assets	223,106	0
Goodwill and other intangible assets, net	1,333,700	1,269,700
Investments in and advances to consolidated affiliates, net	0	0
Other long-term assets	242,039	253,436
Total assets	4,860,393	4,439,953
Liabilities and equity
Total current liabilities	1,262,652	1,283,611
Long-term debt, including finance leases	1,539,294	1,324,223
Long-term operating lease liabilities	153,850	0
Other long-term liabilities	470,900	440,100
Total liabilities	3,426,661	3,047,929
Total equity	1,433,732	1,392,024	$ 1,374,197	$ 1,433,353
Total liabilities and equity	4,860,393	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	1,414,700	1,373,100
Other long-term assets	16,900	16,800
Total assets	1,431,600	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	1,431,600	1,389,900
Total liabilities and equity	1,431,600	1,389,900
Reportable Legal Entities [Member] | Guarantor Subsidiaries [Member]
Assets
Total current assets	2,046,300	1,993,000
Property and equipment, net	756,600	699,200
Operating lease assets	205,200
Goodwill and other intangible assets, net	1,251,500	1,188,000
Investments in and advances to consolidated affiliates, net	1,166,300	1,138,400
Other long-term assets	35,200	42,000
Total assets	5,461,100	5,060,600
Liabilities and equity
Total current liabilities	1,169,300	1,185,900
Long-term debt, including finance leases	1,534,700	1,319,400
Long-term operating lease liabilities	139,900
Other long-term liabilities	459,700	429,200
Total liabilities	3,303,600	2,934,500
Total equity	2,157,500	2,126,100
Total liabilities and equity	5,461,100	5,060,600
Reportable Legal Entities [Member] | Non-Guarantor Subsidiaries [Member]
Assets
Total current assets	278,900	248,500
Property and equipment, net	42,900	48,600
Operating lease assets	17,900
Goodwill and other intangible assets, net	82,200	81,700
Investments in and advances to consolidated affiliates, net	791,000	816,900
Other long-term assets	189,800	194,600
Total assets	1,402,700	1,390,300
Liabilities and equity
Total current liabilities	156,400	170,200
Long-term debt, including finance leases	4,600	4,900
Long-term operating lease liabilities	14,000
Other long-term liabilities	11,100	10,800
Total liabilities	186,100	185,900
Total equity	1,216,600	1,204,400
Total liabilities and equity	1,402,700	1,390,300
Eliminations [Member]
Assets
Total current assets	(63,100)	(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	(3,372,000)	(3,328,400)
Other long-term assets	0	0
Total assets	(3,435,100)	(3,400,900)
Liabilities and equity
Total current liabilities	(63,100)	(72,500)
Long-term debt, including finance leases	0	0
Long-term operating lease liabilities	0
Other long-term liabilities	0	0
Total liabilities	(63,100)	(72,500)
Total equity	(3,372,000)	(3,328,400)
Total liabilities and equity	$ (3,435,100)	$ (3,400,900)