Earnings Per Share (Schedule of Earnings Per Share Information) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Net income attributable to MasTec:
Net income - basic (in dollars)	$ 113,100	$ 116,500	$ 57,000	$ 36,200	$ 100,900	$ 128,600	$ 119,700	$ 43,100	$ 322,848	$ 392,334	$ 259,659
Net income - diluted (in dollars)									$ 322,848	$ 392,334	$ 259,659
Weighted average shares outstanding:
Weighted average shares outstanding - basic									72,799,000	75,185,000	78,695,000
Dilutive common stock equivalents (in shares)									916,000	661,000	1,077,000
Weighted average shares outstanding - diluted									73,715,000	75,846,000	79,772,000
Anti-dilutive common stock (in shares)									43,989