Stock-Based Compensation and Other Employee Benefit Plans (Deferred Compensation Plans) (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Deferred Compensation Arrangements [Abstract]
Deferred compensation plans, description	MasTec offers a deferred compensation plan to its highly compensated employees. These employees are allowed to contribute a percentage of their pre-tax annual compensation to the deferred compensation plan. The Company also offers a deferred compensation plan to its Board of Directors, under which directors may elect to defer the receipt of compensation for their services.
Deferred compensation plans, assets	$ 9.4	$ 7.7
Deferred compensation plans, liabilities	$ 9.7	$ 7.6

No definition available.

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- Definition

General description of deferred compensation arrangements. Deferred compensation represents currently earned compensation that, under the terms of a profit-sharing, rabbi trust, pension, employee contract, or equity-based (including stock or unit option) plan, is not actually paid until a later date and is therefore not taxable until that date. May also include some split-dollar life insurance arrangements. This type of arrangement is usually made to help employees postpone paying taxes on the income and also to retain employees longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5047-113901

+ Details

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- Definition

Aggregate carrying value as of the balance sheet date of the liabilities for all deferred compensation arrangements payable beyond one year (or the operating cycle, if longer).

+ References

No definition available.

+ Details

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- Definition

Carrying amount as of the balance sheet date of assets held under deferred compensation agreements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.17)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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