Other Retirement Plans (Narrative) (Details)	9 Months Ended
Sep. 30, 2018
Multiemployer Plans [Abstract]
Multiemployer plans, general nature	Certain of MasTec’s subsidiaries, including certain subsidiaries in Canada, contribute amounts to multiemployer pension and other multiemployer benefit plans and trusts (“MEPPs”), which are recorded as a component of employee wages and salaries within costs of revenue, excluding depreciation and amortization. Contributions are generally based on fixed amounts per hour per employee for employees covered under these plans. Multiemployer plan contribution rates are determined annually and assessed on a “pay-as-you-go” basis based on union employee payrolls.

Description of the general nature of multiemployer plans and of the employer's participation in those plans that would indicate how the risks of participating in these plans are different from single-employer plans. A multiemployer plan is a pension or postretirement benefit plan to which two or more unrelated employers contribute where assets contributed by one participating employer may be used to provide benefits to employees of other participating employers.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 80
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=65877416&loc=SL14450655-114947

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