Number of persons from management with an ownership interest in the related party entity

No definition available.

Name:	mtz_NumberOfManagementMembers
Namespace Prefix:	mtz_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount for accounts payable to related parties.

+ References

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+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

For an unclassified balance sheet, amount of receivables arising from transactions with related parties.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Expenses recognized resulting from transactions (excluding transactions that are eliminated in consolidated or combined financial statements) with related party.

+ References

+ Details

Name:	us-gaap_RelatedPartyTransactionExpensesFromTransactionsWithRelatedParty
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_RelatedPartyTransactionLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Reflects the sum of all other revenue and income realized from sales and other transactions (excluding transactions that are eliminated in consolidated or combined financial statements) with related party during the period.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of revenue, fees and commissions earned from transactions between (a) a parent company and its subsidiaries; (b) subsidiaries of a common parent; (c) an entity and trusts for the benefit of employees, for example, but not limited to, pension and profit-sharing trusts that are managed by or under the trusteeship of the entity's management; (d) an entity and its principal, owners, management, or members of their immediate families; and (e) affiliates.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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-Topic 946
-SubTopic 220
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+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=srt_ManagementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=mtz_SubcontractingArrangementsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=srt_BoardOfDirectorsChairmanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=us-gaap_LeaseAgreementsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=srt_ExecutiveOfficerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_MajorCustomersAxis=mtz_RelatedCustomerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=mtz_ConstructionServicesMember
Namespace Prefix:
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Balance Type:
Period Type:

Related Party Transactions (Executive Officers) (Narrative) (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020 USD ($) numberOfEmployees	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) numberOfEmployees	Sep. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)
Management [Member] \| Subcontracting Arrangements [Member]
Related Party Transaction [Line Items]
Number of management members, subcontracting arrangement \| numberOfEmployees	2		2
Payments or expenses, related party	$ 0.0	$ 3.1	$ 0.6	$ 9.3
Payables, related party	0.1		0.1		$ 0.2
Chairman, Board of Directors [Member] \| Lease Agreements [Member]
Related Party Transaction [Line Items]
Payments or expenses, related party	0.6	0.6	1.9	2.0
Executive Officers [Member] \| Related Customer [Member]
Related Party Transaction [Line Items]
Receivables, related party	1.0		1.0		0.8
Charges, related party	0.3	0.3	1.0	1.1
Executive Officers [Member] \| Construction Services [Member]
Related Party Transaction [Line Items]
Payments or expenses, related party			0.2
Revenue, related party	0.7	$ 5.2	6.2	$ 7.4
Receivables, related party	$ 0.7		$ 0.7		$ 3.9