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Commitments and Contingencies (Investment Arrangements) (Narrative) (Details) - Proportionately Consolidated Non-Controlled Joint Venture [Member] | Dec. 31, 2020
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Joint Ventures That Provide Electrical Transmission Infrastructure Services [Member] | Minimum [Member] |
Other Commitments [Line Items] |
Proportionately consolidated non-controlled joint venture, ownership percentage | 85.00%
Joint Ventures That Provide Electrical Transmission Infrastructure Services [Member] | Maximum [Member] |
Other Commitments [Line Items] |
Proportionately consolidated non-controlled joint venture, ownership percentage | 90.00%
Joint Venture Civil Construction Project [Member] |
Other Commitments [Line Items] |
Proportionately consolidated non-controlled joint venture, ownership percentage | 50.00%

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- Definition The percentage interest in a proportionately consolidated joint venture. + References No definition available. + Details
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Namespace Prefix: | mtz_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

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

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- Details
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Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
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Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
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Balance Type: |
Period Type: |

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- Details
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Namespace Prefix: |
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Period Type: |

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- Details
Name: | srt_OwnershipAxis=mtz_JointVentureCivilConstructionProjectMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |