Number of joint ventures in which the Company has an interest.

No definition available.

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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_
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- Definition

Costs incurred and are directly related to generating contract revenues.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.2(e))
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

+ Details

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Period Type:	duration

- Definition

Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=82913245&loc=d3e12069-110248

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- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

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Balance Type:	credit
Period Type:	instant

- 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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- Definition

The fair value, as of the date of each statement of financial position presented, of other assets which are owned but transferred to serve as collateral for the payment of the related debt obligation, and that are reclassified and separately reported in the statement of financial position because the transferee has the right by contract or custom to sell or re-pledge them.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=66007379&loc=d3e113888-111728

+ Details

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Period Type:	instant

- Definition

Carrying amount (including both current and noncurrent portions) of accrued known and estimated losses incurred as of the balance sheet date for which no insurance coverage exists, and for which a claim has been made or is probable of being asserted, typically arising from workmen's compensation-type of incidents and personal injury to nonemployees from accidents on the entity's property.

+ 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 210.5-02.24)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

Carrying amount of accrued known and estimated losses incurred as of the balance sheet date for which no insurance coverage exists, and for which a claim has been made or is probable of being asserted, typically arising from workmen's compensation-type of incidents and personal injury to nonemployees from accidents on the entity's property that are expected to be paid after one year (or the normal operating cycle, if longer).

+ References

No definition available.

+ Details

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Commitments and Contingencies (Other Commitments and Contingencies) (Narrative) (Details) CAD in Millions, $ in Millions	Jun. 30, 2017 USD ($)	Dec. 31, 2016 USD ($)	Jun. 30, 2017 CAD	Jun. 30, 2017 USD ($)	Dec. 31, 2016 CAD	Dec. 31, 2016 USD ($)
Self-Insurance [Member] \| Workers Compensation, General and Automobile Policies [Member]
Commitments and Contingencies [Line Items]
Self-insurance reserve				$ 94.2		$ 85.8
Self-Insurance [Member] \| Workers Compensation, General and Automobile Policies [Member] \| Other Long-Term Liabilities [Member]
Commitments and Contingencies [Line Items]
Self-insurance reserve, non-current				59.5		55.2
Self-Insurance [Member] \| Workers Compensation, General and Automobile Policies [Member] \| Other Long-Term Assets [Member] \| Cash [Member]
Commitments and Contingencies [Line Items]
Cash collateral deposited with insurance carriers				1.5		1.5
Self-Insurance [Member] \| Employee Group Medical Claims Policies [Member]
Commitments and Contingencies [Line Items]
Self-insurance reserve				$ 3.0		2.6
Joint Ventures [Member] \| Joint Venture A That Provides Electrical Transmission Infrastructure Services [Member]
Commitments and Contingencies [Line Items]
Proportionately consolidated non-controlled joint venture, ownership percentage			85.00%	85.00%
Joint Ventures [Member] \| Joint Venture B That Provides Electrical Transmission Infrastructure Services [Member]
Commitments and Contingencies [Line Items]
Proportionately consolidated non-controlled joint venture, ownership percentage			85.00%	85.00%
Joint Ventures [Member] \| Joint Venture C That Provides Electrical Transmission Infrastructure Services [Member]
Commitments and Contingencies [Line Items]
Proportionately consolidated non-controlled joint venture, ownership percentage			90.00%	90.00%
Joint Ventures [Member] \| Joint Ventures That Provide Infrastructure Construction Services For Electrical Transmission Projects [Member]
Commitments and Contingencies [Line Items]
Number of joint ventures			3	3
Joint Ventures [Member] \| Pacer [Member]
Commitments and Contingencies [Line Items]
Proportionately consolidated non-controlled joint venture, ownership percentage			35.00%	35.00%
Performance and Payment Bonds [Member]
Commitments and Contingencies [Line Items]
Outstanding bonds, amount				$ 50.9		72.9
Performance and Payment Bonds [Member] \| Joint Ventures [Member] \| Pacer [Member]
Commitments and Contingencies [Line Items]
Outstanding bonds, amount \| CAD			CAD 132.1		CAD 132.1
Performance and Payment Bonds [Member] \| Estimate [Member]
Commitments and Contingencies [Line Items]
Bonded projects, costs to complete	$ 9.6	$ 9.5
Surety Bond [Member] \| Self-Insurance [Member] \| Workers Compensation [Member]
Commitments and Contingencies [Line Items]
Outstanding bonds, amount				13.5		13.5
Credit Facility [Member]
Commitments and Contingencies [Line Items]
Letters of credit issued				305.6		314.3
Credit Facility [Member] \| Financial Guarantees [Member] \| Self-Insurance [Member] \| Workers Compensation, General and Automobile Policies [Member]
Commitments and Contingencies [Line Items]
Letters of credit issued				$ 85.1		$ 85.1