Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Antidilution

-URI http://asc.fasb.org/extlink&oid=6505113

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Diluted Earnings Per Share

-URI http://asc.fasb.org/extlink&oid=6510752

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Contingent Stock Agreement

-URI http://asc.fasb.org/extlink&oid=6508534

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 260

-SubTopic 10

-Section 50

-Paragraph 1

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

+ Details

Name:	us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of shares issued in exchange for the original debt being converted in a noncash (or part noncash) transaction. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or payments in the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 50

-Paragraph 5

-URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4332-108586

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 50

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4304-108586

+ Details

Name:	us-gaap_DebtConversionConvertedInstrumentSharesIssued1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

The price per share of the conversion feature embedded in the debt instrument.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 470

-SubTopic 20

-Section 50

-Paragraph 5

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6928298&loc=SL6031898-161870

+ Details

Name:	us-gaap_DebtInstrumentConvertibleConversionPrice1
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ 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 210.5-02.22(a)(1))

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

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
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

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

- Definition

Gross amount of debt extinguished.

+ References

No definition available.

+ Details

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

- Definition

Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of contingently issuable shares. Contingently issuable shares are those shares that are issuable for little or no cash contingent on certain conditions being met.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 260

-SubTopic 10

-Section 45

-Paragraph 55

-URI http://asc.fasb.org/extlink&oid=7655603&loc=d3e2626-109256

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 260

-SubTopic 10

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 260

-SubTopic 10

-Section 45

-Paragraph 48

-URI http://asc.fasb.org/extlink&oid=7655603&loc=d3e2538-109256

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Contingently Issuable Shares

-URI http://asc.fasb.org/extlink&oid=6508586

+ Details

Name:	us-gaap_IncrementalCommonSharesAttributableToContingentlyIssuableShares
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

The cash outflow from the repayment of a long-term debt instrument which can be exchanged for a specified amount of another security, typically the entity's common stock, at the option of the issuer or the holder.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Financing Activities

-URI http://asc.fasb.org/extlink&oid=6513228

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 15

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3291-108585

+ Details

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

- Details

Name:	us-gaap_DebtConversionByUniqueDescriptionAxis=mtz_A4.0NotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtConversionByUniqueDescriptionAxis=mtz_A20114.0NotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtConversionByUniqueDescriptionAxis=mtz_A20094.0NotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtConversionByUniqueDescriptionAxis=mtz_A4.25NotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtConversionByUniqueDescriptionAxis=mtz_A20114.25NotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtConversionByUniqueDescriptionAxis=mtz_A20094.25NotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_ConvertibleDebtMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=mtz_A20114.0NotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementEquityComponentsAxis=us-gaap_CommonStockMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis=mtz_CommonStockEquivalentsExcludedDueToNetLossMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Earnings Per Share (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended		3 Months Ended		6 Months Ended
	Dec. 31, 2014	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
4.0% Convertible Notes [Member]
Earnings Per Share [Line Items]
Debt instrument, convertible, repayments (in dollars)		$ 105
Debt instrument, convertible, conversion price per share (in dollars per share)		$ 15.76		$ 15.76		$ 15.76
2011 4.0% Notes [Member]
Earnings Per Share [Line Items]
Debt instrument, convertible, conversion price per share (in dollars per share)		15.76		15.76		15.76
2009 4.0% Notes [Member]
Earnings Per Share [Line Items]
Debt instrument, convertible, conversion price per share (in dollars per share)		$ 15.76		$ 15.76		$ 15.76
4.25% Convertible Notes [Member]
Earnings Per Share [Line Items]
Debt instrument, convertible, repayments (in dollars)	$ 97
Debt instrument, convertible, conversion price per share (in dollars per share)	$ 15.48
2011 4.25% Notes [Member]
Earnings Per Share [Line Items]
Debt instrument, convertible, conversion price per share (in dollars per share)	15.48
2009 4.25% Notes [Member]
Earnings Per Share [Line Items]
Debt instrument, convertible, conversion price per share (in dollars per share)	$ 15.48
Convertible Debt [Member]
Earnings Per Share [Line Items]
Premium shares (in shares)			0	7,711,000	0	8,066,000
Convertible Debt [Member] \| 2011 4.0% Notes [Member]
Earnings Per Share [Line Items]
Premium shares (in shares)				3,300,000		3,600,000
Convertible Debt [Member] \| 4.0% Convertible Notes [Member]
Earnings Per Share [Line Items]
Debt instrument, convertible, matured and converted (in dollars)		$ 115
Debt instrument, convertible, interest rate (percentage)		4.00%		4.00%		4.00%
Convertible Debt [Member] \| 2011 4.0% Notes [Member]
Earnings Per Share [Line Items]
Debt instrument, convertible, matured and converted (in dollars)		$ 105
Debt instrument, convertible, interest rate (percentage)		4.00%		4.00%		4.00%
Convertible Debt [Member] \| 2009 4.0% Notes [Member]
Earnings Per Share [Line Items]
Debt instrument, convertible, matured and converted (in dollars)		$ 10
Debt instrument, convertible, interest rate (percentage)		4.00%		4.00%		4.00%
Convertible Debt [Member] \| 4.25% Convertible Notes [Member]
Earnings Per Share [Line Items]
Debt instrument, convertible, matured and converted (in dollars)	$ 100
Debt instrument, convertible, interest rate (percentage)	4.25%
Convertible Debt [Member] \| 2011 4.25% Notes [Member]
Earnings Per Share [Line Items]
Debt instrument, convertible, matured and converted (in dollars)	$ 97
Debt instrument, convertible, interest rate (percentage)	4.25%
Convertible Debt [Member] \| 2009 4.25% Notes [Member]
Earnings Per Share [Line Items]
Debt instrument, convertible, matured and converted (in dollars)	$ 3
Debt instrument, convertible, interest rate (percentage)	4.25%
Common Stock [Member]
Earnings Per Share [Line Items]
Weighted average anti-dilutive common stock equivalents (in shares)			476,769	304,600	495,181	182,218
Common Stock [Member] \| 4.0% Convertible Notes [Member]
Earnings Per Share [Line Items]
Debt instrument, convertible, common shares issued (in shares)		4,200,000
Common Stock [Member] \| 4.25% Convertible Notes [Member]
Earnings Per Share [Line Items]
Debt instrument, convertible, common shares issued (in shares)	2,400,000
Common Stock [Member] \| Common Stock Equivalents Excluded Due To Net Loss [Member]
Earnings Per Share [Line Items]
Weighted average anti-dilutive common stock equivalents (in shares)			476,769		495,181