Represents the amount of the letters of credit related to contract performance obligations.

No definition available.

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- Definition

Represents the letters of credit outstanding related to the payment obligation under insurance programs.

+ References

No definition available.

+ Details

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Namespace Prefix:	myrg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the number of irrevocable standby letters of credit outstanding.

+ References

No definition available.

+ Details

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Data Type:	xbrli:integerItemType
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- Definition

Represents the number of letters of credit related to the payment obligation under insurance programs.

+ References

No definition available.

+ Details

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- Details

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- Definition

Represents the term of the operating lease arrangements of the entity.

+ References

No definition available.

+ Details

Name:	myrg_OperatingLeaseTerm
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Data Type:	xbrli:durationItemType
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- Details

Name:	myrg_PurchaseCommitmentsAbstract
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Data Type:	xbrli:stringItemType
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Period Type:	duration

- Definition

Represents the schedule period of time for cash outlay requirements under an existing purchase commitment.

+ References

No definition available.

+ Details

Name:	myrg_SignificantPurchaseCommitmentScheduledPeriodOfTimeForCashOutlay
Namespace Prefix:	myrg_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

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- Definition

Rental expense incurred for leased assets including furniture and equipment which has not been recognized in costs and expenses applicable to sales and revenues; for example, cost of goods sold or other operating costs and expenses.

+ References

No definition available.

+ Details

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

- Details

Name:	us-gaap_OperatingLeasedAssetsLineItems
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Period Type:	duration

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- Definition

Amount of required minimum rental payments maturing in the next fiscal year following the latest fiscal year for operating leases having an initial or remaining non-cancelable letter-terms in excess of one year.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 13

-Paragraph 16

-Subparagraph b(i)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 13

-Paragraph 122

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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-Publisher FASB

-Name Accounting Standards Codification

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-SubTopic 10

-Section 55

-Paragraph 40

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-SubTopic 20

-Section 50

-Paragraph 2

-Subparagraph (a)

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- Definition

Amount of required minimum rental payments maturing in the fifth fiscal year following the latest fiscal year for operating leases having an initial or remaining non-cancelable letter-terms in excess of one year.

+ References

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- Definition

Amount of required minimum rental payments maturing in the forth fiscal year following the latest fiscal year for operating leases having an initial or remaining non-cancelable letter-terms in excess of one year.

+ References

+ Details

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- Definition

Amount of required minimum rental payments maturing in the third fiscal year following the latest fiscal year for operating leases having an initial or remaining non-cancelable letter-terms in excess of one year.

+ References

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- Definition

Amount of required minimum rental payments maturing in the second fiscal year following the latest fiscal year for operating leases having an initial or remaining non-cancelable letter-terms in excess of one year.

+ References

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- Definition

Amount of required minimum rental payments maturing after the fifth fiscal year following the latest fiscal year for operating leases having an initial or remaining non-cancelable letter-terms in excess of one year.

+ References

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- Definition

The floor amount as of the balance sheet date that the entity must expend to satisfy the terms of disclosed arrangements (excluding long-term commitments) in which the entity has agreed to expend funds to procure goods or services from one or more suppliers, other than under a long-term purchase commitment or an unconditional purchase obligation.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 17

-Article 9

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

-Publisher FASB

-Name Accounting Standards Codification

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-Publisher FASB

-Name Accounting Standards Codification

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-SubTopic 210

-Section S99

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-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

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-Name Regulation S-X (SX)

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-Section 02

-Paragraph 25

-Article 5

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 19

-Article 7

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Commitments and Contingencies (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012 item	Dec. 31, 2011 item	Dec. 31, 2010
Commitments and Contingencies
Number of irrevocable standby letters of credit outstanding	2	2
Number of letters of credit related to the payment obligation under insurance programs	1	1
Letters of credit outstanding related to the payment obligation under insurance programs	$ 17.5	$ 15.0
Letters of credit outstanding related to contract performance obligations	2.2	2.2
Future minimum lease payments for operating leases
2013	2.7
2014	1.1
2015	0.5
2016	0.2
2017	0.2
Thereafter	0.4
Operating lease, additional disclosure
Rent expense	43.1	32.2	31.4
Purchase Commitments for Construction Equipment
Outstanding purchase obligations for certain construction equipment	$ 5.9
Scheduled period of time for cash outlay requirements	6 months
Minimum
Leases
Term of operating lease	1 year
Maximum
Leases
Term of operating lease	9 years