Estimated cost to complete bonded projects.

No definition available.

Name:	myrg_EstimatedCostToCompleteBondedProjects
Namespace Prefix:	myrg_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Represents the amount of the compensatory damages award that was returned against the defendants in the legal matter.

+ References

No definition available.

+ Details

Name:	myrg_LossContingencyCompensatoryDamagesAwardedValue
Namespace Prefix:	myrg_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Represents the amount of deductible under health insurance benefits for qualified individuals.

+ References

No definition available.

+ Details

Name:	myrg_LossContingencyHealthInsuranceDeductibleForQualifiedIndividuals
Namespace Prefix:	myrg_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Represents the insurance expenses, including premiums, for workers' compensation, general liability, automobile liability and employee health benefits.

+ References

No definition available.

+ Details

Name:	myrg_LossContingencyInsuranceExpense
Namespace Prefix:	myrg_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Represents the amount of deductible up to the claim aggregate under insurance arrangements, for each line of coverage excluding auto liability and medical insurance, excluding health insurance.

+ References

No definition available.

+ Details

Name:	myrg_LossContingencyInsurancePolicyDeductibleForEachLineOfCoverageExcludingHealth
Namespace Prefix:	myrg_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Represents the amount of the proposed punitive damage awards issued in a legal judgment.

+ References

No definition available.

+ Details

Name:	myrg_LossContingencyPunitiveDamagesAwardedValue
Namespace Prefix:	myrg_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The total amount of outstanding performance bonds.

+ References

No definition available.

+ Details

Name:	myrg_OutstandingPerformanceBonds
Namespace Prefix:	myrg_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Represents the period during which the defendant operated a manufactured gas plant.

+ References

No definition available.

+ Details

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

- Definition

Represents the amount of reserve established for expense relating to settlement of litigation.

+ References

No definition available.

+ Details

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

- Definition

The value (monetary amount) of the award the plaintiff seeks in the legal matter.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14326-108349

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 50

-Paragraph 4

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14435-108349

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 50

-Paragraph 9

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14557-108349

+ Details

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

- Details

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

- Details

Name:	us-gaap_LitigationCaseAxis=myrg_NorthernStatesPowerCompanyWisconsinVsCityOfAshlandWisconsinMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LitigationCaseAxis=myrg_VehicularTrafficAccidentCaseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LossContingenciesByNatureOfContingencyAxis=us-gaap_InsuranceClaimsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Commitments and Contingencies (Details Textual 2) (USD $) In Millions, unless otherwise specified	12 Months Ended			1 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jan. 31, 2013	Sep. 30, 2013
Other Commitments [Line Items]
Loss Contingency Insurance Policy Deductible for Each Line of Coverage Excluding Health	$ 1.0
Loss Contingency Health Insurance Deductible For Qualified Individuals	0.1
Outstanding Performance Bonds	825.1myrg_OutstandingPerformanceBonds
Estimated Cost to Complete Bonded Projects	125.9
Insurance Claims [Member]
Other Commitments [Line Items]
Loss Contingency Insurance Expense	21.0	20.1	20.9
Vehicular Traffic Accident Case [Member]
Other Commitments [Line Items]
Reserve for Legal Settlements					2.3
Vehicular Traffic Accident Case [Member] \| LE Myers Co [Member]
Other Commitments [Line Items]
Loss Contingency Compensatory Damages Awarded Value	0.7
Loss Contingency Punitive Damages Awarded Value	3.6
Northern States Power Company Wisconsin Vs The City of Ashland Wisconsin [Member] \| LE Myers Co [Member]
Other Commitments [Line Items]
Loss Contingency, Damages Sought, Value				$ 140
Northern States Power Company Wisconsin Vs The City of Ashland Wisconsin [Member] \| LE Myers Co [Member] \| Minimum [Member]
Other Commitments [Line Items]
Period During Which Defendant Operated Manufactured Gas Plant				6 years
Northern States Power Company Wisconsin Vs The City of Ashland Wisconsin [Member] \| LE Myers Co [Member] \| Maximum [Member]
Other Commitments [Line Items]
Period During Which Defendant Operated Manufactured Gas Plant				12 years