Represent the minimum interest coverage ratio under the credit agreement.

No definition available.

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- Definition

Threshold of debt coverage ration at which the credit agreement restricts certain types of payments.

+ References

No definition available.

+ Details

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Data Type:	xbrli:pureItemType
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Period Type:	duration

- Definition

The number of debt instruments.

+ References

No definition available.

+ Details

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Namespace Prefix:	myrg_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of company's consolidated liquidity restricted.

+ References

No definition available.

+ Details

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

- Definition

The Company has the option to expand the debt coverage ratio in the event of an acquisition.

+ References

No definition available.

+ Details

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- Definition

Represents the option to increase maximum borrowings on the credit facility.

+ References

No definition available.

+ Details

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

- Definition

Percentage of capital stock from direct foreign subsidiaries pledged as collateral for a debt.

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

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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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Data Type:	xbrli:stringItemType
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- Definition

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, after accumulated amortization, of debt issuance costs related to line of credit arrangements. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section S45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=68176171&loc=SL68176184-208336

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- 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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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-SubTopic 10
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-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The fee, expressed as a percentage of the line of credit facility, for the line of credit facility regardless of whether the facility has been used.

+ References

No definition available.

+ Details

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Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
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Debt - Additional information (Details)		9 Months Ended
Debt - Additional information (Details)	Sep. 13, 2019 USD ($)	Sep. 30, 2021 USD ($) equipment_note	Dec. 31, 2020 USD ($)
Revolving loans
Debt Instrument [Line Items]
Debt instrument term		5 years
Secured Debt \| Credit Agreement
Debt Instrument [Line Items]
Debt instrument term	5 years
Maximum borrowing capacity	$ 375,000,000
Option to increase borrowing capacity	$ 200,000,000
Percentage of capital stock from direct foreign subsidiaries	65.00%
Debt instrument covenant leveraged debt ratio restriction	2.50
Debt instrument restricted maximum liquidity	$ 50,000,000
Leverage coverage ratio	3.0
Interest coverage ratio	3.0
Deferred debt issuance costs		$ 900,000
Secured Debt \| Credit Agreement \| Minimum
Debt Instrument [Line Items]
Commitment fee on unused capacity	0.15%
Secured Debt \| Credit Agreement \| Maximum
Debt Instrument [Line Items]
Commitment fee on unused capacity	0.25%
Secured Debt \| Credit Agreement \| Base Rate \| Minimum
Debt Instrument [Line Items]
Interest rate margin	0.00%
Secured Debt \| Credit Agreement \| Base Rate \| Maximum
Debt Instrument [Line Items]
Interest rate margin	0.75%
Secured Debt \| Credit Agreement \| London Interbank Offered Rate (LIBOR) \| Minimum
Debt Instrument [Line Items]
Interest rate margin	1.00%
Secured Debt \| Credit Agreement \| London Interbank Offered Rate (LIBOR) \| Maximum
Debt Instrument [Line Items]
Interest rate margin	1.75%
Secured Debt \| Credit Agreement \| Letter of credit
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 150,000,000
Letters of credit outstanding		12,300,000	$ 10,400,000
Secured Debt \| Credit Agreement \| Letter of credit \| Insurance program obligations
Debt Instrument [Line Items]
Letters of credit outstanding		12,300,000	9,800,000
Secured Debt \| Credit Agreement \| Letter of credit \| Contract performance obligations
Debt Instrument [Line Items]
Letters of credit outstanding			600,000
Secured Debt \| Credit Agreement \| Revolving loans and letters of credit
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 75,000,000
Secured Debt \| Credit Agreement \| Non-performance letters of credit \| Minimum
Debt Instrument [Line Items]
Letter of credit facility commitment percentage	1.00%
Secured Debt \| Credit Agreement \| Non-performance letters of credit \| Maximum
Debt Instrument [Line Items]
Letter of credit facility commitment percentage	1.75%
Secured Debt \| Credit Agreement \| Performance letters of credit \| Minimum
Debt Instrument [Line Items]
Letter of credit facility commitment percentage	0.50%
Secured Debt \| Credit Agreement \| Performance letters of credit \| Maximum
Debt Instrument [Line Items]
Letter of credit facility commitment percentage	0.875%
Secured Debt \| Credit Agreement \| Revolving loans
Debt Instrument [Line Items]
Debt outstanding under facility		$ 0	$ 0
Notes payable to banks \| Master Loan Agreement
Debt Instrument [Line Items]
Number of equipment notes (equipment note) \| equipment_note		1