Date the credit agreement expires.

No definition available.

Name:	eme_CreditAgreementExpirationDate1
Namespace Prefix:	eme_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Credit Agreement, Initiation Date

+ References

No definition available.

+ Details

Name:	eme_CreditAgreementInitiationDate1
Namespace Prefix:	eme_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of increase in borrowing capacity if additional lenders are identified and/or existing lenders are willing to increase their current commitments.

+ References

No definition available.

+ Details

Name:	eme_IncreaseBorrowingCapacity
Namespace Prefix:	eme_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Letters of credit maximum borrowing capacity.

+ References

No definition available.

+ Details

Name:	eme_LettersOfCreditMaximumBorrowingCapacity
Namespace Prefix:	eme_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Range of letter of credit fees.

+ References

No definition available.

+ Details

Name:	eme_RangeOfLetterOfCreditFees
Namespace Prefix:	eme_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of the total principal payments made during the annual reporting period.

+ References

+ Details

Name:	us-gaap_DebtInstrumentAnnualPrincipalPayment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

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

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, before accumulated amortization, of debt issuance costs. 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 45
-Paragraph 3
-URI https://asc.fasb.org/extlink&oid=124435984&loc=d3e28555-108399

+ Details

Name:	us-gaap_DeferredFinanceCostsGross
Namespace Prefix:	us-gaap_
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

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

- Definition

The effective interest rate at the end of the reporting period.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityInterestRateAtPeriodEnd
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Description of interest rate for borrowing under credit facility. Includes, but is not limited to, terms and method for determining interest rate.

+ References

+ Details

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

- 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_LineOfCreditFacilityLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
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

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
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

Name:	us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, excluding unamortized premium (discount) and debt issuance cost, of long-term debt. Excludes lease obligation.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)(3)
-URI https://asc.fasb.org/extlink&oid=123466204&loc=SL6031897-161870

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 55
-Paragraph 69C
-URI https://asc.fasb.org/extlink&oid=123466577&loc=SL123495737-112612

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16))
-URI https://asc.fasb.org/extlink&oid=126734703&loc=d3e572229-122910

Reference 4: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 55
-Paragraph 69B
-URI https://asc.fasb.org/extlink&oid=123466577&loc=SL123495735-112612

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI https://asc.fasb.org/extlink&oid=126897435&loc=d3e534808-122878

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1D
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=123466505&loc=SL123495340-112611

Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

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

- Definition

The interest rate applicable to the portion of the carrying amount of long-term borrowings outstanding as of the balance sheet date, including current maturities, which accrues interest at a rate subject to change from time to time.

+ References

+ Details

Name:	us-gaap_LongTermDebtPercentageBearingVariableInterestRate
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The carrying value as of the balance sheet date of the noncurrent portion 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
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 10
-Section 45
-Paragraph 14
-URI https://asc.fasb.org/extlink&oid=99376301&loc=d3e1336-112600

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 10
-Section 45
-Paragraph 13
-URI https://asc.fasb.org/extlink&oid=99376301&loc=d3e1314-112600

+ Details

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

- Details

Name:	us-gaap_DebtInstrumentAxis=eme_CreditAgreement2020Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=eme_RevolvingCreditFacility2020Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=eme_TermLoan2020Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_BaseRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=eme_CreditAgreementBaseRateBankofMontrealPrimeRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=eme_CreditAgreementBaseRateDailyOneMonthLIBORRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=eme_CreditAgreementBaseRateFederalFundsRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=eme_CreditAgreement0BaseRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Debt (Narrative) (Details) - USD ($)		9 Months Ended	12 Months Ended
Debt (Narrative) (Details) - USD ($)	Mar. 02, 2020	Sep. 30, 2022	Dec. 31, 2021	Dec. 31, 2022
Line of Credit Facility [Line Items]
Borrowings under revolving credit facility (in US dollars)		$ 170,000,000	$ 0
Letters of credit outstanding (in US dollars)		$ 71,400,000	71,300,000
Interest rate description		At the Company’s election, borrowings under the 2020 Credit Agreement bear interest at either: (1) a base rate plus a margin of 0.00% to 0.75%, based on certain financial tests, or (2) United States dollar LIBOR (3.67% at September 30, 2022) plus 1.00% to 1.75%, based on certain financial tests. The base rate is determined by the greater of: (a) the prime commercial lending rate announced by Bank of Montreal from time to time (6.25% at September 30, 2022), (b) the federal funds effective rate, plus 1/2 of 1.00%, (c) the daily one month LIBOR rate, plus 1.00%, or (d) 0.00%. Upon the discontinuation of LIBOR, our 2020 Credit Agreement contains provisions which allow for the use of alternate benchmark rates. The weighted average interest rates in effect at September 30, 2022 were 4.67% for the 2020 Term Loan and 4.20% for the 2020 Revolving Credit Facility. The interest rate in effect at December 31, 2021 for the 2020 Term Loan was 1.10%. A commitment fee is payable on the average daily unused amount of the 2020 Revolving Credit Facility, which ranges from 0.10% to 0.25%, based on certain financial tests. The fee was 0.10% of the unused amount as of September 30, 2022 and December 31, 2021. Fees for letters of credit issued under the 2020 Revolving Credit Facility range from 0.75% to 1.75% of the respective face amounts of outstanding letters of credit, depending on the nature of the letter of credit, and are computed based on certain financial tests.
2020 Credit Agreement
Line of Credit Facility [Line Items]
Credit agreement, initiation date	Mar. 02, 2020
Expiration date of credit agreement		Mar. 02, 2025
Debt issuance costs	$ 3,100,000
2020 Revolving Credit Facility
Line of Credit Facility [Line Items]
Borrowings under revolving credit facility (in US dollars)		$ 170,000,000	0
Interest rate		4.20%
2020 Term Loan
Line of Credit Facility [Line Items]
Term Loan (in US dollars)	300,000,000	$ 256,688,000	$ 256,688,000
Interest rate		4.67%	1.10%
2020 Term Loan \| Subsequent Event
Line of Credit Facility [Line Items]
Term loan, annual principal payments (in US dollars)				$ 13,900,000
Base Rate [Member] \| Minimum [Member] \| 2020 Credit Agreement
Line of Credit Facility [Line Items]
Basis spread on variable rate		0.00%
Base Rate [Member] \| Maximum [Member] \| 2020 Credit Agreement
Line of Credit Facility [Line Items]
Basis spread on variable rate		0.75%
Prime Rate, Bank of Montreal [Member] \| 2020 Credit Agreement
Line of Credit Facility [Line Items]
Commercial lending rate		6.25%
Credit Agreement Base Rate, Daily One Month LIBOR Rate [Member] \| 2020 Credit Agreement
Line of Credit Facility [Line Items]
Basis spread on variable rate		1.00%
London Interbank Offered Rate (LIBOR) [Member] \| 2020 Credit Agreement
Line of Credit Facility [Line Items]
Commercial lending rate		3.67%
London Interbank Offered Rate (LIBOR) [Member] \| Minimum [Member] \| 2020 Credit Agreement
Line of Credit Facility [Line Items]
Basis spread on variable rate		1.00%
London Interbank Offered Rate (LIBOR) [Member] \| Maximum [Member] \| 2020 Credit Agreement
Line of Credit Facility [Line Items]
Basis spread on variable rate		1.75%
Credit Agreement Base Rate, Federal Funds Rate [Member] \| 2020 Credit Agreement
Line of Credit Facility [Line Items]
Basis spread on variable rate		0.50%
Credit Agreement, 0% Base Rate [Member] \| 2020 Credit Agreement
Line of Credit Facility [Line Items]
Basis spread on variable rate		0.00%
Revolving Credit Facility [Member] \| 2020 Revolving Credit Facility
Line of Credit Facility [Line Items]
Line of credit facility maximum borrowing capacity (in US dollars)	$ 1,300,000,000
Increase in borrowing capacity (in US dollars)		$ 1,900,000,000
Letters of credit maximum borrowing capacity (in US dollars)		$ 400,000,000
Commitment fee percentage of unused amount		0.10%	0.10%
Revolving Credit Facility [Member] \| Minimum [Member] \| 2020 Revolving Credit Facility
Line of Credit Facility [Line Items]
Commitment fee percentage of unused amount		0.10%
Letter of credit fees		0.75%
Revolving Credit Facility [Member] \| Maximum [Member] \| 2020 Revolving Credit Facility
Line of Credit Facility [Line Items]
Commitment fee percentage of unused amount		0.25%
Letter of credit fees		1.75%