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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1B
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611

Reference 2: 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(a)(1))
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	dtr-types: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_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The cash inflow during the period from additional borrowings in aggregate debt. Includes proceeds from short-term and long-term debt.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=126954810&loc=d3e3255-108585

+ Details

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

- Definition

The cash outflow for debt initially having maturity due after one year or beyond the normal operating cycle, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=126954810&loc=d3e3291-108585

+ Details

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

- Details

Name:	dei_LegalEntityAxis=es_TheConnecticutLightAndPowerCompanyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_DebtInstrumentAxis=es_CLP2023525SeriesAFirstMortgageBondsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=es_CLP2013250SeriesAFirstMortgageBondsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=es_PublicServiceCompanyOfNewHampshirePSNHMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=es_PSNH515SeriesWFirstMortgageBondsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ConsolidatedEntitiesAxis=srt_ParentCompanyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_DebtInstrumentAxis=es_EversourceParent545SeriesZSeniorNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=es_EversourceParent280SeriesFSeniorNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementScenarioAxis=srt_ScenarioForecastMember
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:

SHORT-TERM AND LONG-TERM DEBT - Summary of Long-Term Debt Issuance and Repayments (Details) - USD ($) $ in Thousands	1 Months Ended			3 Months Ended
	May 31, 2023	Mar. 31, 2023	Jan. 31, 2023	Mar. 31, 2023	Mar. 31, 2022
Debt Instrument [Line Items]
Retirement of Long-Term Debt				$ (400,000)	$ (770,000)
CL&P
Debt Instrument [Line Items]
Retirement of Long-Term Debt				$ (400,000)	$ 0
CL&P \| First Mortgage \| CL&P 2023 Series A First Mortgage Bonds
Debt Instrument [Line Items]
Interest rate, stated percentage			5.25%
Issuances			$ 500,000
CL&P \| First Mortgage \| CL&P 2013 Series A First Mortgage Bonds
Debt Instrument [Line Items]
Interest rate, stated percentage			2.50%
Retirement of Long-Term Debt			$ (400,000)
PSNH \| First Mortgage \| PSNH Series W First Mortgage Bonds
Debt Instrument [Line Items]
Interest rate, stated percentage			5.15%
Issuances			$ 300,000
Eversource Parent \| Senior Notes \| Eversource Parent Series Z Senior Notes
Debt Instrument [Line Items]
Interest rate, stated percentage		5.45%		5.45%
Issuances		$ 750,000
Eversource Parent \| Senior Notes \| Eversource Parent Series F Senior Notes \| Forecast
Debt Instrument [Line Items]
Interest rate, stated percentage	2.80%
Eversource Parent \| Senior Notes \| Eversource Parent Series F Senior Notes \| Subsequent Event \| Forecast
Debt Instrument [Line Items]
Retirement of Long-Term Debt	$ (450,000)