XML 126 R98.htm IDEA: XBRL DOCUMENT
v3.25.0.1

DERIVATIVE INSTRUMENTS - Narrative (Details) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2024 USD ($) MW | Dec. 31, 2023 USD ($) MW | Dec. 31, 2022 USD ($)
Derivative Instruments and Hedging Activities Disclosures [Line Items] |  |  |
Percentage of costs or benefits borne under capacity-related contracts by United Illuminated Company (as a percentage) | 20.00% |  |
Amount of power to be purchased under capacity-related contract (up to) (in MW) | MW | 610 | 682 |
Gain (loss) on deferred regulatory costs | $ | $ (3.8) | $ (3.9) | $ 10.1
CL&P |  |  |
Derivative Instruments and Hedging Activities Disclosures [Line Items] |  |  |
Percentage of costs or benefits borne under capacity-related contracts (as a percentage) | 80.00% |  |

X
- Definition Amount of Capacity Provided Under Capacity Contract + References No definition available. + Details
Name: | es_AmountofCapacityProvidedUnderCapacityContract
Namespace Prefix: | es_
Data Type: | dtr-types1:powerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Derivative Instruments Gain (Loss) Recognized In Regulatory Asset Liability + References No definition available. + Details
Name: | es_DerivativeInstrumentsGainLossRecognizedInRegulatoryAssetLiability
Namespace Prefix: | es_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Percentage of Costs or Benefits Borne Under Capacity-Related Contracts + References No definition available. + Details
Name: | es_PercentageofCostsorBenefitsBorneUnderCapacityRelatedContracts
Namespace Prefix: | es_
Data Type: | dtr-types1:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of Costs or Benefits Borne Under Capacity-Related Contracts by United Illuminated Company + References No definition available. + Details
Name: | es_PercentageofCostsorBenefitsBorneUnderCapacityRelatedContractsbyUnitedIlluminatedCompany
Namespace Prefix: | es_
Data Type: | dtr-types1:percentItemType
Balance Type: | na
Period Type: | duration

X
- 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_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | dei_LegalEntityAxis=es_TheConnecticutLightAndPowerCompanyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |