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EMPLOYEE BENEFITS - Schedule of Funded Status (Details) - Pension and SERP - USD ($) $ in Millions | Dec. 31, 2024 | Dec. 31, 2023
--- | --- | ---
Defined Benefit Plan Disclosure [Line Items] |  |
Accumulated benefit obligation | $ 4,617.1 | $ 4,936.8
CL&P |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Accumulated benefit obligation | 953.9 | 977.8
NSTAR Electric |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Accumulated benefit obligation | 969.5 | 1,051.9
PSNH |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Accumulated benefit obligation | $ 507.4 | $ 522.1

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- Definition Amount of actuarial present value of benefits attributed to employee service rendered, excluding assumptions about future compensation level. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (e) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-1 + Details
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