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EMPLOYEE BENEFITS - Schedule of Prepaid Assets (Details) - USD ($) $ in Millions | Dec. 31, 2024 | Dec. 31, 2023
--- | --- | ---
Defined Benefit Plan Disclosure [Line Items] |  |
Prepaid asset | $ 1,336.6 | $ 1,028.2
Less: Accrued SERP - current portion | (24.0) | (19.4)
Accrued SERP and PBOP | 95.4 | 123.8
CL&P |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Prepaid asset | 182.5 | 129.8
Less: Accrued SERP - current portion | (0.4) | (0.3)
Accrued SERP and PBOP | 5.3 | 5.6
NSTAR Electric |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Prepaid asset | 724.7 | 608.6
Less: Accrued SERP - current portion | (0.2) | (0.2)
Accrued SERP and PBOP | 2.0 | 1.7
PSNH |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Prepaid asset | 91.0 | 59.0
Less: Accrued SERP - current portion | (0.4) | (0.4)
Accrued SERP and PBOP | 4.1 | 4.2
Pension Plan |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Prepaid asset | 887.7 | 672.2
Pension Plan | CL&P |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Prepaid asset | 167.2 | 127.4
Pension Plan | NSTAR Electric |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Prepaid asset | 376.9 | 306.5
Pension Plan | PSNH |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Prepaid asset | 80.5 | 56.3
PBOP |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Prepaid asset | 448.9 | 356.0
Accrued liability, defined benefit pension plan | 0.0 | 7.6
PBOP | CL&P |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Prepaid asset | 15.3 | 2.4
Accrued liability, defined benefit pension plan | 0.0 | 0.0
PBOP | NSTAR Electric |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Prepaid asset | 347.8 | 302.1
Accrued liability, defined benefit pension plan | 0.0 | 0.0
PBOP | PSNH |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Prepaid asset | 10.5 | 2.7
Accrued liability, defined benefit pension plan | 0.0 | 0.0
SERP |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Accrued liability, defined benefit pension plan | 119.4 | 135.6
SERP | CL&P |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Accrued liability, defined benefit pension plan | 5.7 | 5.9
SERP | NSTAR Electric |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Accrued liability, defined benefit pension plan | 2.2 | 1.9
SERP | PSNH |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Accrued liability, defined benefit pension plan | $ 4.5 | $ 4.6

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