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EMPLOYEE BENEFITS - Schedule of Prepaid Assets (Details) - USD ($) $ in Millions | Dec. 31, 2023 | Dec. 31, 2022
--- | --- | ---
Defined Benefit Plan Disclosure [Line Items] |  |
Prepaid asset | $ 1,028.2 | $ 1,045.5
Less: Accrued SERP - current portion | (19.4) | (47.3)
Accrued Pension, SERP and PBOP | 123.8 | 135.5
CL&P |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Prepaid asset | 129.8 | 147.9
Less: Accrued SERP - current portion | (0.3) | (0.3)
Accrued Pension, SERP and PBOP | 5.6 | 12.9
NSTAR Electric |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Prepaid asset | 608.6 | 576.8
Less: Accrued SERP - current portion | (0.2) | (0.2)
Accrued Pension, SERP and PBOP | 1.7 | 1.6
PSNH |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Prepaid asset | 59.0 | 66.4
Less: Accrued SERP - current portion | (0.4) | (0.4)
Accrued Pension, SERP and PBOP | 4.2 | 6.5
Pension Plan |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Prepaid asset | 672.2 | 756.7
Accrued liability, defined benefit pension plan | 0.0 | 3.7
Pension Plan | CL&P |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Prepaid asset | 127.4 | 147.9
Accrued liability, defined benefit pension plan | 0.0 | 0.0
Pension Plan | NSTAR Electric |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Prepaid asset | 306.5 | 310.2
Accrued liability, defined benefit pension plan | 0.0 | 0.0
Pension Plan | PSNH |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Prepaid asset | 56.3 | 66.4
Accrued liability, defined benefit pension plan | 0.0 | 0.0
PBOP |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Prepaid asset | 356.0 | 288.8
Accrued liability, defined benefit pension plan | 7.6 | 12.4
PBOP | CL&P |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Prepaid asset | 2.4 | 0.0
Accrued liability, defined benefit pension plan | 0.0 | 7.3
PBOP | NSTAR Electric |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Prepaid asset | 302.1 | 266.6
Accrued liability, defined benefit pension plan | 0.0 | 0.0
PBOP | PSNH |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Prepaid asset | 2.7 | 0.0
Accrued liability, defined benefit pension plan | 0.0 | 2.3
SERP |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Accrued liability, defined benefit pension plan | 135.6 | 166.7
SERP | CL&P |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Accrued liability, defined benefit pension plan | 5.9 | 5.9
SERP | NSTAR Electric |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Accrued liability, defined benefit pension plan | 1.9 | 1.8
SERP | PSNH |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Accrued liability, defined benefit pension plan | $ 4.6 | $ 4.6

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