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EMPLOYEE BENEFITS - Schedule of Prepaid Assets (Details) - USD ($) $ in Millions | Dec. 31, 2022 | Dec. 31, 2021
--- | --- | ---
Defined Benefit Plan Disclosure [Line Items] |  |
Prepaid asset | $ 1,045.5 | $ 272.0
Less: Accrued SERP - current portion | (47.3) | (9.7)
Accrued Pension, SERP and PBOP | 135.5 | 242.5
CL&P |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Prepaid asset | 147.9 | 0.4
Less: Accrued SERP - current portion | (0.3) | (0.5)
Accrued Pension, SERP and PBOP | 12.9 | 26.8
NSTAR Electric |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Prepaid asset | 576.8 | 441.4
Less: Accrued SERP - current portion | (0.2) | (0.2)
Accrued Pension, SERP and PBOP | 1.6 | 2.0
PSNH |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Prepaid asset | 66.4 | 0.0
Less: Accrued SERP - current portion | (0.4) | (0.5)
Accrued Pension, SERP and PBOP | 6.5 | 30.2
Pension Plan |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Prepaid asset | 756.7 | 0.0
Accrued liability, defined benefit pension plan | 3.7 | 58.1
Pension Plan | CL&P |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Prepaid asset | 147.9 | 0.4
Accrued liability, defined benefit pension plan | 0.0 | 0.0
Pension Plan | NSTAR Electric |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Prepaid asset | 310.2 | 149.8
Accrued liability, defined benefit pension plan | 0.0 | 0.0
Pension Plan | PSNH |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Prepaid asset | 66.4 | 0.0
Accrued liability, defined benefit pension plan | 0.0 | 20.6
PBOP |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Prepaid asset | 288.8 | 272.0
Accrued liability, defined benefit pension plan | 12.4 | 18.0
PBOP | CL&P |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Prepaid asset | 0.0 | 0.0
Accrued liability, defined benefit pension plan | 7.3 | 19.8
PBOP | NSTAR Electric |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Prepaid asset | 266.6 | 291.6
Accrued liability, defined benefit pension plan | 0.0 | 0.0
PBOP | PSNH |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Prepaid asset | 0.0 | 0.0
Accrued liability, defined benefit pension plan | 2.3 | 4.3
SERP |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Accrued liability, defined benefit pension plan | 166.7 | 176.1
SERP | CL&P |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Accrued liability, defined benefit pension plan | 5.9 | 7.5
SERP | NSTAR Electric |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Accrued liability, defined benefit pension plan | 1.8 | 2.2
SERP | PSNH |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Accrued liability, defined benefit pension plan | $ 4.6 | $ 5.8

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