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EMPLOYEE BENEFITS - Schedule of Pension Benefit Obligations (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022
Pension and SERP |  |  |
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward] |  |  |
Benefit Obligation as of Beginning of Year | $ (5,238.4) | $ (5,220.1) |
Service Cost | (44.3) | (43.1) | $ (70.1)
Interest Cost | (250.0) | (254.0) | (154.5)
Actuarial Gain/(Loss) | 280.2 | (110.4) |
Benefits Paid | 320.9 | 317.3 |
Benefits Paid - Lump Sum | 24.0 | 28.9 |
Benefits Paid - SERP | 19.4 | 43.0 |
Employee Transfers | 0.0 | 0.0 |
Reclassified to Assets Held for Sale | 142.5 | 0.0 |
Benefit Obligation as of End of Year | (4,745.7) | (5,238.4) | (5,220.1)
Change in Pension Plan Assets: |  |  |
Fair Value of Plan Assets as of Beginning of Year | 5,775.0 | 5,806.4 |
Employer Contributions | 5.0 | 5.0 |
Actual Return on Plan Assets | 227.0 | 309.8 |
Benefits Paid - Pension | (320.9) | (317.3) |
Benefits Paid - Lump Sum | (24.0) | (28.9) |
Employee Transfers | 0.0 | 0.0 |
Reclassified to Assets Held for Sale | 148.1 | 0.0 |
Fair Value of Plan Assets as of End of Year | 5,514.0 | 5,775.0 | 5,806.4
Funded Status as of December 31st | 768.3 | 536.6 |
PBOP |  |  |
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward] |  |  |
Benefit Obligation as of Beginning of Year | (676.0) | (693.7) |
Service Cost | (7.0) | (7.6) | (11.6)
Interest Cost | (31.9) | (33.8) | (20.2)
Actuarial Gain/(Loss) | 41.3 | 5.0 |
Benefits Paid | 51.7 | 52.7 |
Employee Transfers | 0.0 | 0.0 |
Reclassified to Assets Held for Sale | 34.5 | 0.0 |
Plan Amendment | 0.0 | 1.4 |
Benefit Obligation as of End of Year | (587.4) | (676.0) | (693.7)
Change in Pension Plan Assets: |  |  |
Fair Value of Plan Assets as of Beginning of Year | 1,024.4 | 970.1 |
Employer Contributions | 0.9 | 1.9 |
Actual Return on Plan Assets | 92.3 | 104.7 |
Benefits Paid - Pension | (51.8) | (52.3) |
Employee Transfers | 0.0 | 0.0 |
Reclassified to Assets Held for Sale | 29.5 | 0.0 |
Fair Value of Plan Assets as of End of Year | 1,036.3 | 1,024.4 | 970.1
Funded Status as of December 31st | 448.9 | 348.4 |
CL&P | Pension and SERP |  |  |
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward] |  |  |
Benefit Obligation as of Beginning of Year | (1,048.5) | (1,030.0) |
Service Cost | (12.7) | (12.3) | (18.7)
Interest Cost | (50.3) | (50.5) | (31.3)
Actuarial Gain/(Loss) | 56.2 | (19.7) |
Benefits Paid | 68.1 | 66.1 |
Benefits Paid - Lump Sum | 0.0 | 0.0 |
Benefits Paid - SERP | 0.3 | 0.3 |
Employee Transfers | 4.0 | (2.4) |
Reclassified to Assets Held for Sale | 0.0 | 0.0 |
Benefit Obligation as of End of Year | (982.9) | (1,048.5) | (1,030.0)
Change in Pension Plan Assets: |  |  |
Fair Value of Plan Assets as of Beginning of Year | 1,170.0 | 1,172.0 |
Employer Contributions | 0.0 | 0.0 |
Actual Return on Plan Assets | 46.5 | 61.7 |
Benefits Paid - Pension | (68.1) | (66.1) |
Benefits Paid - Lump Sum | 0.0 | 0.0 |
Employee Transfers | (4.0) | 2.4 |
Reclassified to Assets Held for Sale | 0.0 | 0.0 |
Fair Value of Plan Assets as of End of Year | 1,144.4 | 1,170.0 | 1,172.0
Funded Status as of December 31st | 161.5 | 121.5 |
CL&P | PBOP |  |  |
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward] |  |  |
Benefit Obligation as of Beginning of Year | (120.6) | (127.9) |
Service Cost | (1.2) | (1.3) | (2.0)
Interest Cost | (5.6) | (6.2) | (3.7)
Actuarial Gain/(Loss) | 8.9 | 4.4 |
Benefits Paid | 9.4 | 10.0 |
Employee Transfers | 0.0 | 0.0 |
Reclassified to Assets Held for Sale | 0.0 | 0.0 |
Plan Amendment | 0.0 | 0.4 |
Benefit Obligation as of End of Year | (109.1) | (120.6) | (127.9)
Change in Pension Plan Assets: |  |  |
Fair Value of Plan Assets as of Beginning of Year | 123.0 | 120.6 |
Employer Contributions | 0.0 | 0.0 |
Actual Return on Plan Assets | 11.2 | 12.6 |
Benefits Paid - Pension | (9.4) | (10.0) |
Employee Transfers | (0.4) | (0.2) |
Reclassified to Assets Held for Sale | 0.0 | 0.0 |
Fair Value of Plan Assets as of End of Year | 124.4 | 123.0 | 120.6
Funded Status as of December 31st | 15.3 | 2.4 |
NSTAR Electric | Pension and SERP |  |  |
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward] |  |  |
Benefit Obligation as of Beginning of Year | (1,107.0) | (1,110.4) |
Service Cost | (7.7) | (7.8) | (13.8)
Interest Cost | (51.6) | (53.9) | (32.8)
Actuarial Gain/(Loss) | 74.1 | (17.6) |
Benefits Paid | 67.1 | 76.7 |
Benefits Paid - Lump Sum | 7.6 | 5.3 |
Benefits Paid - SERP | 0.2 | 0.2 |
Employee Transfers | 13.8 | 0.5 |
Reclassified to Assets Held for Sale | 0.0 | 0.0 |
Benefit Obligation as of End of Year | (1,003.5) | (1,107.0) | (1,110.4)
Change in Pension Plan Assets: |  |  |
Fair Value of Plan Assets as of Beginning of Year | 1,411.6 | 1,418.8 |
Employer Contributions | 0.0 | 0.0 |
Actual Return on Plan Assets | 55.1 | 75.3 |
Benefits Paid - Pension | (67.1) | (76.7) |
Benefits Paid - Lump Sum | (7.6) | (5.3) |
Employee Transfers | (13.8) | (0.5) |
Reclassified to Assets Held for Sale | 0.0 | 0.0 |
Fair Value of Plan Assets as of End of Year | 1,378.2 | 1,411.6 | 1,418.8
Funded Status as of December 31st | 374.7 | 304.6 |
NSTAR Electric | PBOP |  |  |
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward] |  |  |
Benefit Obligation as of Beginning of Year | (188.3) | (189.5) |
Service Cost | (1.2) | (1.2) | (2.0)
Interest Cost | (8.8) | (9.2) | (5.3)
Actuarial Gain/(Loss) | 10.7 | (5.8) |
Benefits Paid | 15.9 | 16.7 |
Employee Transfers | 0.3 | 0.5 |
Reclassified to Assets Held for Sale | 0.0 | 0.0 |
Plan Amendment | 0.0 | 0.2 |
Benefit Obligation as of End of Year | (171.4) | (188.3) | (189.5)
Change in Pension Plan Assets: |  |  |
Fair Value of Plan Assets as of Beginning of Year | 490.4 | 456.1 |
Employer Contributions | 0.0 | 0.0 |
Actual Return on Plan Assets | 45.8 | 52.3 |
Benefits Paid - Pension | (15.9) | (16.7) |
Employee Transfers | (1.1) | (1.3) |
Reclassified to Assets Held for Sale | 0.0 | 0.0 |
Fair Value of Plan Assets as of End of Year | 519.2 | 490.4 | 456.1
Funded Status as of December 31st | 347.8 | 302.1 |
PSNH | Pension and SERP |  |  |
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward] |  |  |
Benefit Obligation as of Beginning of Year | (562.3) | (556.2) |
Service Cost | (4.3) | (4.3) | (6.9)
Interest Cost | (26.8) | (27.3) | (16.9)
Actuarial Gain/(Loss) | 30.7 | (11.6) |
Benefits Paid | 38.0 | 35.7 |
Benefits Paid - Lump Sum | 0.1 | 1.0 |
Benefits Paid - SERP | 0.4 | 0.4 |
Employee Transfers | 2.7 | 0.0 |
Reclassified to Assets Held for Sale | 0.0 | 0.0 |
Benefit Obligation as of End of Year | (521.5) | (562.3) | (556.2)
Change in Pension Plan Assets: |  |  |
Fair Value of Plan Assets as of Beginning of Year | 614.0 | 618.0 |
Employer Contributions | 0.0 | 0.0 |
Actual Return on Plan Assets | 24.3 | 32.7 |
Benefits Paid - Pension | (38.0) | (35.7) |
Benefits Paid - Lump Sum | (0.1) | (1.0) |
Employee Transfers | (2.7) | 0.0 |
Reclassified to Assets Held for Sale | 0.0 | 0.0 |
Fair Value of Plan Assets as of End of Year | 597.5 | 614.0 | 618.0
Funded Status as of December 31st | 76.0 | 51.7 |
PSNH | PBOP |  |  |
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward] |  |  |
Benefit Obligation as of Beginning of Year | (72.0) | (74.6) |
Service Cost | (0.6) | (0.7) | (1.1)
Interest Cost | (3.4) | (3.7) | (2.2)
Actuarial Gain/(Loss) | 3.9 | 0.8 |
Benefits Paid | 6.2 | 6.1 |
Employee Transfers | 0.0 | (0.1) |
Reclassified to Assets Held for Sale | 0.0 | 0.0 |
Plan Amendment | 0.0 | 0.2 |
Benefit Obligation as of End of Year | (65.9) | (72.0) | (74.6)
Change in Pension Plan Assets: |  |  |
Fair Value of Plan Assets as of Beginning of Year | 74.7 | 72.3 |
Employer Contributions | 0.0 | 0.0 |
Actual Return on Plan Assets | 7.6 | 8.3 |
Benefits Paid - Pension | (6.1) | (6.1) |
Employee Transfers | 0.2 | 0.2 |
Reclassified to Assets Held for Sale | 0.0 | 0.0 |
Fair Value of Plan Assets as of End of Year | 76.4 | 74.7 | $ 72.3
Funded Status as of December 31st | $ 10.5 | $ 2.7 |

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