v3.25.4

Retirement Benefits (Schedule of Net Benefit Costs) (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2025 | Dec. 31, 2024 | Dec. 31, 2023
DB Pension Plans and DB SERP |  |  |
Defined Benefit Plan, Roll Forwards [Abstract] |  |  |
Service cost | $ 25 | $ 28 | $ 29
Interest cost | 114 | 109 | 112
Expected return on plan assets | (229) | (234) | (220)
Amortization of: |  |  |
Net loss | 11 | 12 | 12
Prior service cost (credit) | 4 | 4 | 4
Settlement loss | 11 | 11 | 11
Net periodic credit | (64) | (70) | (52)
DB Pension Plans and DB SERP | Consumers Energy Company |  |  |
Defined Benefit Plan, Roll Forwards [Abstract] |  |  |
Service cost | 24 | 27 | 28
Interest cost | 106 | 102 | 105
Expected return on plan assets | (215) | (221) | (208)
Amortization of: |  |  |
Net loss | 10 | 11 | 11
Prior service cost (credit) | 4 | 4 | 4
Settlement loss | 11 | 11 | 11
Net periodic credit | (60) | (66) | (49)
OPEB Plan |  |  |
Defined Benefit Plan, Roll Forwards [Abstract] |  |  |
Service cost | 8 | 11 | 12
Interest cost | 43 | 43 | 44
Expected return on plan assets | (111) | (115) | (103)
Amortization of: |  |  |
Net loss | 3 | 4 | 12
Prior service cost (credit) | (34) | (31) | (41)
Settlement loss | 0 | 0 | 0
Net periodic credit | (91) | (88) | (76)
OPEB Plan | Consumers Energy Company |  |  |
Defined Benefit Plan, Roll Forwards [Abstract] |  |  |
Service cost | 8 | 11 | 11
Interest cost | 42 | 41 | 42
Expected return on plan assets | (104) | (107) | (95)
Amortization of: |  |  |
Net loss | 3 | 4 | 12
Prior service cost (credit) | (33) | (30) | (40)
Settlement loss | 0 | 0 | 0
Net periodic credit | $ (84) | $ (81) | $ (70)

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