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v3.24.3

Retirement Benefits (Schedule of Net Benefit Costs) (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2024 | Sep. 30, 2023 | Sep. 30, 2024 | Sep. 30, 2023
DB Pension Plans |  |  |  |
Defined Benefit Plan, Roll Forwards [Abstract] |  |  |  |
Service cost | $ 7 | $ 7 | $ 21 | $ 22
Interest cost | 26 | 27 | 78 | 80
Expected return on plan assets | (58) | (55) | (176) | (165)
Amortization of: |  |  |  |
Net loss | 3 | 2 | 9 | 8
Prior service cost (credit) | 1 | 1 | 3 | 3
Settlement loss | 3 | 3 | 8 | 8
Net periodic credit | (18) | (15) | (57) | (44)
DB Pension Plans | Volatility Mechanism |  |  |  |
Amortization of: |  |  |  |
Deferred credits |  |  | 12 |
DB Pension Plans | Consumers Energy Company |  |  |  |
Defined Benefit Plan, Roll Forwards [Abstract] |  |  |  |
Service cost | 7 | 7 | 20 | 21
Interest cost | 25 | 24 | 74 | 75
Expected return on plan assets | (56) | (52) | (166) | (156)
Amortization of: |  |  |  |
Net loss | 3 | 3 | 8 | 8
Prior service cost (credit) | 1 | 1 | 3 | 3
Settlement loss | 3 | 3 | 8 | 8
Net periodic credit | (17) | (14) | (53) | (41)
OPEB Plan |  |  |  |
Defined Benefit Plan, Roll Forwards [Abstract] |  |  |  |
Service cost | 2 | 2 | 8 | 8
Interest cost | 10 | 11 | 32 | 33
Expected return on plan assets | (28) | (26) | (86) | (77)
Amortization of: |  |  |  |
Net loss | 1 | 3 | 3 | 9
Prior service cost (credit) | (7) | (10) | (23) | (31)
Settlement loss | 0 | 0 | 0 | 0
Net periodic credit | (22) | (20) | (66) | (58)
OPEB Plan | Volatility Mechanism |  |  |  |
Amortization of: |  |  |  |
Deferred credits |  |  | 8 |
OPEB Plan | Consumers Energy Company |  |  |  |
Defined Benefit Plan, Roll Forwards [Abstract] |  |  |  |
Service cost | 2 | 2 | 8 | 8
Interest cost | 11 | 10 | 31 | 31
Expected return on plan assets | (26) | (23) | (80) | (71)
Amortization of: |  |  |  |
Net loss | 1 | 3 | 3 | 9
Prior service cost (credit) | (8) | (10) | (23) | (30)
Settlement loss | 0 | 0 | 0 | 0
Net periodic credit | $ (20) | $ (18) | $ (61) | $ (53)

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