v3.25.4

Retirement Benefits (Schedule of SERP Trust Assets, ABO and Contributions) (Details) - DB SERP - USD ($) $ in Millions | Dec. 31, 2025 | Dec. 31, 2024
--- | --- | ---
Defined Benefit Plan Disclosure [Line Items] |  |
ABO | $ 104 | $ 105
Consumers Energy Company |  |
Defined Benefit Plan Disclosure [Line Items] |  |
ABO | 76 | 76
Trust assets |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Trust assets | 122 | 127
Trust assets | Consumers Energy Company |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Trust assets | $ 92 | $ 95

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