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Contingencies and Commitments (Schedule of Remediation and Other Response Activity Costs by Year) (Details) $ in Millions | Sep. 30, 2025 USD ($)
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Consumers Energy Company | MGP sites |
Site Contingency [Line Items] |
2025 | $ 0
2026 | 3
2027 | 8
2028 | 25
2029 | 11
2030 | 3
Bay Harbor |
Site Contingency [Line Items] |
2025 | 1
2026 | 4
2027 | 4
2028 | 4
2029 | 4
2030 | $ 4

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