Contingencies and Commitments (Schedule of Guarantees) (Details) $ in Millions |
Sep. 30, 2026
USD ($)
|
|---|---|
| Guarantees | |
| Guarantees And Other Contingencies [Line Items] | |
| Maximum Obligation | $ 30 |
| Carrying Amount | 0 |
| Guarantees | Consumers Energy Company | |
| Guarantees And Other Contingencies [Line Items] | |
| Maximum Obligation | 30 |
| Carrying Amount | 0 |
| Indemnity obligations from sale of membership interests in VIEs | |
| Guarantees And Other Contingencies [Line Items] | |
| Maximum Obligation | 152 |
| Carrying Amount | 0 |
| Indemnity obligations from stock and asset sale agreements | |
| Guarantees And Other Contingencies [Line Items] | |
| Maximum Obligation | 52 |
| Carrying Amount | $ 0 |