Contingencies and Commitments (Summary of Guarantees) (Details) $ in Millions	6 Months Ended
	Jun. 30, 2023 USD ($)
Variable Interest Entity, Primary Beneficiary | Aviator Wind Class B Membership
Guarantees And Other Contingencies [Line Items]
Ownership percentage	49.00%
Guarantees
Guarantees And Other Contingencies [Line Items]
Expiration Date	indefinite
Maximum Obligation	$ 30
Carrying Amount	$ 0
Guarantees | Consumers Energy Company
Guarantees And Other Contingencies [Line Items]
Expiration Date	indefinite
Maximum Obligation	$ 30
Carrying Amount	$ 0
Indemnification agreement from sale of membership interests in VIEs
Guarantees And Other Contingencies [Line Items]
Expiration Date	indefinite
Maximum Obligation	$ 308
Carrying Amount	$ 0
Indemnity obligations from stock and asset sale agreements
Guarantees And Other Contingencies [Line Items]
Expiration Date	indefinite
Maximum Obligation	$ 154
Carrying Amount	$ 2