Contingencies and Commitments (Summary of Guarantees) (Details) $ in Millions	12 Months Ended
	Dec. 31, 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	$ 304
Carrying Amount	$ 0
Indemnity obligations from stock and asset sale agreements
Guarantees And Other Contingencies [Line Items]
Expiration Date	indefinite
Maximum Obligation	$ 153
Carrying Amount	$ 1