Revenue (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Disaggregation of Revenue [Line Items]
Bad debt expense	$ 33	$ 34	$ 50
Unbilled receivables	584	494
Consumers Energy Company
Disaggregation of Revenue [Line Items]
Bad debt expense	33	34	50
Regulatory liability	4,178	3,950
Unbilled receivables	$ 584	$ 494
Consumers Energy Company | Contributions to assistance programs
Disaggregation of Revenue [Line Items]
Regulatory liability			10
Consumers Energy Company | Voluntary refund mechanism
Disaggregation of Revenue [Line Items]
Regulatory liability			22
Consumers Energy Company | Revenue subject to refund
Disaggregation of Revenue [Line Items]
Regulatory liability			$ 15