Revenue (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Disaggregation of Revenue [Line Items]
Bad debt expense	$ 50	$ 22	$ 30
Unbilled receivables	663	486
Regulatory liabilities	104	146
Consumers revenues to be refunded	37		28
Consumers Energy Company
Disaggregation of Revenue [Line Items]
Bad debt expense	50	22	33
Unbilled receivables	663	486
Regulatory liabilities	104	146
Consumers revenues to be refunded	37		28
Consumers Energy Company | Reserve for customer refunds
Disaggregation of Revenue [Line Items]
Commitment to fund contributions to assist low-income customers	10
Regulatory liabilities	47	2	28
Consumers revenues to be refunded	15
Consumers Energy Company | Voluntary refund mechanism
Disaggregation of Revenue [Line Items]
Regulatory liabilities	22
Accounts Receivable
Disaggregation of Revenue [Line Items]
Bad debt expense	50	22	33
Accounts Receivable | Consumers Energy Company
Disaggregation of Revenue [Line Items]
Bad debt expense	$ 50	$ 22	$ 33