Regulatory Matters (Schedule of Regulatory Assets and Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Public Utilities, General Disclosures [Line Items]
Total current regulatory assets	$ 203	$ 57
Total non-current regulatory assets	3,683	3,595
Total current regulatory liabilities	56	104
Total non-current regulatory liabilities	3,894	3,796
Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Total current regulatory assets	203	57
Total non-current regulatory assets	3,683	3,595
Total regulatory assets	3,886	3,652
Total current regulatory liabilities	56	104
Total non-current regulatory liabilities	3,894	3,796
Total regulatory liabilities	3,950	3,900
Income taxes, net | Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Total current regulatory liabilities	49	48
Total non-current regulatory liabilities	1,220	1,267
Reserve for customer refunds | Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Total current regulatory liabilities	2	47
Total regulatory liabilities	15
Other | Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Total current regulatory liabilities	5	9
Total non-current regulatory liabilities	20	20
Cost of removal | Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Total non-current regulatory liabilities	2,545	2,426
Renewable energy grant | Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Total non-current regulatory liabilities	43	45
Renewable energy plan | Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Total non-current regulatory liabilities	29	32
Energy waste reduction plan | Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Total non-current regulatory liabilities	25	6
Postretirement benefits expense deferral mechanism | Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Total non-current regulatory liabilities	12	0
2022 PSCR underrecovery | Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Total current regulatory assets	126	0
Total non-current regulatory assets	126	0
Energy Waste Reduction Plan Incentive | Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Total current regulatory assets	54	47
Total non-current regulatory assets		55
Retention incentive program | Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Total current regulatory assets	12	2
Total non-current regulatory assets	27	31
Other | Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Total current regulatory assets	11	8
Total non-current regulatory assets	26	29
Costs of coal-fueled electric generating units to be retired | Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Total non-current regulatory assets	1,265	1,258
Securitized costs | Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Total non-current regulatory assets	778	843
Postretirement benefits | Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Total non-current regulatory assets	741	856
ARO | Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Total non-current regulatory assets	328	281
MGP sites | Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Total non-current regulatory assets	99	108
Unamortized loss on reacquired debt | Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Total non-current regulatory assets	96	100
Decommissioning costs | Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Total non-current regulatory assets	83	24
Postretirement benefits expense deferral mechanism | Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Total non-current regulatory assets	24	0
Ludington overhaul contract dispute | Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Total non-current regulatory assets	13	0
Energy waste reduction plan | Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Total non-current regulatory assets	$ 19	$ 10