Regulatory Matters (Schedule of Regulatory Assets and Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Public Utilities, General Disclosures [Line Items]
Total current regulatory assets	$ 229	$ 203
Total non-current regulatory assets	3,569	3,683
Total current regulatory liabilities	111	56
Total non-current regulatory liabilities	4,067	3,894
Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Total current regulatory assets	229	203
Total non-current regulatory assets	3,569	3,683
Total regulatory assets	3,798	3,886
Total current regulatory liabilities	111	56
Total non-current regulatory liabilities	4,067	3,894
Total regulatory liabilities	4,178	3,950
Income taxes, net | Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Total current regulatory liabilities	53	49
Total non-current regulatory liabilities	1,163	1,220
ASP gain | Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Total current regulatory liabilities	47	0
Total non-current regulatory liabilities	46	0
Other | Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Total current regulatory liabilities	11	7
Total non-current regulatory liabilities	24	20
Cost of removal | Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Total non-current regulatory liabilities	2,665	2,545
Renewable energy plan | Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Total non-current regulatory liabilities	51	29
Energy waste reduction plan | Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Total non-current regulatory liabilities	41	25
Renewable energy grant | Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Total non-current regulatory liabilities	40	43
Postretirement benefits expense deferral mechanism | Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Total non-current regulatory liabilities	37	12
2022 PSCR underrecovery | Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Total current regulatory assets	126	126
Total non-current regulatory assets	0	126
Energy waste reduction plan incentive | Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Total current regulatory assets	60	54
Total non-current regulatory assets	64	58
Retention incentive program | Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Total current regulatory assets	18	12
Total non-current regulatory assets	12	27
Other | Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Total current regulatory assets	25	11
Total non-current regulatory assets	25	26
Costs of coal-fueled electric generating units to be retired | Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Total non-current regulatory assets	1,266	1,265
Postretirement benefits | Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Total non-current regulatory assets	747	741
Securitized costs | Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Total non-current regulatory assets	666	778
ARO | Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Total non-current regulatory assets	366	328
Decommissioning costs | Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Total non-current regulatory assets	158	83
Unamortized loss on reacquired debt | Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Total non-current regulatory assets	92	96
MGP sites | Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Total non-current regulatory assets	90	99
Energy waste reduction plan | Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Total non-current regulatory assets	31	19
Ludington overhaul contract dispute | Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Total non-current regulatory assets	31	13
Postretirement benefits expense deferral mechanism | Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Total non-current regulatory assets	$ 21	$ 24