Regulatory Matters - (Narrative) (Details) - USD ($) $ in Millions	1 Months Ended				3 Months Ended			9 Months Ended
	Sep. 30, 2025	Mar. 31, 2025	Oct. 31, 2024	May 31, 2024	Sep. 30, 2025	Aug. 20, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Public Utilities, General Disclosures [Line Items]
Revenues					$ 2,021		$ 1,743	$ 6,306	$ 5,526
Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Revenues					1,913		$ 1,661	6,007	$ 5,291
Consumers Energy Company | J.H. Campbell Generating Units
Public Utilities, General Disclosures [Line Items]
Financial impact of emergency order	$ 27					$ 53
Revenues	17					$ 67
Consumers Energy Company | Service Restoration Cost Deferral Application
Public Utilities, General Disclosures [Line Items]
Regulatory asset	$ 54				$ 54			$ 54
Electric Rate Case
Public Utilities, General Disclosures [Line Items]
Amended requested annual rate increase			$ 277
Electric Rate Case | Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Requested annual rate increase				$ 325
Requested annual rate increase, as a percent				10.25%
Surcharge for the recovery of excess distribution investments		$ 22
Additional annual rate increase authorized		$ 176
Rate of return on equity authorized		9.90%
Electric Rate Case, First Component | Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Requested annual rate increase				$ 303
Electric Rate Case, Second Component | Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Surcharge for the recovery of excess distribution investments				$ 22