Financings and Capitalization (First Mortgage Bond Purchase) (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended	9 Months Ended
	Oct. 26, 2023	Sep. 30, 2023	Sep. 30, 2023	Aug. 31, 2023	May 31, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Principal (In Millions)		$ 2,910	$ 2,910
Gain on debt extinguishment		17	101
Long-term debt		14,114	14,114			$ 13,122
Consumers Energy Company
Debt Instrument [Line Items]
Repayments of debt			1,625
Principal (In Millions)		2,025	2,025
Related Party | Consumers Energy Company
Debt Instrument [Line Items]
Long-term debt		294	294			$ 0
CMS Energy
Debt Instrument [Line Items]
Payment for purchase of first mortgage bonds			192
Principal (In Millions)		800	800
Term Loan Facility Due 2023 | Subsequent Event | NorthStar Clean Energy
Debt Instrument [Line Items]
Repayments of debt	$ 66
First mortgage bonds due 2060 | First mortgage bonds | Consumers Energy Company
Debt Instrument [Line Items]
Principal (In Millions)					$ 150
Interest rate					2.50%
First mortgage bonds due 2052 | First mortgage bonds | Consumers Energy Company
Debt Instrument [Line Items]
Principal (In Millions)				$ 15	$ 88
Interest rate				2.65%	2.65%
First mortgage bonds due 2050 | First mortgage bonds | Consumers Energy Company
Debt Instrument [Line Items]
Principal (In Millions)		$ 18	$ 18	$ 23
Interest rate		3.10%	3.10%	3.75%
First mortgage bonds due 2051 | First mortgage bonds | Consumers Energy Company
Debt Instrument [Line Items]
Principal (In Millions)		$ 3	$ 3
Interest rate		3.50%	3.50%