Financings and Capitalization (First Mortgage Bond Purchase) (Details) - USD ($) $ in Millions	1 Months Ended
	May 31, 2023	Jun. 30, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Principal (In Millions)		$ 2,410
Gain on debt extinguishment	$ 84
Long-term debt		13,925	$ 13,122
Consumers Energy Company
Debt Instrument [Line Items]
Principal (In Millions)		1,525
Related Party | Consumers Energy Company
Debt Instrument [Line Items]
Long-term debt		235	$ 0
CMS Energy
Debt Instrument [Line Items]
Payment for purchase of first mortgage bonds	150
Principal (In Millions)		$ 800
2.650% First Mortgage Bonds Due 2052 | First mortgage bonds | Consumers Energy Company
Debt Instrument [Line Items]
Principal (In Millions)	$ 88
Interest rate	2.65%
2.500% First Mortgage Bonds Due 2060 | First mortgage bonds | Consumers Energy Company
Debt Instrument [Line Items]
Principal (In Millions)	$ 150
Interest rate	2.50%