Related party Transactions - Consumers (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Nov. 30, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Consumers Energy Company
Related Party Transaction [Line Items]
Purchased power – related parties		$ 75	$ 76	$ 77
Long-term purchase commitment, amount	$ 20
Consumers Energy Company | Related Party
Related Party Transaction [Line Items]
Due to related parties		19	20
Accounts receivable related parties		9	$ 8
Consumers Energy Company | Credit Agreement | Related Party
Related Party Transaction [Line Items]
Maximum borrowing capacity		$ 500
CMS Energy Note Payable
Related Party Transaction [Line Items]
Interest rate		4.10%
CMS Energy Note Payable | Consumers Energy Company
Related Party Transaction [Line Items]
Interest rate		4.10%