Income Taxes (Narrative) (Details) - USD ($) $ in Millions	1 Months Ended	9 Months Ended
	Apr. 30, 2024	Sep. 30, 2024	Sep. 30, 2023	Jun. 30, 2024
Income Tax Benefits [Line Items]
Deferred income taxes and investment tax credits		$ 103	$ 96
Consumers Energy Company
Income Tax Benefits [Line Items]
Deferred income taxes and investment tax credits		$ 99	$ 107
Consumers Energy Company | Renewable Energy Tax Credit
Income Tax Benefits [Line Items]
Deferred income taxes and investment tax credits	$ 37
Adjustment for production				$ 51