Income Taxes (Schedule of Effective Income Rate Reconciliation) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Taxes [Line Items]
Income Before Income Taxes	$ 954	$ 902	$ 823
Income tax expense at statutory rate	200	189	173
Increase (decrease) in income taxes from:
State and local income taxes, net of federal effect	31	51	39
Renewable energy tax credits	(58)	(51)	(44)
TCJA excess deferred taxes	(40)	(65)	(50)
Taxes attributable to noncontrolling interests	17	5	5
Accelerated flow-through of regulatory tax benefits	0	(39)	(28)
Other, net	(3)	3	0
Income Tax Expense	$ 147	$ 93	$ 95
Effective tax rate	15.40%	10.30%	11.50%
Consumers Energy Company
Income Taxes [Line Items]
Income Before Income Taxes	$ 1,028	$ 1,085	$ 1,024
Income tax expense at statutory rate	216	228	215
Increase (decrease) in income taxes from:
State and local income taxes, net of federal effect	36	59	54
Renewable energy tax credits	(46)	(46)	(37)
TCJA excess deferred taxes	(40)	(65)	(50)
Accelerated flow-through of regulatory tax benefits	0	(39)	(28)
Other, net	(5)	3	2
Income Tax Expense	$ 161	$ 140	$ 156
Effective tax rate	15.70%	12.90%	15.20%
Consumers Energy Company | Non-Michigan Jurisdiction
Increase (decrease) in income taxes from:
State and local income taxes, net of federal effect	$ (13)