Income Taxes (Schedule Of Effective Income Rate Reconciliation) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Taxes [Line Items]
Income from continuing operations before income taxes	$ 823	$ 809	$ 764
Income tax expense at statutory rate	173	170	160
Increase (decrease) in income taxes from:
State and local income taxes, net of federal effect	39	44	46
TCJA excess deferred taxes	(50)	(35)	(31)
Production tax credits	(40)	(28)	(20)
Accelerated flow-through of regulatory tax benefits	(28)	(13)	(13)
Research and development tax credits, net	(3)	(11)	(2)
Refund of alternative minimum tax sequestration	0	(9)	0
Other, net	4	(3)	(9)
Income tax expense	$ 95	$ 115	$ 131
Effective tax rate	11.50%	14.20%	17.10%
Consumers Energy Company
Income Taxes [Line Items]
Income from continuing operations before income taxes	$ 1,024	$ 989	$ 928
Income tax expense at statutory rate	215	208	195
Increase (decrease) in income taxes from:
State and local income taxes, net of federal effect	54	47	53
TCJA excess deferred taxes	(50)	(35)	(31)
Production tax credits	(33)	(19)	(12)
Accelerated flow-through of regulatory tax benefits	(28)	(13)	(13)
Research and development tax credits, net	(3)	(11)	(2)
Other, net	1	(4)	(5)
Income tax expense	$ 156	$ 173	$ 185
Effective tax rate	15.20%	17.50%	19.90%
Research Tax Credit Carryforward
Increase (decrease) in income taxes from:
Increase (decrease) in tax credit carryforward		$ 9
Research Tax Credit Carryforward | Consumers Energy Company
Increase (decrease) in income taxes from:
Increase (decrease) in tax credit carryforward		$ 8