Retirement Benefits (Schedule Of Plan Contributions) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Postretirement benefits contributions	$ 12	$ 712	$ 10
Consumers Energy Company
Defined Benefit Plan Disclosure [Line Items]
Postretirement benefits contributions	9	690	$ 7
DB Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Postretirement benefits contributions	0	700
DB Pension Plans | Consumers Energy Company
Defined Benefit Plan Disclosure [Line Items]
Postretirement benefits contributions	0	682
OPEB Plan
Defined Benefit Plan Disclosure [Line Items]
Postretirement benefits contributions	0	1
OPEB Plan | Consumers Energy Company
Defined Benefit Plan Disclosure [Line Items]
Postretirement benefits contributions	$ 0	$ 1