Retirement Benefits (Schedule Of Net Benefit Costs) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
DB Pension Plans
Defined Benefit Plan, Roll Forwards [Abstract]
Service cost	$ 7	$ 12
Interest cost	27	18
Expected return on plan assets	(55)	(52)
Amortization of
Net loss	3	17
Prior service cost (credit)	1	1
Settlement loss	2	2
Net periodic credit	(15)	(2)
DB Pension Plans | Volatility Mechanism
Amortization of
Deferred costs (credits)	3
DB Pension Plans | Consumers Energy Company
Defined Benefit Plan, Roll Forwards [Abstract]
Service cost	7	12
Interest cost	25	16
Expected return on plan assets	(52)	(49)
Amortization of
Net loss	3	16
Prior service cost (credit)	1	1
Settlement loss	2	2
Net periodic credit	(14)	(2)
OPEB Plan
Defined Benefit Plan, Roll Forwards [Abstract]
Service cost	3	4
Interest cost	11	7
Expected return on plan assets	(26)	(29)
Amortization of
Net loss	3	0
Prior service cost (credit)	(10)	(12)
Settlement loss	0	0
Net periodic credit	(19)	(30)
OPEB Plan | Volatility Mechanism
Amortization of
Deferred costs (credits)	(6)
OPEB Plan | Consumers Energy Company
Defined Benefit Plan, Roll Forwards [Abstract]
Service cost	3	4
Interest cost	11	7
Expected return on plan assets	(24)	(27)
Amortization of
Net loss	3	0
Prior service cost (credit)	(10)	(12)
Settlement loss	0	0
Net periodic credit	$ (17)	$ (28)