Retirement Benefits (Schedule Of Net Benefit Costs) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
DB Pension Plans
Defined Benefit Plan, Roll Forwards [Abstract]
Service cost	$ 8	$ 11	$ 15	$ 23
Interest cost	26	20	53	38
Expected return on plan assets	(55)	(52)	(110)	(104)
Amortization of
Net loss	3	10	6	27
Prior service cost (credit)	1	1	2	2
Settlement loss	3	2	5	4
Net periodic credit	(14)	(8)	(29)	(10)
DB Pension Plans | Volatility Mechanism
Amortization of
Deferred costs (credits)			6
DB Pension Plans | Consumers Energy Company
Defined Benefit Plan, Roll Forwards [Abstract]
Service cost	7	11	14	23
Interest cost	26	20	51	36
Expected return on plan assets	(52)	(50)	(104)	(99)
Amortization of
Net loss	2	9	5	25
Prior service cost (credit)	1	1	2	2
Settlement loss	3	2	5	4
Net periodic credit	(13)	(7)	(27)	(9)
OPEB Plan
Defined Benefit Plan, Roll Forwards [Abstract]
Service cost	3	5	6	9
Interest cost	11	7	22	14
Expected return on plan assets	(25)	(29)	(51)	(58)
Amortization of
Net loss	3	1	6	1
Prior service cost (credit)	(11)	(14)	(21)	(26)
Settlement loss	0	0	0	0
Net periodic credit	(19)	(30)	(38)	(60)
OPEB Plan | Volatility Mechanism
Amortization of
Deferred costs (credits)			(12)
OPEB Plan | Consumers Energy Company
Defined Benefit Plan, Roll Forwards [Abstract]
Service cost	3	5	6	9
Interest cost	10	7	21	14
Expected return on plan assets	(24)	(27)	(48)	(54)
Amortization of
Net loss	3	0	6	0
Prior service cost (credit)	(10)	(13)	(20)	(25)
Settlement loss	0	0	0	0
Net periodic credit	$ (18)	$ (28)	$ (35)	$ (56)