Retirement Benefits (Schedule Of Net Benefit Costs) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
DB Pension Plans
Defined Benefit Plan, Roll Forwards [Abstract]
Service cost	$ 11	$ 13	$ 23	$ 27
Interest cost	20	15	38	30
Expected return on plan assets	(52)	(52)	(104)	(104)
Amortization of
Net loss	10	26	27	51
Prior service cost (credit)	1	1	2	2
Settlement loss	2	2	4	3
Net periodic cost (credit)	(8)	5	(10)	9
DB Pension Plans | Consumers Energy Company
Defined Benefit Plan, Roll Forwards [Abstract]
Service cost	11	13	23	26
Interest cost	20	14	36	28
Expected return on plan assets	(50)	(49)	(99)	(98)
Amortization of
Net loss	9	24	25	49
Prior service cost (credit)	1	1	2	2
Settlement loss	2	2	4	3
Net periodic cost (credit)	(7)	5	(9)	10
OPEB Plan
Defined Benefit Plan, Roll Forwards [Abstract]
Service cost	5	5	9	9
Interest cost	7	5	14	11
Expected return on plan assets	(29)	(27)	(58)	(54)
Amortization of
Net loss	1	2	1	4
Prior service cost (credit)	(14)	(13)	(26)	(26)
Settlement loss	0	0	0	0
Net periodic cost (credit)	(30)	(28)	(60)	(56)
OPEB Plan | Consumers Energy Company
Defined Benefit Plan, Roll Forwards [Abstract]
Service cost	5	5	9	9
Interest cost	7	5	14	11
Expected return on plan assets	(27)	(26)	(54)	(51)
Amortization of
Net loss	0	2	0	4
Prior service cost (credit)	(13)	(13)	(25)	(26)
Settlement loss	0	0	0	0
Net periodic cost (credit)	$ (28)	$ (27)	$ (56)	$ (53)