Retirement Benefits (Schedule Of Net Benefit Costs) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
DB Pension Plans
Defined Benefit Plan, Roll Forwards [Abstract]
Service cost	$ 9	$ 14	$ 32	$ 41
Interest cost	21	14	59	44
Expected return on plan assets	(51)	(51)	(155)	(155)
Amortization of
Net loss	5	25	32	76
Prior service cost (credit)	1	1	3	3
Settlement loss	2	1	6	4
Net periodic cost (credit)	(13)	4	(23)	13
DB Pension Plans | Consumers Energy Company
Defined Benefit Plan, Roll Forwards [Abstract]
Service cost	9	14	32	40
Interest cost	20	14	56	42
Expected return on plan assets	(48)	(49)	(147)	(147)
Amortization of
Net loss	5	24	30	73
Prior service cost (credit)	1	1	3	3
Settlement loss	2	1	6	4
Net periodic cost (credit)	(11)	5	(20)	15
OPEB Plan
Defined Benefit Plan, Roll Forwards [Abstract]
Service cost	4	5	13	14
Interest cost	7	6	21	17
Expected return on plan assets	(29)	(28)	(87)	(82)
Amortization of
Net loss	0	2	1	6
Prior service cost (credit)	(12)	(14)	(38)	(40)
Settlement loss	0	0	0	0
Net periodic cost (credit)	(30)	(29)	(90)	(85)
OPEB Plan | Consumers Energy Company
Defined Benefit Plan, Roll Forwards [Abstract]
Service cost	4	4	13	13
Interest cost	6	6	20	17
Expected return on plan assets	(26)	(26)	(80)	(77)
Amortization of
Net loss	0	2	0	6
Prior service cost (credit)	(13)	(12)	(38)	(38)
Settlement loss	0	0	0	0
Net periodic cost (credit)	$ (29)	$ (26)	$ (85)	$ (79)