Retirement Benefits (Schedule Of Funded Status Of Retirement Benefit Plans) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
DB Pension Plans
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation at beginning of period	$ 3,070	$ 3,266
Service cost	41	53
Interest cost	81	60
Plan amendments	0	0
Actuarial gain	(811)	(108)
Benefits paid	(212)	(201)
Benefit obligation at end of period	2,169	3,070	$ 3,266
Defined Benefit Plan, Roll Forwards [Abstract]
Plan assets at fair value at beginning of period	3,599	3,402
Actual return on plan assets	(567)	398
Company contribution	0	0
Actual benefits paid	(212)	(201)
Plan assets at fair value at end of period	2,820	3,599	3,402
Funded status	651	529
DB Pension Plans | Consumers Energy Company
Defined Benefit Plan, Roll Forwards [Abstract]
Funded status	632	510
DB SERP
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation at beginning of period	149	160
Service cost	0	0
Interest cost	3	3
Plan amendments	0	0
Actuarial gain	(25)	(4)
Benefits paid	(10)	(10)
Benefit obligation at end of period	117	149	160
Defined Benefit Plan, Roll Forwards [Abstract]
Plan assets at fair value at beginning of period	0	0
Actual return on plan assets	0	0
Company contribution	10	10
Actual benefits paid	(10)	(10)
Plan assets at fair value at end of period	0	0	0
Funded status	(117)	(149)
DB SERP | Consumers Energy Company
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation at beginning of period	109	117
Service cost	0	0
Interest cost	2	2
Plan amendments	0	0
Actuarial gain	(19)	(3)
Benefits paid	(7)	(7)
Benefit obligation at end of period	85	109	117
Defined Benefit Plan, Roll Forwards [Abstract]
Plan assets at fair value at beginning of period	0	0
Actual return on plan assets	0	0
Company contribution	7	7
Actual benefits paid	(7)	(7)
Plan assets at fair value at end of period	0	0	0
Funded status	(85)	(109)
OPEB Plan
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation at beginning of period	1,166	1,205
Service cost	17	18	16
Interest cost	28	23	33
Plan amendments	0	5
Actuarial gain	(274)	(32)
Benefits paid	(48)	(53)
Benefit obligation at end of period	889	1,166	1,205
Defined Benefit Plan, Roll Forwards [Abstract]
Plan assets at fair value at beginning of period	1,787	1,645
Actual return on plan assets	(294)	194
Company contribution	0	0
Actual benefits paid	(47)	(52)
Plan assets at fair value at end of period	1,446	1,787	1,645
Funded status	557	621
OPEB Plan | Consumers Energy Company
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation at beginning of period	1,122	1,158
Service cost	17	17	15
Interest cost	27	23	31
Plan amendments	0	5
Actuarial gain	(265)	(30)
Benefits paid	(45)	(51)
Benefit obligation at end of period	856	1,122	1,158
Defined Benefit Plan, Roll Forwards [Abstract]
Plan assets at fair value at beginning of period	1,668	1,535
Actual return on plan assets	(273)	182
Company contribution	0	0
Actual benefits paid	(45)	(49)
Plan assets at fair value at end of period	1,350	1,668	$ 1,535
Funded status	$ 494	$ 546