Retirement Benefits (Schedule Of Net Periodic Benefit Cost Not yet Recognized) (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Consumers Energy Company
Regulatory assets (liabilities)
Total regulatory assets	$ 3,652	$ 2,305
Total regulatory liabilities	(3,900)	(3,948)
DB Pension Plans and DB SERP
Regulatory assets (liabilities)
Net loss	724	812
Prior service cost (credit)	21	25
Total regulatory assets	745	837
AOCI
Net loss (gain)	69	94
Prior service cost (credit)	1	0
Total amounts recognized in regulatory assets (liabilities) and AOCI	815	931
DB Pension Plans and DB SERP | Consumers Energy Company
Regulatory assets (liabilities)
Net loss	724	812
Prior service cost (credit)	21	25
Total regulatory assets	745	837
AOCI
Net loss (gain)	20	41
Total amounts recognized in regulatory assets (liabilities) and AOCI	765	878
OPEB Plan
Regulatory assets (liabilities)
Net loss	251	136
Prior service cost (credit)	(140)	(190)
Total regulatory assets	111
Total regulatory liabilities		(54)
AOCI
Net loss (gain)	2	(17)
Prior service cost (credit)	(3)	(5)
Total amounts recognized in regulatory assets (liabilities) and AOCI	110	(76)
OPEB Plan | Consumers Energy Company
Regulatory assets (liabilities)
Net loss	251	136
Prior service cost (credit)	(140)	(190)
Total regulatory assets	111
Total regulatory liabilities		(54)
AOCI
Net loss (gain)	0	0
Total amounts recognized in regulatory assets (liabilities) and AOCI	$ 111	$ (54)