Income Taxes (Reconciliation Of Beginning And Ending Uncertain Tax Benefits) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at beginning of period	$ 27	$ 25	$ 23
Additions for current-year tax positions	1	2	1
Additions for prior-year tax positions	1	0	3
Reductions for prior-year tax positions	(1)	0	(2)
Balance at end of period	28	27	25
Consumers Energy Company
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at beginning of period	34	31	34
Additions for current-year tax positions	3	3	1
Additions for prior-year tax positions	1	0	4
Reductions for prior-year tax positions	(2)	0	(8)
Balance at end of period	$ 36	$ 34	$ 31