Income Taxes (Schedule of Reconciliation of Uncertain Tax Benefits) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at beginning of period	$ 28	$ 27	$ 25
Additions for current-year tax positions	1	1	2
Additions for prior-year tax positions	0	1	0
Reductions for prior-year tax positions	(3)	(1)	0
Balance at end of period	26	28	27
Consumers Energy Company
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at beginning of period	36	34	31
Additions for current-year tax positions	1	3	3
Additions for prior-year tax positions	2	1	0
Reductions for prior-year tax positions	(3)	(2)	0
Balance at end of period	$ 36	$ 36	$ 34