Income Taxes (Schedule of Reconciliation of Uncertain Tax Benefits) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at beginning of period	$ 26	$ 28	$ 27
Additions for current-year tax positions	1	1	1
Additions for prior-year tax positions	2	0	1
Reductions for prior-year tax positions	0	0	(1)
Reductions for lapse of statute of limitations	(5)	(3)	0
Balance at end of period	24	26	28
Consumers Energy Company
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at beginning of period	36	36	34
Additions for current-year tax positions	6	1	3
Additions for prior-year tax positions	1	2	1
Reductions for prior-year tax positions	0	0	(2)
Reductions for lapse of statute of limitations	(11)	(3)	0
Balance at end of period	$ 32	$ 36	$ 36