Leases (Summary of Minimum Annual Rental Commitments) (Details) $ in Millions	Dec. 31, 2023 USD ($)
Operating Leases
2024	$ 5
2025	4
2026	3
2027	2
2028	1
2028 and thereafter	30
Total minimum lease payments	45
Less discount	19
Present value of minimum lease payments	26
Finance Leases
2024	19
2025	16
2026	17
2027	14
2028	14
2028 and thereafter	92
Total minimum lease payments	172
Less discount	105
Present value of minimum lease payments	67
Consumers Energy Company
Operating Leases
2024	5
2025	4
2026	2
2027	2
2028	1
2028 and thereafter	24
Total minimum lease payments	38
Less discount	15
Present value of minimum lease payments	23
Finance Leases
2024	18
2025	15
2026	15
2027	13
2028	13
2028 and thereafter	34
Total minimum lease payments	108
Less discount	64
Present value of minimum lease payments	44
Pipelines and PPAs
Finance Leases
2024	13
2025	13
2026	13
2027	13
2028	13
2028 and thereafter	26
Total minimum lease payments	91
Less discount	62
Present value of minimum lease payments	29
Pipelines and PPAs | Consumers Energy Company
Finance Leases
2024	13
2025	13
2026	13
2027	13
2028	13
2028 and thereafter	26
Total minimum lease payments	91
Less discount	62
Present value of minimum lease payments	29
Other
Finance Leases
2024	6
2025	3
2026	4
2027	1
2028	1
2028 and thereafter	66
Total minimum lease payments	81
Less discount	43
Present value of minimum lease payments	38
Other | Consumers Energy Company
Finance Leases
2024	5
2025	2
2026	2
2027	0
2028	0
2028 and thereafter	8
Total minimum lease payments	17
Less discount	2
Present value of minimum lease payments	$ 15