Leases (Summary of Lease Right-of-Use Assets and Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Lessor, Lease, Description [Line Items]
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]	Other	Other
Operating Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Other current liabilities	Other current liabilities
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]	Other non‑current liabilities	Other non‑current liabilities
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]	Plant, property, and equipment, net	Plant, property, and equipment, net
Finance Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Current portion of long-term debt and finance leases	Current portion of long-term debt and finance leases
Operating leases
Right-of-use assets	$ 24	$ 26
Lease liabilities
Current lease liabilities	3	4
Noncurrent lease liabilities	21	22
Finance leases
Right-of-use assets	119	71
Lease liabilities
Current lease liabilities	4	5
Non-current lease liabilities	$ 112	$ 62
Weighted-average remaining lease term (in years)
Operating leases	20 years	19 years
Finance leases	26 years	19 years
Weighted-average discount rate
Operating leases	5.30%	5.20%
Finance leases	5.80%	5.30%
Finance lease liability	$ 116
Consumers Energy Company
Operating leases
Right-of-use assets	20	$ 23
Lease liabilities
Current lease liabilities	3	4
Noncurrent lease liabilities	17	19
Finance leases
Right-of-use assets	76	48
Lease liabilities
Current lease liabilities	4	5
Non-current lease liabilities	$ 69	$ 39
Weighted-average remaining lease term (in years)
Operating leases	19 years	18 years
Finance leases	22 years	11 years
Weighted-average discount rate
Operating leases	5.40%	5.30%
Finance leases	4.80%	1.50%
Finance lease liability	$ 73
Related Party Lease
Lease liabilities
Current lease liabilities	1	$ 1
Weighted-average discount rate
Finance lease liability	$ 23	$ 23