Leases - Assets and Liabilities of Lessee (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Operating leases
Right-of-use assets	$ 31	$ 26
Lease liabilities
Current lease liabilities	4	3
Noncurrent lease liabilities	27	25
Finance leases
Right-of-use assets	82	57
Lease liabilities
Current lease liabilities	9	6
Non-current lease liabilities	$ 68	$ 46
Weighted-average remaining lease term (in years)
Operating leases	20 years	23 years
Finance leases	18 years	12 years
Weighted-average discount rate
Operating leases	4.00%	4.00%
Finance leases	5.20%	1.70%
Finance lease liability	$ 77
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
Consumers Energy Company
Operating leases
Right-of-use assets	$ 27	$ 22
Lease liabilities
Current lease liabilities	4	3
Noncurrent lease liabilities	23	19
Finance leases
Right-of-use assets	58	57
Lease liabilities
Current lease liabilities	9	6
Non-current lease liabilities	$ 45	$ 46
Weighted-average remaining lease term (in years)
Operating leases	18 years	21 years
Finance leases	10 years	12 years
Weighted-average discount rate
Operating leases	3.90%	3.90%
Finance leases	1.60%	1.70%
Finance lease liability	$ 54
Related Party Lease
Lease liabilities
Current lease liabilities	1	$ 1
Weighted-average discount rate
Finance lease liability	$ 25	$ 25