Leases (Schedule of Lessee Cash Flows) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Cash paid for amounts included in the measurement of lease liabilities
Cash used in operating activities for operating leases	$ 6	$ 6
Cash used in operating activities for finance leases	15	14
Cash used in financing activities for finance leases	8	13
Lease liabilities arising from obtaining right-of-use assets
Operating leases	1	10
Finance leases	0	36
Consumers Energy Company
Cash paid for amounts included in the measurement of lease liabilities
Cash used in operating activities for operating leases	6	6
Cash used in operating activities for finance leases	13	14
Cash used in financing activities for finance leases	8	12
Lease liabilities arising from obtaining right-of-use assets
Operating leases	1	10
Finance leases	$ 0	$ 12