Leases - Schedule of Lease Costs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Lessee, Lease, Description [Line Items]
Operating lease costs	$ 6	$ 8
Finance lease costs
Amortization of right-of-use assets	12	7
Interest on lease liabilities	14	16
Variable lease costs	93	90
Short-term lease costs	23	22
Total lease costs	148	143
Consumers Energy Company
Lessee, Lease, Description [Line Items]
Operating lease costs	6	8
Finance lease costs
Amortization of right-of-use assets	12	7
Interest on lease liabilities	14	16
Variable lease costs	93	90
Short-term lease costs	22	21
Total lease costs	$ 147	$ 142