Income Taxes (Summary of Loss and Credit Carryforwards) (Details) $ in Millions	Dec. 31, 2023 USD ($)
Operating Loss Carryforwards [Line Items]
General business credits	$ 356
Total tax attributes	428
Consumers Energy Company
Operating Loss Carryforwards [Line Items]
General business credits	122
Total tax attributes	175
State Tax Authority
Operating Loss Carryforwards [Line Items]
Local net operating loss carryforwards	69
State Tax Authority | Consumers Energy Company
Operating Loss Carryforwards [Line Items]
Local net operating loss carryforwards	53
Local Tax Authority
Operating Loss Carryforwards [Line Items]
Local net operating loss carryforwards	$ 3