Income Taxes (Loss And Credit Carryforwards) (Details) $ in Millions	Dec. 31, 2021 USD ($)
Operating Loss Carryforwards [Line Items]
General business credits	$ 264
Total tax attributes	332
Consumers Energy Company
Operating Loss Carryforwards [Line Items]
General business credits	83
Total tax attributes	134
Federal Tax Authority
Operating Loss Carryforwards [Line Items]
Federal net operating loss carryforwards	3
Charitable contribution carryforwards	6
Federal Tax Authority | Consumers Energy Company
Operating Loss Carryforwards [Line Items]
Federal net operating loss carryforwards	2
Charitable contribution carryforwards	5
State Tax Authority
Operating Loss Carryforwards [Line Items]
Local net operating loss carryforwards	55
Charitable contribution carryforwards	1
State Tax Authority | Consumers Energy Company
Operating Loss Carryforwards [Line Items]
Local net operating loss carryforwards	43
Charitable contribution carryforwards	1
Local Tax Authority
Operating Loss Carryforwards [Line Items]
Local net operating loss carryforwards	$ 3