Regulatory Matters (Schedule Of The Components Of PSCR And GCR Over/(Under) Recoveries) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Public Utilities, General Disclosures [Line Items]
Accrued rate refunds	$ 20	$ 35
Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Accrued rate refunds	20	35
Consumers Energy Company | PSCR overrecoveries/underrecoveries
Public Utilities, General Disclosures [Line Items]
Accrued rate refunds	5	33
Consumers Energy Company | GCR overrecoveries/underrecoveries
Public Utilities, General Disclosures [Line Items]
Accrued rate refunds	$ 15	$ 2