Regulatory Matters (Schedule Of The Components Of PSCR And GCR Over/(Under) Recoveries) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Public Utilities, General Disclosures [Line Items]
Accrued gas revenue	$ 16	$ 0
Accrued rate refunds	4	33
Consumers Energy Company
Public Utilities, General Disclosures [Line Items]
Accrued gas revenue	16	0
Accrued rate refunds	4	33
Consumers Energy Company | PSCR overrecoveries
Public Utilities, General Disclosures [Line Items]
Accrued rate refunds	4	27
Consumers Energy Company | GCR overrecoveries
Public Utilities, General Disclosures [Line Items]
Accrued gas revenue	16	0
Accrued rate refunds	$ 0	$ 6