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Regulatory Matters (Schedule Of The Components Of PSCR And GCR Over/(Under) Recoveries) (Details) - USD ($)
$ in Millions
Dec. 31, 2016
Dec. 31, 2015
Public Utilities, General Disclosures [Line Items]    
Accrued rate refunds $ 21 $ 26
Consumers Energy Company [Member]    
Public Utilities, General Disclosures [Line Items]    
Accrued rate refunds 21 26
Consumers Energy Company [Member] | Power Supply Cost Recover (PSCR) [Member]    
Public Utilities, General Disclosures [Line Items]    
Accrued rate refunds 8 8
Consumers Energy Company [Member] | Gas Cost Recover (GCR) [Member]    
Public Utilities, General Disclosures [Line Items]    
Accrued rate refunds $ 13 $ 18