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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

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