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New Accounting Standards (Details) - USD ($) $ in Millions | 6 Months Ended |
--- | --- | ---
Jun. 30, 2016 | Dec. 31, 2015
Unamortized debt issuance costs | $ 41 | $ 41
New Accounting Pronouncement, Early Adoption, Effect [Member] |  |
Excess tax benefit related to stock | 6 |
Retained Earnings (Accumulated Deficit) [Member] |  |
Cumulative effect of change in accounting principle | 33 |
Consumers Energy Company [Member] |  |
Unamortized debt issuance costs | 22 | $ 23
Consumers Energy Company [Member] | New Accounting Pronouncement, Early Adoption, Effect [Member] |  |
Excess tax benefit related to stock | $ 6 |

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