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Plant, Property, and Equipment (Public Utilities, Allowance for Funds Used During Construction, Schedule of Composite Rate Table) (Details) | 12 Months Ended
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Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013
Consumers Energy Company [Member] |  |  |
AFUDC capitalization rate | 7.10% | 7.20% | 7.30%

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- Definition Disclosure of the composite rate of allowance for funds used during construction (AFUDC). The composite AFUDC rate is the average of the electric, gas, and common rates used during the period. + References No definition available. + Details
Name: | cms_PublicUtilitiesAllowanceForFundsUsedDuringConstructionCompositeRate
Namespace Prefix: | cms_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

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- Details
Name: | dei_LegalEntityAxis=cms_ConsumersEnergyCompanyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |