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Plant, Property, and Equipment (Property, Plant and Equipment Table) (Details) (USD $) In Millions, unless otherwise specified | 12 Months Ended |
--- | --- | ---
Dec. 31, 2014 site | Dec. 31, 2013 | Dec. 31, 2012
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Construction work in progress | $ 1,106 us-gaap_ConstructionInProgressGross |  | $ 1,149 us-gaap_ConstructionInProgressGross |  |
Accumulated Depreciation and Amortization | (5,415)us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment |  | (5,087)us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment |  |
Total plant, property, and equipment | 13,412 us-gaap_PropertyPlantAndEquipmentNet | [1] | 12,246 us-gaap_PropertyPlantAndEquipmentNet | [1] |
Public Utilities, Property Plant and Equipment Additions | 1,600 cms_PublicUtilitiesPropertyPlantAndEquipmentAdditions |  | 1,300 cms_PublicUtilitiesPropertyPlantAndEquipmentAdditions |  |
Public Utilities, Property Plant and Equipment Disposals | 126 cms_PublicUtilitiesPropertyPlantAndEquipmentDisposals |  | 156 cms_PublicUtilitiesPropertyPlantAndEquipmentDisposals |  |
Consumers Energy Company [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Capital Leased Assets, Gross | 295 us-gaap_CapitalLeasedAssetsGross / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember |  | 291 us-gaap_CapitalLeasedAssetsGross / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember |  | 285 us-gaap_CapitalLeasedAssetsGross / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember
Construction work in progress | 1,103 us-gaap_PublicUtilitiesPropertyPlantAndEquipmentConstructionWorkInProgress / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember |  | 1,147 us-gaap_PublicUtilitiesPropertyPlantAndEquipmentConstructionWorkInProgress / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember |  |
Less accumulated depreciation and amortization | (5,346)us-gaap_PublicUtilitiesPropertyPlantAndEquipmentAccumulatedDepreciation / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember |  | (5,022)us-gaap_PublicUtilitiesPropertyPlantAndEquipmentAccumulatedDepreciation / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember |  |
Total plant, property, and equipment | 13,337 us-gaap_PublicUtilitiesPropertyPlantAndEquipmentNet / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember | [1] | 12,169 us-gaap_PublicUtilitiesPropertyPlantAndEquipmentNet / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember | [1] |
Public Utilities, Property Plant and Equipment Additions | 1,600 cms_PublicUtilitiesPropertyPlantAndEquipmentAdditions / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember |  | 1,300 cms_PublicUtilitiesPropertyPlantAndEquipmentAdditions / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember |  |
Public Utilities, Property Plant and Equipment Disposals | 126 cms_PublicUtilitiesPropertyPlantAndEquipmentDisposals / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember |  | 156 cms_PublicUtilitiesPropertyPlantAndEquipmentDisposals / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember |  |
Number of units planned to be retired | 10 cms_NumberOfUnitsPlannedToBeRetired / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember |  |  |  |
Electricity Generation Plant, Non-Nuclear [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Public Utilities, Property, Plant and Equipment, Generation or Processing | 4,544 us-gaap_PublicUtilitiesPropertyPlantAndEquipmentGenerationOrProcessing / us-gaap_PublicUtilityAxis = us-gaap_ElectricityGenerationPlantNonNuclearMember |  | 3,992 us-gaap_PublicUtilitiesPropertyPlantAndEquipmentGenerationOrProcessing / us-gaap_PublicUtilityAxis = us-gaap_ElectricityGenerationPlantNonNuclearMember |  |
Electricity Generation Plant, Non-Nuclear [Member] | Minimum [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Estimated Depreciable Life in Years, Generation | 22 years |  |  |  |
Electricity Generation Plant, Non-Nuclear [Member] | Maximum [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Estimated Depreciable Life in Years, Generation | 125 years |  |  |  |
Electricity Generation Plant, Non-Nuclear [Member] | Consumers Energy Company [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Public Utilities, Property, Plant and Equipment, Generation or Processing | 4,544 us-gaap_PublicUtilitiesPropertyPlantAndEquipmentGenerationOrProcessing / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_PublicUtilityAxis = us-gaap_ElectricityGenerationPlantNonNuclearMember |  | 3,992 us-gaap_PublicUtilitiesPropertyPlantAndEquipmentGenerationOrProcessing / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_PublicUtilityAxis = us-gaap_ElectricityGenerationPlantNonNuclearMember |  |
Electricity Generation Plant, Non-Nuclear [Member] | Consumers Energy Company [Member] | Minimum [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Estimated Depreciable Life in Years, Generation | 22 years |  |  |  |
Electricity Generation Plant, Non-Nuclear [Member] | Consumers Energy Company [Member] | Maximum [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Estimated Depreciable Life in Years, Generation | 125 years |  |  |  |
Electric Distribution [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Public Utilities, Property, Plant and Equipment, Distribution | 6,487 us-gaap_PublicUtilitiesPropertyPlantAndEquipmentDistribution / us-gaap_PublicUtilityAxis = us-gaap_ElectricDistributionMember |  | 6,140 us-gaap_PublicUtilitiesPropertyPlantAndEquipmentDistribution / us-gaap_PublicUtilityAxis = us-gaap_ElectricDistributionMember |  |
Electric Distribution [Member] | Minimum [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Estimated Depreciable Life in Years, Distribution | 23 years |  |  |  |
Electric Distribution [Member] | Maximum [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Estimated Depreciable Life in Years, Distribution | 75 years |  |  |  |
Electric Distribution [Member] | Consumers Energy Company [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Public Utilities, Property, Plant and Equipment, Distribution | 6,487 us-gaap_PublicUtilitiesPropertyPlantAndEquipmentDistribution / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_PublicUtilityAxis = us-gaap_ElectricDistributionMember |  | 6,140 us-gaap_PublicUtilitiesPropertyPlantAndEquipmentDistribution / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_PublicUtilityAxis = us-gaap_ElectricDistributionMember |  |
Electric Distribution [Member] | Consumers Energy Company [Member] | Minimum [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Estimated Depreciable Life in Years, Distribution | 23 years |  |  |  |
Electric Distribution [Member] | Consumers Energy Company [Member] | Maximum [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Estimated Depreciable Life in Years, Distribution | 75 years |  |  |  |
Electric Other [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment | 910 us-gaap_PublicUtilitiesPropertyPlantAndEquipmentOtherPropertyPlantAndEquipment / us-gaap_PublicUtilityAxis = cms_ElectricOtherMember |  | 770 us-gaap_PublicUtilitiesPropertyPlantAndEquipmentOtherPropertyPlantAndEquipment / us-gaap_PublicUtilityAxis = cms_ElectricOtherMember |  |
Electric Other [Member] | Minimum [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Estimated Depreciable Life in Years, Other | 5 years |  |  |  |
Electric Other [Member] | Maximum [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Estimated Depreciable Life in Years, Other | 50 years |  |  |  |
Electric Other [Member] | Consumers Energy Company [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment | 910 us-gaap_PublicUtilitiesPropertyPlantAndEquipmentOtherPropertyPlantAndEquipment / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_PublicUtilityAxis = cms_ElectricOtherMember |  | 770 us-gaap_PublicUtilitiesPropertyPlantAndEquipmentOtherPropertyPlantAndEquipment / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_PublicUtilityAxis = cms_ElectricOtherMember |  |
Electric Other [Member] | Consumers Energy Company [Member] | Minimum [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Estimated Depreciable Life in Years, Other | 5 years |  |  |  |
Electric Other [Member] | Consumers Energy Company [Member] | Maximum [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Estimated Depreciable Life in Years, Other | 50 years |  |  |  |
Electric Capital Leases [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Capital Leased Assets, Gross | 289 us-gaap_CapitalLeasedAssetsGross / us-gaap_PublicUtilityAxis = cms_ElectricCapitalLeasesMember |  | 284 us-gaap_CapitalLeasedAssetsGross / us-gaap_PublicUtilityAxis = cms_ElectricCapitalLeasesMember |  |
Electric Capital Leases [Member] | Consumers Energy Company [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Capital Leased Assets, Gross | 289 us-gaap_CapitalLeasedAssetsGross / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_PublicUtilityAxis = cms_ElectricCapitalLeasesMember |  | 284 us-gaap_CapitalLeasedAssetsGross / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_PublicUtilityAxis = cms_ElectricCapitalLeasesMember |  |
Gas Distribution [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Public Utilities, Property, Plant and Equipment, Distribution | 3,239 us-gaap_PublicUtilitiesPropertyPlantAndEquipmentDistribution / us-gaap_PublicUtilityAxis = us-gaap_GasDistributionMember |  | 3,015 us-gaap_PublicUtilitiesPropertyPlantAndEquipmentDistribution / us-gaap_PublicUtilityAxis = us-gaap_GasDistributionMember |  |
Gas Distribution [Member] | Minimum [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Estimated Depreciable Life in Years, Distribution | 28 years |  |  |  |
Gas Distribution [Member] | Maximum [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Estimated Depreciable Life in Years, Distribution | 80 years |  |  |  |
Gas Distribution [Member] | Consumers Energy Company [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Public Utilities, Property, Plant and Equipment, Distribution | 3,239 us-gaap_PublicUtilitiesPropertyPlantAndEquipmentDistribution / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_PublicUtilityAxis = us-gaap_GasDistributionMember |  | 3,015 us-gaap_PublicUtilitiesPropertyPlantAndEquipmentDistribution / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_PublicUtilityAxis = us-gaap_GasDistributionMember |  |
Gas Distribution [Member] | Consumers Energy Company [Member] | Minimum [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Estimated Depreciable Life in Years, Distribution | 28 years |  |  |  |
Gas Distribution [Member] | Consumers Energy Company [Member] | Maximum [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Estimated Depreciable Life in Years, Distribution | 80 years |  |  |  |
Gas Transmission [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Public Utilities, Property, Plant and Equipment, Transmission | 974 us-gaap_PublicUtilitiesPropertyPlantAndEquipmentTransmission / us-gaap_PublicUtilityAxis = us-gaap_GasTransmissionMember |  | 821 us-gaap_PublicUtilitiesPropertyPlantAndEquipmentTransmission / us-gaap_PublicUtilityAxis = us-gaap_GasTransmissionMember |  |
Gas Transmission [Member] | Minimum [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Estimated Depreciable Life in Years, Transmission | 17 years |  |  |  |
Gas Transmission [Member] | Maximum [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Estimated Depreciable Life in Years, Transmission | 75 years |  |  |  |
Gas Transmission [Member] | Consumers Energy Company [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Public Utilities, Property, Plant and Equipment, Transmission | 974 us-gaap_PublicUtilitiesPropertyPlantAndEquipmentTransmission / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_PublicUtilityAxis = us-gaap_GasTransmissionMember |  | 821 us-gaap_PublicUtilitiesPropertyPlantAndEquipmentTransmission / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_PublicUtilityAxis = us-gaap_GasTransmissionMember |  |
Gas Transmission [Member] | Consumers Energy Company [Member] | Minimum [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Estimated Depreciable Life in Years, Transmission | 17 years |  |  |  |
Gas Transmission [Member] | Consumers Energy Company [Member] | Maximum [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Estimated Depreciable Life in Years, Transmission | 75 years |  |  |  |
Gas Underground Storage Facilities [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment | 578 us-gaap_PublicUtilitiesPropertyPlantAndEquipmentOtherPropertyPlantAndEquipment / us-gaap_PublicUtilityAxis = cms_GasUndergroundStorageFacilitiesMember | [2] | 535 us-gaap_PublicUtilitiesPropertyPlantAndEquipmentOtherPropertyPlantAndEquipment / us-gaap_PublicUtilityAxis = cms_GasUndergroundStorageFacilitiesMember | [2] |
Gas Underground Storage Facilities [Member] | Minimum [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Estimated Depreciable Life in Years, Other | 29 years | [2] |  |  |
Gas Underground Storage Facilities [Member] | Maximum [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Estimated Depreciable Life in Years, Other | 65 years | [2] |  |  |
Gas Underground Storage Facilities [Member] | Consumers Energy Company [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment | 578 us-gaap_PublicUtilitiesPropertyPlantAndEquipmentOtherPropertyPlantAndEquipment / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_PublicUtilityAxis = cms_GasUndergroundStorageFacilitiesMember | [2] | 535 us-gaap_PublicUtilitiesPropertyPlantAndEquipmentOtherPropertyPlantAndEquipment / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_PublicUtilityAxis = cms_GasUndergroundStorageFacilitiesMember | [2] |
Gas Underground Storage Facilities [Member] | Consumers Energy Company [Member] | Minimum [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Estimated Depreciable Life in Years, Other | 29 years | [2] |  |  |
Gas Underground Storage Facilities [Member] | Consumers Energy Company [Member] | Maximum [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Estimated Depreciable Life in Years, Other | 65 years | [2] |  |  |
Gas Other [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment | 538 us-gaap_PublicUtilitiesPropertyPlantAndEquipmentOtherPropertyPlantAndEquipment / us-gaap_PublicUtilityAxis = cms_GasOtherMember |  | 465 us-gaap_PublicUtilitiesPropertyPlantAndEquipmentOtherPropertyPlantAndEquipment / us-gaap_PublicUtilityAxis = cms_GasOtherMember |  |
Gas Other [Member] | Minimum [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Estimated Depreciable Life in Years, Other | 5 years |  |  |  |
Gas Other [Member] | Maximum [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Estimated Depreciable Life in Years, Other | 50 years |  |  |  |
Gas Other [Member] | Consumers Energy Company [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment | 538 us-gaap_PublicUtilitiesPropertyPlantAndEquipmentOtherPropertyPlantAndEquipment / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_PublicUtilityAxis = cms_GasOtherMember |  | 465 us-gaap_PublicUtilitiesPropertyPlantAndEquipmentOtherPropertyPlantAndEquipment / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_PublicUtilityAxis = cms_GasOtherMember |  |
Gas Other [Member] | Consumers Energy Company [Member] | Minimum [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Estimated Depreciable Life in Years, Other | 5 years |  |  |  |
Gas Other [Member] | Consumers Energy Company [Member] | Maximum [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Estimated Depreciable Life in Years, Other | 50 years |  |  |  |
Gas Capital Leases [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Capital Leased Assets, Gross | 6 us-gaap_CapitalLeasedAssetsGross / us-gaap_PublicUtilityAxis = cms_GasCapitalLeasesMember |  | 7 us-gaap_CapitalLeasedAssetsGross / us-gaap_PublicUtilityAxis = cms_GasCapitalLeasesMember |  |
Gas Capital Leases [Member] | Consumers Energy Company [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Capital Leased Assets, Gross | 6 us-gaap_CapitalLeasedAssetsGross / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_PublicUtilityAxis = cms_GasCapitalLeasesMember |  | 7 us-gaap_CapitalLeasedAssetsGross / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_PublicUtilityAxis = cms_GasCapitalLeasesMember |  |
Enterprises IPP [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Plant, property, and equipment, gross | 90 us-gaap_PropertyPlantAndEquipmentGross / us-gaap_PublicUtilityRegulatedOrUnregulatedStatusAxis = cms_EnterprisesIppMember |  | 89 us-gaap_PropertyPlantAndEquipmentGross / us-gaap_PublicUtilityRegulatedOrUnregulatedStatusAxis = cms_EnterprisesIppMember |  |
Enterprises IPP [Member] | Minimum [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Estimated Depreciable Life in Years, Other | 3 years |  |  |  |
Enterprises IPP [Member] | Maximum [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Estimated Depreciable Life in Years, Other | 30 years |  |  |  |
Enterprises Other [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Plant, property, and equipment, gross | 25 us-gaap_PropertyPlantAndEquipmentGross / us-gaap_PublicUtilityRegulatedOrUnregulatedStatusAxis = cms_EnterprisesOtherMember |  | 26 us-gaap_PropertyPlantAndEquipmentGross / us-gaap_PublicUtilityRegulatedOrUnregulatedStatusAxis = cms_EnterprisesOtherMember |  |
Enterprises Other [Member] | Minimum [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Estimated Depreciable Life in Years, Other | 3 years |  |  |  |
Enterprises Other [Member] | Maximum [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Estimated Depreciable Life in Years, Other | 40 years |  |  |  |
Other [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Other non-utility property | 41 us-gaap_PropertyPlantAndEquipmentOther / us-gaap_PublicUtilityRegulatedOrUnregulatedStatusAxis = us-gaap_OtherCapitalizedPropertyPlantAndEquipmentMember |  | 40 us-gaap_PropertyPlantAndEquipmentOther / us-gaap_PublicUtilityRegulatedOrUnregulatedStatusAxis = us-gaap_OtherCapitalizedPropertyPlantAndEquipmentMember |  |
Other [Member] | Minimum [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Estimated Depreciable Life in Years, Other | 1 year |  |  |  |
Other [Member] | Maximum [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Estimated Depreciable Life in Years, Other | 51 years |  |  |  |
Other [Member] | Consumers Energy Company [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Other non-utility property | 15 us-gaap_PropertyPlantAndEquipmentOther / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_PublicUtilityRegulatedOrUnregulatedStatusAxis = us-gaap_OtherCapitalizedPropertyPlantAndEquipmentMember |  | 15 us-gaap_PropertyPlantAndEquipmentOther / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_PublicUtilityRegulatedOrUnregulatedStatusAxis = us-gaap_OtherCapitalizedPropertyPlantAndEquipmentMember |  |
Other [Member] | Consumers Energy Company [Member] | Minimum [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Estimated Depreciable Life in Years, Other | 8 years |  |  |  |
Other [Member] | Consumers Energy Company [Member] | Maximum [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Estimated Depreciable Life in Years, Other | 51 years |  |  |  |
Base Natural Gas [Member] | Gas Underground Storage Facilities [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment | 26 us-gaap_PublicUtilitiesPropertyPlantAndEquipmentOtherPropertyPlantAndEquipment / cms_BaseNaturalGasAxis = cms_BaseNaturalGasMember / us-gaap_PublicUtilityAxis = cms_GasUndergroundStorageFacilitiesMember |  | 26 us-gaap_PublicUtilitiesPropertyPlantAndEquipmentOtherPropertyPlantAndEquipment / cms_BaseNaturalGasAxis = cms_BaseNaturalGasMember / us-gaap_PublicUtilityAxis = cms_GasUndergroundStorageFacilitiesMember |  |
Base Natural Gas [Member] | Gas Underground Storage Facilities [Member] | Consumers Energy Company [Member] |  |  |  |  |
Public Utility, Property, Plant and Equipment [Line Items] |  |  |  |  |
Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment | $ 26 us-gaap_PublicUtilitiesPropertyPlantAndEquipmentOtherPropertyPlantAndEquipment / cms_BaseNaturalGasAxis = cms_BaseNaturalGasMember / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_PublicUtilityAxis = cms_GasUndergroundStorageFacilitiesMember |  | $ 26 us-gaap_PublicUtilitiesPropertyPlantAndEquipmentOtherPropertyPlantAndEquipment / cms_BaseNaturalGasAxis = cms_BaseNaturalGasMember / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_PublicUtilityAxis = cms_GasUndergroundStorageFacilitiesMember |  |
[1] | For the year ended December 31, 2014, utility plant additions were $1.6 billion and utility plant retirements were $126 million. For the year ended December 31, 2013, utility plant additions were $1.3 billion and utility plant retirements were $156 million.
[2] | Underground storage includes base natural gas of $26 million at December 31, 2014 and 2013. Base natural gas is not subject to depreciation.

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- Definition Current year acquisitions of long-lived assets used in the normal conduct of business and not intended for resale. Examples include land, buildings, machinery and equipment, certain intangible assets, and other types of furniture and equipment including, but not limited to, office equipment, furniture and fixtures, and computer equipment and software. + References No definition available. + Details
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- Definition Current year divestiture of long-lived assets used in the normal conduct of business and not intended for resale. Examples include land, buildings, machinery and equipment, certain intangible assets, and other types of furniture and equipment including, but not limited to, office equipment, furniture and fixtures, and computer equipment and software. + References No definition available. + Details
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- Definition Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.14) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 14 -Article 5 + Details
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