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Contingencies And Commitments (Guarantees) (Details) (USD $) In Millions, unless otherwise specified | 12 Months Ended
--- | ---
Dec. 31, 2014 MW | Dec. 31, 2013 | Dec. 31, 2012
Consumers Energy Company [Member] |  |  |  |
Guarantor Obligations [Line Items] |  |  |  |
Expiration Date | Various through August 2029 |  |  |
Maximum obligation | $ 30 us-gaap_GuaranteeObligationsMaximumExposure / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember |  |  |
Carrying Amount | 1 us-gaap_GuaranteeObligationsCurrentCarryingValue / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember |  |  |
Guarantees [Member] |  |  |  |
Guarantor Obligations [Line Items] |  |  |  |
Expiration Date | Various through March 2021 |  |  |
Maximum obligation | 54 us-gaap_GuaranteeObligationsMaximumExposure / us-gaap_GuaranteeObligationsByNatureAxis = us-gaap_GuaranteeTypeOtherMember |  |  |
Indemnity Obligations From Asset Sales And Other Agreements [Member] |  |  |  |
Guarantor Obligations [Line Items] |  |  |  |
Expiration Date | Various through August 2029 |  |  |
Maximum obligation | 150 us-gaap_GuaranteeObligationsMaximumExposure / us-gaap_LossContingenciesByNatureOfContingencyAxis = us-gaap_IndemnificationGuaranteeMember | [1] |  |
Carrying Amount | 7 us-gaap_GuaranteeObligationsCurrentCarryingValue / us-gaap_LossContingenciesByNatureOfContingencyAxis = us-gaap_IndemnificationGuaranteeMember |  |  |
MCV PPA [Member] |  |  |  |
Guarantor Obligations [Line Items] |  |  |  |
Purchase Obligations Total | 3,425 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceSheetAmount / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_McvPpaMember |  |  |
Purchase Obligations Due in Year One | 370 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFirstAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_McvPpaMember |  |  |
Purchase Obligations Due in Year Two | 384 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnSecondAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_McvPpaMember |  |  |
Purchase Obligations Due in Year Three | 312 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnThirdAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_McvPpaMember |  |  |
Purchase Obligations Due in Year Four | 301 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFourthAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_McvPpaMember |  |  |
Purchase Obligations Due in Year Five | 316 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFifthAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_McvPpaMember |  |  |
Purchase Obligations Due After Year Five | 1,742 us-gaap_UnrecordedUnconditionalPurchaseObligationDueAfterFiveYears / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_McvPpaMember |  |  |
MCV PPA [Member] | Consumers Energy Company [Member] |  |  |  |
Guarantor Obligations [Line Items] |  |  |  |
Purchase Obligations Total | 3,425 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceSheetAmount / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_McvPpaMember |  |  |
Purchase Obligations Due in Year One | 370 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFirstAnniversary / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_McvPpaMember |  |  |
Purchase Obligations Due in Year Two | 384 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnSecondAnniversary / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_McvPpaMember |  |  |
Purchase Obligations Due in Year Three | 312 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnThirdAnniversary / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_McvPpaMember |  |  |
Purchase Obligations Due in Year Four | 301 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFourthAnniversary / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_McvPpaMember |  |  |
Purchase Obligations Due in Year Five | 316 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFifthAnniversary / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_McvPpaMember |  |  |
Purchase Obligations Due After Year Five | 1,742 us-gaap_UnrecordedUnconditionalPurchaseObligationDueAfterFiveYears / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_McvPpaMember |  |  |
Term of Unrecorded Unconditional Purchase Obligations | 35 years |  |  |
Unrecorded Unconditional Purchase Obligations, Minimum Quantity Required | 1,240 cms_UnrecordedUnconditionalPurchaseObligationsMinimumQuantityRequired / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_McvPpaMember |  |  |
Unrecorded Unconditional Purchase Obligation Capacity Charge Per Mwh | 10.14 cms_UnrecordedUnconditionalPurchaseObligationCapacityChargePerMwh / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_McvPpaMember |  |  |
Unrecorded Unconditional Purchase Obligation, Annual Contribution to Renewable Resources Program By Counterparty | 5 cms_UnrecordedUnconditionalPurchaseObligationAnnualContributionToRenewableResourcesProgramByCounterparty / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_McvPpaMember |  |  |
Unrecorded Unconditional Purchase Obligation, Contract Extension Period | 5 years |  |  |
Unrecorded Unconditional Purchase Obligation, Purchases | 300 us-gaap_UnrecordedUnconditionalPurchaseObligationPurchases / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_McvPpaMember |  | 278 us-gaap_UnrecordedUnconditionalPurchaseObligationPurchases / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_McvPpaMember | 319 us-gaap_UnrecordedUnconditionalPurchaseObligationPurchases / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_McvPpaMember
Palisades PPA [Member] |  |  |  |
Guarantor Obligations [Line Items] |  |  |  |
Purchase Obligations Total | 2,661 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceSheetAmount / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_PalisadesPpaMember |  |  |
Purchase Obligations Due in Year One | 331 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFirstAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_PalisadesPpaMember |  |  |
Purchase Obligations Due in Year Two | 342 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnSecondAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_PalisadesPpaMember |  |  |
Purchase Obligations Due in Year Three | 352 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnThirdAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_PalisadesPpaMember |  |  |
Purchase Obligations Due in Year Four | 364 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFourthAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_PalisadesPpaMember |  |  |
Purchase Obligations Due in Year Five | 375 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFifthAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_PalisadesPpaMember |  |  |
Purchase Obligations Due After Year Five | 897 us-gaap_UnrecordedUnconditionalPurchaseObligationDueAfterFiveYears / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_PalisadesPpaMember |  |  |
Palisades PPA [Member] | Consumers Energy Company [Member] |  |  |  |
Guarantor Obligations [Line Items] |  |  |  |
Purchase Obligations Total | 2,661 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceSheetAmount / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_PalisadesPpaMember |  |  |
Purchase Obligations Due in Year One | 331 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFirstAnniversary / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_PalisadesPpaMember |  |  |
Purchase Obligations Due in Year Two | 342 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnSecondAnniversary / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_PalisadesPpaMember |  |  |
Purchase Obligations Due in Year Three | 352 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnThirdAnniversary / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_PalisadesPpaMember |  |  |
Purchase Obligations Due in Year Four | 364 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFourthAnniversary / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_PalisadesPpaMember |  |  |
Purchase Obligations Due in Year Five | 375 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFifthAnniversary / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_PalisadesPpaMember |  |  |
Purchase Obligations Due After Year Five | 897 us-gaap_UnrecordedUnconditionalPurchaseObligationDueAfterFiveYears / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_PalisadesPpaMember |  |  |
Unrecorded Unconditional Purchase Obligation, Purchases | 302 us-gaap_UnrecordedUnconditionalPurchaseObligationPurchases / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_PalisadesPpaMember |  | 338 us-gaap_UnrecordedUnconditionalPurchaseObligationPurchases / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_PalisadesPpaMember | 331 us-gaap_UnrecordedUnconditionalPurchaseObligationPurchases / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_PalisadesPpaMember
Unrecorded Unconditional Purchase Obligations, Maximum Quantity | 798 cms_UnrecordedUnconditionalPurchaseObligationsMaximumQuantity / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_PalisadesPpaMember |  |  |
Related Parties PPA [Member] |  |  |  |
Guarantor Obligations [Line Items] |  |  |  |
Purchase Obligations Total | 1,135 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceSheetAmount / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_RelatedPartiesPpaMember |  |  |
Purchase Obligations Due in Year One | 83 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFirstAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_RelatedPartiesPpaMember |  |  |
Purchase Obligations Due in Year Two | 83 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnSecondAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_RelatedPartiesPpaMember |  |  |
Purchase Obligations Due in Year Three | 85 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnThirdAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_RelatedPartiesPpaMember |  |  |
Purchase Obligations Due in Year Four | 85 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFourthAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_RelatedPartiesPpaMember |  |  |
Purchase Obligations Due in Year Five | 88 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFifthAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_RelatedPartiesPpaMember |  |  |
Purchase Obligations Due After Year Five | 711 us-gaap_UnrecordedUnconditionalPurchaseObligationDueAfterFiveYears / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_RelatedPartiesPpaMember |  |  |
Related Parties PPA [Member] | Consumers Energy Company [Member] |  |  |  |
Guarantor Obligations [Line Items] |  |  |  |
Purchase Obligations Total | 1,135 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceSheetAmount / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_RelatedPartiesPpaMember |  |  |
Purchase Obligations Due in Year One | 83 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFirstAnniversary / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_RelatedPartiesPpaMember |  |  |
Purchase Obligations Due in Year Two | 83 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnSecondAnniversary / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_RelatedPartiesPpaMember |  |  |
Purchase Obligations Due in Year Three | 85 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnThirdAnniversary / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_RelatedPartiesPpaMember |  |  |
Purchase Obligations Due in Year Four | 85 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFourthAnniversary / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_RelatedPartiesPpaMember |  |  |
Purchase Obligations Due in Year Five | 88 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFifthAnniversary / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_RelatedPartiesPpaMember |  |  |
Purchase Obligations Due After Year Five | 711 us-gaap_UnrecordedUnconditionalPurchaseObligationDueAfterFiveYears / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_RelatedPartiesPpaMember |  |  |
Other PPA [Member] |  |  |  |
Guarantor Obligations [Line Items] |  |  |  |
Purchase Obligations Total | 3,915 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceSheetAmount / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_OtherPpaMember |  |  |
Purchase Obligations Due in Year One | 254 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFirstAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_OtherPpaMember |  |  |
Purchase Obligations Due in Year Two | 244 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnSecondAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_OtherPpaMember |  |  |
Purchase Obligations Due in Year Three | 245 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnThirdAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_OtherPpaMember |  |  |
Purchase Obligations Due in Year Four | 247 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFourthAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_OtherPpaMember |  |  |
Purchase Obligations Due in Year Five | 224 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFifthAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_OtherPpaMember |  |  |
Purchase Obligations Due After Year Five | 2,701 us-gaap_UnrecordedUnconditionalPurchaseObligationDueAfterFiveYears / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_OtherPpaMember |  |  |
Other PPA [Member] | Consumers Energy Company [Member] |  |  |  |
Guarantor Obligations [Line Items] |  |  |  |
Purchase Obligations Total | 3,915 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceSheetAmount / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_OtherPpaMember |  |  |
Purchase Obligations Due in Year One | 254 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFirstAnniversary / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_OtherPpaMember |  |  |
Purchase Obligations Due in Year Two | 244 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnSecondAnniversary / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_OtherPpaMember |  |  |
Purchase Obligations Due in Year Three | 245 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnThirdAnniversary / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_OtherPpaMember |  |  |
Purchase Obligations Due in Year Four | 247 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFourthAnniversary / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_OtherPpaMember |  |  |
Purchase Obligations Due in Year Five | 224 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFifthAnniversary / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_OtherPpaMember |  |  |
Purchase Obligations Due After Year Five | 2,701 us-gaap_UnrecordedUnconditionalPurchaseObligationDueAfterFiveYears / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_OtherPpaMember |  |  |
Non-Related Parties [Member] | Consumers Energy Company [Member] |  |  |  |
Guarantor Obligations [Line Items] |  |  |  |
Unrecorded Unconditional Purchase Obligation, Purchases | 354 us-gaap_UnrecordedUnconditionalPurchaseObligationPurchases / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_NonRelatedPartiesMember |  | 345 us-gaap_UnrecordedUnconditionalPurchaseObligationPurchases / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_NonRelatedPartiesMember | 314 us-gaap_UnrecordedUnconditionalPurchaseObligationPurchases / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_NonRelatedPartiesMember
Other Purchase Obligations [Member] |  |  |  |
Guarantor Obligations [Line Items] |  |  |  |
Purchase Obligations Total | 1,812 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceSheetAmount / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_OtherPurchaseObligationsMember |  |  |
Purchase Obligations Due in Year One | 755 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFirstAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_OtherPurchaseObligationsMember |  |  |
Purchase Obligations Due in Year Two | 418 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnSecondAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_OtherPurchaseObligationsMember |  |  |
Purchase Obligations Due in Year Three | 330 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnThirdAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_OtherPurchaseObligationsMember |  |  |
Purchase Obligations Due in Year Four | 80 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFourthAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_OtherPurchaseObligationsMember |  |  |
Purchase Obligations Due in Year Five | 76 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFifthAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_OtherPurchaseObligationsMember |  |  |
Purchase Obligations Due After Year Five | 153 us-gaap_UnrecordedUnconditionalPurchaseObligationDueAfterFiveYears / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_OtherPurchaseObligationsMember |  |  |
Other Purchase Obligations [Member] | Consumers Energy Company [Member] |  |  |  |
Guarantor Obligations [Line Items] |  |  |  |
Purchase Obligations Total | 1,546 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceSheetAmount / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_OtherPurchaseObligationsMember |  |  |
Purchase Obligations Due in Year One | 721 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFirstAnniversary / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_OtherPurchaseObligationsMember |  |  |
Purchase Obligations Due in Year Two | 389 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnSecondAnniversary / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_OtherPurchaseObligationsMember |  |  |
Purchase Obligations Due in Year Three | 301 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnThirdAnniversary / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_OtherPurchaseObligationsMember |  |  |
Purchase Obligations Due in Year Four | 51 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFourthAnniversary / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_OtherPurchaseObligationsMember |  |  |
Purchase Obligations Due in Year Five | 47 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFifthAnniversary / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_OtherPurchaseObligationsMember |  |  |
Purchase Obligations Due After Year Five | $ 37 us-gaap_UnrecordedUnconditionalPurchaseObligationDueAfterFiveYears / dei_LegalEntityAxis = cms_ConsumersEnergyCompanyMember / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = cms_OtherPurchaseObligationsMember |  |  |
[1] | The majority of this amount arises from stock and asset sale agreements under which CMS Energy or a subsidiary of CMS Energy, other than Consumers, indemnified the purchaser for losses resulting from various matters, including claims related to tax disputes, claims related to PPAs, and defects in title to the assets or stock sold to the purchaser by CMS Energy subsidiaries. Except for items described elsewhere in this Note, CMS Energy believes the likelihood of material loss to be remote for the indemnity obligations not recorded as liabilities.

X
- Definition Describes the term of the unconditional purchase obligations that are not recorded as a liability on the balance sheet. + References No definition available. + Details
Name: | cms_TermOfUnrecordedUnconditionalPurchaseObligations
Namespace Prefix: | cms_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Annual contribution to be paid by counterparty to a renewable resources program. + References No definition available. + Details
Name: | cms_UnrecordedUnconditionalPurchaseObligationAnnualContributionToRenewableResourcesProgramByCounterparty
Namespace Prefix: | cms_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The price per MWh of available capacity that must be paid, in connection with an unconditional purchase obligation that has not been recognized for financial reporting purposes. + References No definition available. + Details
Name: | cms_UnrecordedUnconditionalPurchaseObligationCapacityChargePerMwh
Namespace Prefix: | cms_
Data Type: | us-types:perUnitItemType
Balance Type: | na
Period Type: | instant

X
- Definition Specifies length of time the contract can be extended at the end of the contract term. + References No definition available. + Details
Name: | cms_UnrecordedUnconditionalPurchaseObligationContractExtensionPeriod
Namespace Prefix: | cms_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Maximum number of power units that may be acquired, in connection with an unconditional purchase obligation that has not been recognized for financial reporting purposes. + References No definition available. + Details
Name: | cms_UnrecordedUnconditionalPurchaseObligationsMaximumQuantity
Namespace Prefix: | cms_
Data Type: | num:powerItemType
Balance Type: | na
Period Type: | duration

X
- Definition The minimum number of units that must be purchased, in connection with unconditional purchase obligations that have not been recognized for financial reporting purposes. + References No definition available. + Details
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- Definition The current carrying amount of the liability for the freestanding or embedded guarantor's obligations under the guarantee or each group of similar guarantees. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 460 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6851643&loc=d3e12069-110248 + Details
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- Definition Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 460 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (b)(1) -URI http://asc.fasb.org/extlink&oid=6851643&loc=d3e12069-110248 + Details
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- Definition Describe the approximate term of the guarantee or each group of similar guarantees. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 460 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6851643&loc=d3e12069-110248 + Details
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- Definition Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing in the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 440 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6394976&loc=d3e25336-109308 + Details
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- Definition Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing in the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 440 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6394976&loc=d3e25336-109308 + Details
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- Definition Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing in the fourth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 440 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6394976&loc=d3e25336-109308 + Details
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- Definition Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing in the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 440 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6394976&loc=d3e25336-109308 + Details
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- Definition Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing in the third fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 440 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6394976&loc=d3e25336-109308 + Details
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- Definition Amount of the unrecorded obligation to transfer funds in the future for fixed or minimum amounts or quantities of goods or services at fixed or minimum prices (for example, as in take-or-pay contracts or throughput contracts). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 440 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6394976&loc=d3e25336-109308 + Details
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- Definition Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing after the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 440 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6394976&loc=d3e25336-109308 + Details
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- Definition The amount purchased during the period under an unrecorded unconditional purchase obligation (for example, under the take-or-pay or throughput contract). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 440 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=6394976&loc=d3e25336-109308 + Details
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