Name:	cms_AmortizedNetGainsAndLossesInExcessOfPboOrMrv
Namespace Prefix:	cms_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

The interest rate used in calculating the service cost of defined benefit plan net periodic benefit cost.

No definition available.

Name:	cms_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostServiceCostDiscountRate
Namespace Prefix:	cms_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Defined Contribution Plan, Employer Matching Contribution, Secondary Percent of Employees' Gross Pay

No definition available.

Name:	cms_DefinedContributionPlanEmployerMatchingContributionSecondaryPercentOfEmployeesGrossPay
Namespace Prefix:	cms_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Defined Contribution Plan, Employer Matching Contribution, Secondary Percent of Match

No definition available.

Name:	cms_DefinedContributionPlanEmployerMatchingContributionSecondaryPercentOfMatch
Namespace Prefix:	cms_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Defined Contribution Plan, Trust Assets, Amount

No definition available.

Name:	cms_DefinedContributionPlanTrustAssetsAmount
Namespace Prefix:	cms_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Estimated time of amortization of gains and losses in excess of ten percent of the greater of the PBO or the MRV over the average remaining service period.

No definition available.

Name:	cms_EstimatedTimeOfAmortizationOfGainsLosses
Namespace Prefix:	cms_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Estimated Time Of Amortization Of Gains (Losses) Life Expectancy

No definition available.

Name:	cms_EstimatedTimeOfAmortizationOfGainsLossesLifeExpectancy
Namespace Prefix:	cms_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

The time period over which new prior service cost/credits will be amortized.

No definition available.

Name:	cms_EstimatedTimeOfPriorServiceCost
Namespace Prefix:	cms_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Minimum years of participation required before becoming vested.

No definition available.

Name:	cms_MinimumYearsOfParticipationBeforeVesting
Namespace Prefix:	cms_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Period for gains or losses to be included in market related value

No definition available.

Name:	cms_PeriodForGainsOrLossesToBeIncludedInMarketRelatedValue
Namespace Prefix:	cms_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Percentage of base pay contributed by the Company to the plan for employees.

No definition available.

Name:	cms_PlanContributionPercentage
Namespace Prefix:	cms_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Participants in the plan include all regular full-time employees covered by the employee health care plan on the day before retirement at age 55 or older with at least ten full years of applicable continuous service. Regular full-time employees who qualify for Pension Plan disability retirement and have 15 years of applicable continuous service may also participate in the plan.

No definition available.

Name:	cms_RetirementAgeRequirement
Namespace Prefix:	cms_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

No definition available.

Name:	cms_RetirementYearsOfService
Namespace Prefix:	cms_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

No definition available.

Name:	cms_RetirementYearsOfServiceWithDisability
Namespace Prefix:	cms_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

UnionMembershipByTotalEmployeesPercentage

No definition available.

Name:	cms_UnionMembershipByTotalEmployeesPercentage
Namespace Prefix:	cms_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Amount of actuarial present value of benefits attributed to employee service rendered, excluding assumptions about future compensation level.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

Name:	us-gaap_DefinedBenefitPlanAccumulatedBenefitObligation
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Amount of contribution received by defined benefit plan from employer which increases plan assets.

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 55
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=118257860&loc=d3e4179-114921

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(iv)(01)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(ii)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 6
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e2709-114920

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (b)(3)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

Name:	us-gaap_DefinedBenefitPlanContributionsByEmployer
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

Name:	us-gaap_DefinedBenefitPlanDisclosureLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Assumed rate, for next fiscal year, based on annual change in cost of health care cost benefits used to measure expected cost of benefits covered by defined benefit postretirement plan. Factors include, but are not limited to, estimate of health care inflation, change in health care utilization or delivery pattern, technological advances, and change in health status of participant. Excludes factors for change in composition of plan population by age and dependency status.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (l)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

Name:	us-gaap_DefinedBenefitPlanHealthCareCostTrendRateAssumedNextFiscalYear
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Amount of increase (decrease) in benefit obligation of defined benefit plan from change in terms of existing plan or initiation of new plan.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (a)(7)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

Name:	us-gaap_DefinedBenefitPlanPlanAmendments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Percentage of target investment allocation to total plan assets. Includes, but is not limited to, percentage on weighted-average basis if more than one plan.

Name:	us-gaap_DefinedBenefitPlanPlanAssetsTargetAllocationPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Ultimate trend rate for health care cost for defined benefit postretirement plan.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (l)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

Name:	us-gaap_DefinedBenefitPlanUltimateHealthCareCostTrendRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Year ultimate health care cost trend rate is expected to be reached, in CCYY format.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (l)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

Name:	us-gaap_DefinedBenefitPlanYearHealthCareCostTrendRateReachesUltimateTrendRate
Namespace Prefix:	us-gaap_
Data Type:	us-types:gYearListItemType
Balance Type:	na
Period Type:	duration

Amount of cost for defined contribution plan.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 70
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=49170846&loc=d3e28014-114942

Name:	us-gaap_DefinedContributionPlanCostRecognized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan.

No definition available.

Name:	us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Percentage employer matches of the employee's percentage contribution matched.

No definition available.

Name:	us-gaap_DefinedContributionPlanEmployerMatchingContributionPercentOfMatch
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

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

Name:	us-gaap_RetirementPlanTypeAxis=us-gaap_PensionPlansDefinedBenefitMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_DefinedBenefitPlanEquitySecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=us-gaap_FixedIncomeFundsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=cms_MultiassetInvestmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_RetirementPlanTypeAxis=us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_RetirementPlanTypeAxis=cms_PensionAndOpebMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_RetirementPlanTypeAxis=us-gaap_DefinedBenefitPostretirementHealthCoverageMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_RetirementPlanTypeAxis=us-gaap_DefinedBenefitPostretirementLifeInsuranceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_RetirementPlanNameAxis=cms_DefinedCompanyContributionPlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_RetirementPlanNameAxis=cms_SupplementalEmployeeRetirementPlanDefinedContributionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_RetirementPlanNameAxis=cms_Plan401KMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_RetirementPlanNameAxis=cms_ActivePensionPlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_RetirementPlanNameAxis=cms_InactivePensionPlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_StatementScenarioAxis=cms_UnderAgeSixtyFiveMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_StatementScenarioAxis=cms_OverAgeSixtyFiveMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: