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

No definition available.

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

No definition available.

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Defined Contribution Plan, Trust Assets, Amount

No definition available.

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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.

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Estimated Time Of Amortization Of Gains (Losses) Life Expectancy

No definition available.

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

No definition available.

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Minimum years of participation required before becoming vested.

No definition available.

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

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

No definition available.

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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.

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No definition available.

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No definition available.

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UnionMembershipByTotalEmployeesPercentage

No definition available.

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

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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.

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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.

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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.

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
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Amount of gain (loss) recognized in net periodic benefit (cost) credit from irrevocable action relieving primary responsibility for benefit obligation and eliminating risk related to obligation and assets used to effect settlement.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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Ultimate trend rate for health care cost for defined benefit postretirement plan.

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

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Amount of cost for defined contribution plan.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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-Topic 715
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-Section 50
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Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan.

No definition available.

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

No definition available.

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Amortization period for the recovery of regulatory asset, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

No definition available.

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Data Type:	na
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Name:	us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis=cms_MultiassetInvestmentsMember
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Data Type:	na
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Data Type:	na
Balance Type:
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Data Type:	na
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Data Type:	na
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Data Type:	na
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Data Type:	na
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Name:	us-gaap_RetirementPlanNameAxis=cms_Plan401KMember
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Data Type:	na
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Data Type:	na
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Data Type:	na
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