XML 125 R94.htm IDEA: XBRL DOCUMENT
v3.3.1.900

Retirement Benefits (Schedule Of Benefit Obligations In Excess Of Fair Value Of Plan Assets) (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013
Pension Plan [Member] |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Benefit obligation at beginning of period |  | $ 2,547 | $ 2,073 |
Service cost |  | 49 | 41 |
Interest cost |  | 102 | 99 |
Plan amendments |  | 13 |  |
Actuarial (gain) loss |  | (153) | 458 |
Benefits paid |  | (155) | (124) |
Benefit obligation at end of period |  | 2,403 | 2,547 | $ 2,073
Plan assets at fair value at beginning of period |  | 1,979 | 1,964 |
Actual return on plan assets |  | (36) | 139 |
Company contributions |  | 225 |  |
Actual benefits paid |  | (155) | (124) |
Plan assets at fair value at end of period |  | 2,013 | 1,979 | 1,964
Funded status | [1],[2] | (390) | (568) |
Pension Plan [Member] | Consumers Energy Company [Member] |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Funded status |  | (368) | (532) |
DB SERP [Member] |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Benefit obligation at beginning of period |  | 156 | 132 |
Service cost |  | 1 | 1 |
Interest cost |  | 6 | 6 |
Actuarial (gain) loss |  | (5) | 24 |
Benefits paid |  | (8) | (7) |
Benefit obligation at end of period |  | 150 | 156 | 132
Company contributions |  | 8 | 7 |
Actual benefits paid |  | (8) | (7) |
Funded status |  | (150) | (156) |
DB SERP [Member] | Consumers Energy Company [Member] |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Benefit obligation at beginning of period |  | 111 | 93 |
Service cost |  | 1 | 1 |
Interest cost |  | 4 | 4 |
Actuarial (gain) loss |  | (5) | 17 |
Benefits paid |  | (5) | (4) |
Benefit obligation at end of period |  | 106 | 111 | 93
Company contributions |  | 5 | 4 |
Actual benefits paid |  | (5) | (4) |
Funded status |  | (106) | (111) |
OPEB [Member] |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Benefit obligation at beginning of period |  | 1,378 | 1,123 |
Service cost |  | 25 | 20 | 29
Interest cost |  | 58 | 56 | 65
Plan amendments |  | (25) |  |
Actuarial (gain) loss |  | (152) | 230 |
Benefits paid | [3] | (57) | (51) |
Benefit obligation at end of period |  | 1,227 | 1,378 | 1,123
Plan assets at fair value at beginning of period |  | 1,265 | 1,218 |
Actual return on plan assets |  | (29) | 72 |
Company contributions |  | 29 | 25 |
Actual benefits paid | [3] | (57) | (50) |
Plan assets at fair value at end of period |  | 1,208 | 1,265 | 1,218
Funded status |  | (19) | (113) |
Defined Benefit Plan, Gross Prescription Drug Subsidy Receipts Received |  |  | 4 | 5
OPEB [Member] | Maximum [Member] |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Defined Benefit Plan, Gross Prescription Drug Subsidy Receipts Received |  | 1 |  |
OPEB [Member] | Consumers Energy Company [Member] |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Benefit obligation at beginning of period |  | 1,336 | 1,088 |
Service cost |  | 25 | 20 | 28
Interest cost |  | 56 | 54 | 63
Plan amendments |  | (24) |  |
Actuarial (gain) loss |  | (150) | 223 |
Benefits paid | [3] | (55) | (49) |
Benefit obligation at end of period |  | 1,188 | 1,336 | 1,088
Plan assets at fair value at beginning of period |  | 1,186 | 1,141 |
Actual return on plan assets |  | (27) | 68 |
Company contributions |  | 29 | 25 |
Actual benefits paid | [3] | (55) | (48) |
Plan assets at fair value at end of period |  | 1,133 | 1,186 | 1,141
Funded status |  | (55) | (150) |
Defined Benefit Plan, Gross Prescription Drug Subsidy Receipts Received |  |  | $ 4 | $ 4
OPEB [Member] | Consumers Energy Company [Member] | Maximum [Member] |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Defined Benefit Plan, Gross Prescription Drug Subsidy Receipts Received |  | $ 1 |  |
[1] | At December 31, 2015, $368 million of the total funded status of the DB Pension Plan was attributable to Consumers, based on an allocation of expenses. At December 31, 2014, $532 million of the total funded status of the DB Pension Plan was attributable to Consumers, based on an allocation of expenses.
[2] | The actuarial loss for 2014 was primarily the result of lowering the discount rates used in calculating the plans' obligations and using the RP-2014 mortality table during the annual measurement of benefit obligations.
[3] | CMS Energy received less than $1 million in 2015, $4 million in 2014, and $5 million in 2013 for the Medicare Part D subsidies. Consumers received less than $1 million in 2015 and $4 million in each of 2014 and 2013 for the Medicare Part D subsidies. The Medicare Part D subsidy payments are used to pay OPEB Plan benefits.

X
- Definition Defined Benfefit Plan Benefits Paid Plus Cash Payments + References No definition available. + Details
Name: | cms_DefinedBenfefitPlanBenefitsPaidPlusCashPayments
Namespace Prefix: | cms_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The difference between fair value of plan assets at the end of the period and the fair value at the beginning of the period, adjusted for contributions and payments of benefits during the period, and after adjusting for taxes and other expenses, as applicable. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Actual Return on Plan Assets (Component of Net Periodic Postretirement Benefit Cost) -URI http://asc.fasb.org/extlink&oid=6504192 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b)(1) -URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Actual Return on Plan Assets (Component of Net Periodic Pension Cost) -URI http://asc.fasb.org/extlink&oid=6504226 + Details
Name: | us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of gain (loss) related to change in benefit obligation resulting from changes in actuarial assumptions, for example, but not limited to, interest, mortality, employee turnover, salary, and temporary deviation from the substantive plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Gain or Loss -URI http://asc.fasb.org/extlink&oid=49168827 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a)(4) -URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanActuarialGainLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition 1) For defined benefit pension plans, the benefit obligation is the projected benefit obligation, which is the actuarial present value as of a date of all benefits attributed by the pension benefit formula to employee service rendered prior to that date. 2) For other postretirement defined benefit plans, the benefit obligation is the accumulated postretirement benefit obligation, which is the actuarial present value of benefits attributed to employee service rendered to a particular date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Projected Benefit Obligation -URI http://asc.fasb.org/extlink&oid=6522206 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Accumulated Postretirement Benefit Obligation -URI http://asc.fasb.org/extlink&oid=6503904 + Details
Name: | us-gaap_DefinedBenefitPlanBenefitObligation
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The amount of payments made for which participants are entitled under a pension plan, including pension benefits, death benefits, and benefits due on termination of employment. Also includes payments made under a postretirement benefit plan, including prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services. This item represents a periodic decrease to the plan obligations and a decrease to plan assets. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 60 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=6414203&loc=d3e39716-114964 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Benefits -URI http://asc.fasb.org/extlink&oid=49170737 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a)(6) -URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Postretirement Benefits -URI http://asc.fasb.org/extlink&oid=6521376 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b)(5) -URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanBenefitsPaid
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The increase in the fair value of plan assets from contributions made by the employer. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b)(3) -URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanContributionsByEmployer
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition 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. + References No definition available. + Details
Name: | us-gaap_DefinedBenefitPlanDisclosureLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Assets, usually stocks, bonds, and other investments, that have been segregated and restricted (usually in a trust) to provide benefits, at their fair value as of the measurement date. Plan assets include amounts contributed by the employer (and by employees for a contributory plan) and amounts earned from investing the contributions, less benefits paid. If a plan has liabilities other than for benefits, those non-benefit obligations may be considered as reductions of plan assets. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 30 -Section 35 -Paragraph 50 -URI http://asc.fasb.org/extlink&oid=49178875&loc=d3e12355-114930 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The funded status is measured as the difference between the fair value of plan assets and the benefit obligation. Will normally be the same as the net Defined Benefit Plan, Amounts Recognized in Balance Sheet, Total. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=21915240&loc=d3e1703-114919 + Details
Name: | us-gaap_DefinedBenefitPlanFundedStatusOfPlan
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of the period's gross receipts received from the prescription drug subsidy, which is to be used in the roll forward of the accumulated postretirement benefit obligation of an applicable postretirement benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 60 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=6414203&loc=d3e39716-114964 + Details
Name: | us-gaap_DefinedBenefitPlanGrossPrescriptionDrugSubsidyReceiptsReceived
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The increase in a defined benefit pension plan's projected benefit obligation or a defined benefit postretirement plan's accumulated postretirement benefit obligation due to the passage of time. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h)(2) -URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanInterestCost
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The amount of increase or decrease due to a change in the terms of an existing plan or the initiation of a new plan. A plan amendment may increase or decrease benefits, including those attributed to years of service already rendered. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Plan Amendment -URI http://asc.fasb.org/extlink&oid=49173939 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a)(7) -URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanPlanAmendments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The actuarial present value of benefits attributed by the pension benefit formula to services rendered by employees during the period. The portion of the expected postretirement benefit obligation attributed to employee service during the period. The service cost component is a portion of the benefit obligation and is unaffected by the funded status of the plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Service Cost (Component of Net Periodic Pension Cost) -URI http://asc.fasb.org/extlink&oid=6525008 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h)(1) -URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanServiceCost
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis=us-gaap_PensionPlansDefinedBenefitMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

X
- Details
Name: | us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis=us-gaap_SupplementalEmployeeRetirementPlanDefinedBenefitMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis=us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |