XML 170 R58.htm IDEA: XBRL DOCUMENT
v3.19.3.a.u2

Regulatory Matters (Schedule Of The Components Of PSCR And GCR Over/(Under) Recoveries) (Details) - USD ($) $ in Millions | Dec. 31, 2019 | Dec. 31, 2018
--- | --- | ---
Public Utilities, General Disclosures [Line Items] |  |
Accrued gas revenue | $ 0 | $ 16
Accrued rate refunds | 35 | 4
Consumers Energy Company |  |
Public Utilities, General Disclosures [Line Items] |  |
Accrued gas revenue | 0 | 16
Accrued rate refunds | 35 | 4
Consumers Energy Company | GCR overrecoveries/underrecoveries |  |
Public Utilities, General Disclosures [Line Items] |  |
Accrued gas revenue | 0 | 16
Accrued rate refunds | 2 | 0
Consumers Energy Company | PSCR overrecoveries |  |
Public Utilities, General Disclosures [Line Items] |  |
Accrued rate refunds | $ 33 | $ 4

X
- Definition Current liabilities that represent obligations to make refunds to customers for fuel costs. + References No definition available. + Details
Name: | cms_AccruedRateRefunds
Namespace Prefix: | cms_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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_PublicUtilitiesGeneralDisclosuresLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Discloses the amount of unrecovered costs for purchased gas. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 340 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6499975&loc=d3e44250-110382 + Details
Name: | us-gaap_UnrecoveredCostsForPurchasedGasAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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

X
- Details
Name: | us-gaap_PublicUtilitiesRegulatoryProceedingAxis=cms_GasCostRecoveryMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PublicUtilitiesRegulatoryProceedingAxis=cms_PowerSupplyCostRecoveryMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |