XML 110 R103.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Reimbursement Of Tariff Subsidies - Additional Information (Detail) - BRL (R$) R$ in Millions | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
--- | --- | --- | ---
Disclosure Of Energy Development Account [Line Items] |  |  |
Subsidies revenue recognized | R$ 842 | R$ 792 | R$ 801
Cemig D [member] |  |  |
Disclosure Of Energy Development Account [Line Items] |  |  |
Current subsidy receivable | R$ 73 | R$ 64 |

X
- Definition Current subsidy receivable. + References No definition available. + Details
Name: | xcmig_CurrentSubsidyReceivable
Namespace Prefix: | xcmig_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Disclosure of energy development account . + References No definition available. + Details
Name: | xcmig_DisclosureOfEnergyDevelopmentAccountLineItems
Namespace Prefix: | xcmig_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Subsidies revenue recognized. + References No definition available. + Details
Name: | xcmig_SubsidiesRevenueRecognized
Namespace Prefix: | xcmig_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | ifrs-full_CategoriesOfRelatedPartiesAxis=xcmig_CemigDMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |