XML 83 R76.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Basis of Preparation - Additional Information (Detail) - BRL (R$) R$ in Millions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2017 | Dec. 31, 2016
Disclosure Of Summary Of Significant Accounting Policies [Line Items] |  |
Extension of concession agreement period | 30 years |
Increase (decrease) due to application of IFRS 15 [member] |  |
Disclosure Of Summary Of Significant Accounting Policies [Line Items] |  |
Revenue reclassified amount from adoption of pronouncement | R$ 41 | R$ 48
Residential consumers [member] |  |
Disclosure Of Summary Of Significant Accounting Policies [Line Items] |  |
Provision for doubtful receivables | 90 days |
Commercial consumers [member] |  |
Disclosure Of Summary Of Significant Accounting Policies [Line Items] |  |
Provision for doubtful receivables | 180 days |
Other consumers [member] |  |
Disclosure Of Summary Of Significant Accounting Policies [Line Items] |  |
Provision for doubtful receivables | 360 days |

X
- Definition Additional period of concession agreement. + References No definition available. + Details
Name: | xcmig_AdditionalPeriodOfConcessionAgreement
Namespace Prefix: | xcmig_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Line items representing the disclosure of summary of significant accounting policies. + References No definition available. + Details
Name: | xcmig_DisclosureOfSummaryOfSignificantAccountingPoliciesLineItems
Namespace Prefix: | xcmig_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Noncurrent portion of deferred revenue reclassified. + References No definition available. + Details
Name: | xcmig_NoncurrentPortionOfDeferredRevenueReclassified
Namespace Prefix: | xcmig_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Provisions for doubtful receivables past due period. + References No definition available. + Details
Name: | xcmig_ProvisionsForDoubtfulReceivablesPastDuePeriod
Namespace Prefix: | xcmig_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | ifrs-full_RetrospectiveApplicationAndRetrospectiveRestatementAxis=ifrs-full_IncreaseDecreaseDueToApplicationOfIFRS15Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_TypesOfCustomersAxis=xcmig_ResidentialConsumersMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_TypesOfCustomersAxis=xcmig_CommercialConsumersMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_TypesOfCustomersAxis=xcmig_OtherConsumersMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |