XML 220 R213.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Insurance - Summary of Amounts Arising From Insurance Contracts (Parenthetical) (Detail) - 12 months ended Dec. 31, 2017 R$ in Millions, $ in Millions | BRL (R$) | USD ($)
--- | --- | ---
Disclosure of types of insurance contracts [line items] |  |
Expense arising from insurance | R$ 0 | $ 0
Cemig Geracao e Transmissao [member] |  |
Disclosure of types of insurance contracts [line items] |  |
Maximum indemnity limit | 231 |
Cemig Distribution [member] |  |
Disclosure of types of insurance contracts [line items] |  |
Maximum indemnity limit | R$ 214 |

X
- Definition Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table. + References No definition available. + Details
Name: | ifrs-full_DisclosureOfTypesOfInsuranceContractsLineItems
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The amount of expense arising from insurance contracts. [Refer: Types of insurance contracts [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 4 -IssueDate 2017-01-01 -Paragraph 37 -Subparagraph b -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=4&date=2017-03-01&anchor=para_37_b&doctype=Standard -URIDate 2017-03-09 + Details
Name: | ifrs-full_ExpenseArisingFromInsuranceContracts
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Maximum indemnity limit of insurance contract. + References No definition available. + Details
Name: | xcmig_MaximumIndemnityLimitOfInsuranceContract
Namespace Prefix: | xcmig_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | ifrs-full_SignificantInvestmentsInSubsidiariesAxis=xcmig_CemigGeracaoETransmissaoMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_SignificantInvestmentsInSubsidiariesAxis=xcmig_CemigDistributionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |