XML 133 R112.htm IDEA: XBRL DOCUMENT
v3.21.1

14. CONCESSION FINANCIAL AND SECTOR ASSETS AND LIABILITIES (Details 2) R$ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2020 BRL (R$) MW | Dec. 31, 2019 BRL (R$) | Dec. 31, 2018 BRL (R$)
Disclosure Of Financial Assets and Liabilities Of The Concession [line items] |  |  |
Installed capacity (MW) | MW | 360,170 |  |
Net balance of assets based on historical cost | R$ 204 |  |
Net balance of assets based on fair value (replacement cost) | 816 | R$ 816 |
Amounts received | R$ (265) | R$ (250) | R$ (250)
Cemig PCH marmelos [member] |  |  |
Disclosure Of Financial Assets and Liabilities Of The Concession [line items] |  |  |
Concession expiration date | 2015-07 |  |
Installed capacity (MW) | MW | 4.00 |  |
Net balance of assets based on historical cost | R$ 1 |  |
Net balance of assets based on fair value (replacement cost) | R$ 4 |  |
Cemig PCH paciencia [member] |  |  |
Disclosure Of Financial Assets and Liabilities Of The Concession [line items] |  |  |
Concession expiration date | 2015-07 |  |
Installed capacity (MW) | MW | 4.08 |  |
Net balance of assets based on historical cost | R$ 1 |  |
Net balance of assets based on fair value (replacement cost) | R$ 4 |  |
Cemig PCH cajuru [member] |  |  |
Disclosure Of Financial Assets and Liabilities Of The Concession [line items] |  |  |
Concession expiration date | 2015-07 |  |
Installed capacity (MW) | MW | 7.20 |  |
Net balance of assets based on historical cost | R$ 4 |  |
Net balance of assets based on fair value (replacement cost) | R$ 4 |  |
Cemig PCH martins [member] |  |  |
Disclosure Of Financial Assets and Liabilities Of The Concession [line items] |  |  |
Concession expiration date | 2015-07 |  |
Installed capacity (MW) | MW | 7.70 |  |
Net balance of assets based on historical cost | R$ 2 |  |
Net balance of assets based on fair value (replacement cost) | R$ 4 |  |
Cemig PCH joasal [member] |  |  |
Disclosure Of Financial Assets and Liabilities Of The Concession [line items] |  |  |
Concession expiration date | 2015-07 |  |
Installed capacity (MW) | MW | 8.40 |  |
Net balance of assets based on historical cost | R$ 1 |  |
Net balance of assets based on fair value (replacement cost) | R$ 8 |  |
Cemig PCH tronqueiras [member] |  |  |
Disclosure Of Financial Assets and Liabilities Of The Concession [line items] |  |  |
Concession expiration date | 2015-07 |  |
Installed capacity (MW) | MW | 8.50 |  |
Net balance of assets based on historical cost | R$ 2 |  |
Net balance of assets based on fair value (replacement cost) | R$ 12 |  |
Cemig PCH dona rita [member] |  |  |
Disclosure Of Financial Assets and Liabilities Of The Concession [line items] |  |  |
Concession expiration date | 2013-09 |  |
Installed capacity (MW) | MW | 2.41 |  |
Net balance of assets based on historical cost | R$ 1 |  |
Net balance of assets based on fair value (replacement cost) | R$ 1 |  |
Cemig PCH peti [member] |  |  |
Disclosure Of Financial Assets and Liabilities Of The Concession [line items] |  |  |
Concession expiration date | 2015-07 |  |
Installed capacity (MW) | MW | 9.40 |  |
Net balance of assets based on historical cost | R$ 1 |  |
Net balance of assets based on fair value (replacement cost) | R$ 8 |  |
Cemig PCH gafanhoto [member] |  |  |
Disclosure Of Financial Assets and Liabilities Of The Concession [line items] |  |  |
Concession expiration date | 2015-07 |  |
Installed capacity (MW) | MW | 14.00 |  |
Net balance of assets based on historical cost | R$ 1 |  |
Net balance of assets based on fair value (replacement cost) | R$ 10 |  |
Cemig PCH piau [member] |  |  |
Disclosure Of Financial Assets and Liabilities Of The Concession [line items] |  |  |
Concession expiration date | 2015-07 |  |
Installed capacity (MW) | MW | 18.01 |  |
Net balance of assets based on historical cost | R$ 2 |  |
Net balance of assets based on fair value (replacement cost) | R$ 9 |  |
Usina hidreletrica sao simao [member] |  |  |
Disclosure Of Financial Assets and Liabilities Of The Concession [line items] |  |  |
Concession expiration date | 2015-01 |  |
Installed capacity (MW) | MW | 1.710 |  |
Net balance of assets based on historical cost | R$ 2 |  |
Net balance of assets based on fair value (replacement cost) | R$ 3 |  |
Usina hidreletrica jaguara [member] |  |  |
Disclosure Of Financial Assets and Liabilities Of The Concession [line items] |  |  |
Concession expiration date | 2013-08 |  |
Installed capacity (MW) | MW | 424.00 |  |
Net balance of assets based on historical cost | R$ 40 |  |
Net balance of assets based on fair value (replacement cost) | R$ 174 |  |
Usina hidreletrica miranda [member] |  |  |
Disclosure Of Financial Assets and Liabilities Of The Concession [line items] |  |  |
Concession expiration date | 2016-12 |  |
Installed capacity (MW) | MW | 408.00 |  |
Net balance of assets based on historical cost | R$ 27 |  |
Net balance of assets based on fair value (replacement cost) | R$ 23 |  |
Usina hidreletrica volta grande [member] |  |  |
Disclosure Of Financial Assets and Liabilities Of The Concession [line items] |  |  |
Concession expiration date | 2017-02 |  |
Installed capacity (MW) | MW | 380.00 |  |
Net balance of assets based on historical cost | R$ 26 |  |
Net balance of assets based on fair value (replacement cost) | R$ 70 |  |
Usina hidreletrica camargos [member] |  |  |
Disclosure Of Financial Assets and Liabilities Of The Concession [line items] |  |  |
Concession expiration date | 2015-07 |  |
Installed capacity (MW) | MW | 46.00 |  |
Net balance of assets based on historical cost | R$ 8 |  |
Net balance of assets based on fair value (replacement cost) | R$ 23 |  |
Usina hidreletrica itutinga [member] |  |  |
Disclosure Of Financial Assets and Liabilities Of The Concession [line items] |  |  |
Concession expiration date | 2015-07 |  |
Installed capacity (MW) | MW | 52.00 |  |
Net balance of assets based on historical cost | R$ 3 |  |
Net balance of assets based on fair value (replacement cost) | R$ 7 |  |
Usina hidreletrica salto grande [member] |  |  |
Disclosure Of Financial Assets and Liabilities Of The Concession [line items] |  |  |
Concession expiration date | 2015-07 |  |
Installed capacity (MW) | MW | 102.00 |  |
Net balance of assets based on historical cost | R$ 11 |  |
Net balance of assets based on fair value (replacement cost) | R$ 39 |  |
Usina hidreletrica tress marias [member] |  |  |
Disclosure Of Financial Assets and Liabilities Of The Concession [line items] |  |  |
Concession expiration date | 2015-07 |  |
Installed capacity (MW) | MW | 396.00 |  |
Net balance of assets based on historical cost | R$ 71 |  |
Net balance of assets based on fair value (replacement cost) | R$ 413 |  |

X
- Definition Concession expiration date. + References No definition available. + Details
Name: | cig_ConcessionExpirationDate
Namespace Prefix: | cig_
Data Type: | xbrli:gYearMonthItemType
Balance Type: | na
Period Type: | duration

X
- Definition Disclosure Of Financial Assets and Liabilities Of The Concession [line items] + References No definition available. + Details
Name: | cig_DisclosureOfFinancialAssetsAndLiabilitiesOfTheConcessionLineItems
Namespace Prefix: | cig_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Installed capacity. + References No definition available. + Details
Name: | cig_InstalledCapacity
Namespace Prefix: | cig_
Data Type: | num:powerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Net balance of assets deemed cost. + References No definition available. + Details
Name: | cig_NetBalanceOfAssetsDeemedCost
Namespace Prefix: | cig_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Net Balance Of Assets Historic Cost + References No definition available. + Details
Name: | cig_NetBalanceOfAssetsHistoricCost
Namespace Prefix: | cig_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The amount of consideration paid or received in respect of both obtaining and losing control of subsidiaries or other businesses. [Refer: Subsidiaries [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 7 -IssueDate 2020-01-01 -Paragraph 40 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=7&code=ifrs-tx-2020-en-r&anchor=para_40_a&doctype=Standard -URIDate 2020-01-01 + Details
Name: | ifrs-full_ConsiderationPaidReceived
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | ifrs-full_PropertyPlantAndEquipmentByOperatingLeaseStatusAxis=cig_CemigPCHMarmelosMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_PropertyPlantAndEquipmentByOperatingLeaseStatusAxis=cig_CemigPCHPacienciaMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_PropertyPlantAndEquipmentByOperatingLeaseStatusAxis=cig_CemigPCHCajuruMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_PropertyPlantAndEquipmentByOperatingLeaseStatusAxis=cig_CemigPCHMartinsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_PropertyPlantAndEquipmentByOperatingLeaseStatusAxis=cig_CemigPCHJoasalMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_PropertyPlantAndEquipmentByOperatingLeaseStatusAxis=cig_CemigPCHTronqueirasMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_PropertyPlantAndEquipmentByOperatingLeaseStatusAxis=cig_CemigPCHDonaRitaMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_PropertyPlantAndEquipmentByOperatingLeaseStatusAxis=cig_CemigPCHPetiMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_PropertyPlantAndEquipmentByOperatingLeaseStatusAxis=cig_CemigPCHGafanhotoMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_PropertyPlantAndEquipmentByOperatingLeaseStatusAxis=cig_CemigPCHPiauMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_PropertyPlantAndEquipmentByOperatingLeaseStatusAxis=cig_UsinaHidreletricaSaoSimaoMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_PropertyPlantAndEquipmentByOperatingLeaseStatusAxis=cig_UsinaHidreletricaJaguaraMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_PropertyPlantAndEquipmentByOperatingLeaseStatusAxis=cig_UsinaHidreletricaMirandaMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_PropertyPlantAndEquipmentByOperatingLeaseStatusAxis=cig_UsinaHidreletricaVoltaGrandeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_PropertyPlantAndEquipmentByOperatingLeaseStatusAxis=cig_UsinaHidreletricaCamargosMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_PropertyPlantAndEquipmentByOperatingLeaseStatusAxis=cig_UsinaHidreletricaItutingaMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_PropertyPlantAndEquipmentByOperatingLeaseStatusAxis=cig_UsinaHidreletricaSaltoGrandeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_PropertyPlantAndEquipmentByOperatingLeaseStatusAxis=cig_UsinaHidreletricaTresMariasMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |