XML 147 R126.htm IDEA: XBRL DOCUMENT
v3.21.1

16. INVESTMENTS (Details 5) | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019
Amazonia [member] |  |  |
Disclosure of detailed information about investment property [line items] |  |  |
Direct interest % | [1] | 74.50% | 74.50%
Indirect interest % | [1] | 5.76% | 5.76%
Lightger [member] |  |  |
Disclosure of detailed information about investment property [line items] |  |  |
Direct interest % | [1] | 49.00% | 49.00%
Indirect interest % | [1] | 11.52% | 11.52%
Guanhaes [member] |  |  |
Disclosure of detailed information about investment property [line items] |  |  |
Direct interest % | [1] | 49.00% | 49.00%
Indirect interest % | [1] | 11.52% | 11.52%
Axxion [member] |  |  |
Disclosure of detailed information about investment property [line items] |  |  |
Direct interest % | [1] | 49.00% | 49.00%
Indirect interest % | [1] | 11.52% | 11.52%
UHE Itaocara [member] |  |  |
Disclosure of detailed information about investment property [line items] |  |  |
Direct interest % | [1] | 49.00% | 49.00%
Indirect interest % | [1] | 11.52% | 11.52%
[1] | After selling the shares held in Light, on January 22, 2021, the Company no longer holds the indirect interest above.

X
- Definition The percentage represents of direct stake. + References No definition available. + Details
Name: | cig_PercentageOfDirectStake
Namespace Prefix: | cig_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition The percentage represents of indirect stake. + References No definition available. + Details
Name: | cig_PercentageOfIndirectStake
Namespace Prefix: | cig_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

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_DisclosureOfInvestmentPropertyLineItems
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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

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

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

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

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