XML 114 R93.htm IDEA: XBRL DOCUMENT
v3.21.1

7. MARKETABLE SECURITIES (Details Narrative) | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Debentures [member] | Bottom Of Range [member] |  |  |
Disclosure of Investment Securities [line items] |  |  |
Investment rate remunerated at percentage of rate for interbank deposits | 1.00% | 108.25% | 104.25%
Debentures [member] | Top of Range [member] |  |  |
Disclosure of Investment Securities [line items] |  |  |
Investment rate remunerated at percentage of rate for interbank deposits | 109.00% | 113.00% | 151.00%
Financial Notes Banks [member] | Bottom Of Range [member] |  |  |
Disclosure of Investment Securities [line items] |  |  |
Investment rate remunerated at percentage of rate for interbank deposits | 99.50% | 101.95% | 102.00%
Financial Notes Banks [member] | Top of Range [member] |  |  |
Disclosure of Investment Securities [line items] |  |  |
Investment rate remunerated at percentage of rate for interbank deposits | 130.00% | 113.00% | 111.25%

X
- Definition Disclosure of investment securities. + References No definition available. + Details
Name: | cig_DisclosureOfInvestmentSecuritiesLineItems
Namespace Prefix: | cig_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Investment securities rate remunerated at percentage of rate for interbank deposits. + References No definition available. + Details
Name: | cig_InvestmentSecuritiesRateRemuneratedAtPercentageOfRateForInterbankDeposits
Namespace Prefix: | cig_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | ifrs-full_TypesOfInterestRatesAxis=cig_DebenturesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_RangeAxis=ifrs-full_BottomOfRangeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_RangeAxis=ifrs-full_TopOfRangeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ifrs-full_TypesOfInterestRatesAxis=cig_FinancialNotesBanksMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |