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32. RELATED PARTY TRANSACTIONS (Details 3) - Related parties [Member] - Number | 12 Months Ended
--- | ---
Dec. 31, 2019 | Dec. 31, 2018
Disclosure of transactions between related parties [line items] |  |
Number Of Investments |  | 8
Light [Member] |  |
Disclosure of transactions between related parties [line items] |  |
Type |  | Promissory Note
Annual contractual conditions |  | CDI + 3.50%
Maturity |  | Jan. 22, 2019
Number Of Investments |  | 3
ETAU [Member] |  |
Disclosure of transactions between related parties [line items] |  |
Type |  | Debentures
Annual contractual conditions |  | 108.00% of CDI
Maturity |  | Dec. 01, 2019
Number Of Investments |  | 5

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- Definition Description of percentage of investments in related parties. + References No definition available. + Details
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Balance Type: | na
Period Type: | duration

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- Definition Description of type of securities. + References No definition available. + Details
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Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Definition Represent information about the investments maturity date. + References No definition available. + Details
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Namespace Prefix: | cig_
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Balance Type: | na
Period Type: | duration

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- Definition Number of investment units. + References No definition available. + Details
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Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

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- 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
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- Details
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Namespace Prefix: |
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Period Type: |

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- Details
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Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
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Namespace Prefix: |
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Balance Type: |
Period Type: |