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18. INTANGIBLE ASSETS (Details 4) | 12 Months Ended
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Dec. 31, 2020 MWh
Emboracao [member] |  |
Disclosure of detailed information about intangible assets [line items] |  |
Physical Guarantee | 500 |
Concession extension (months) | 23 |
Nova Ponte [member] |  |
Disclosure of detailed information about intangible assets [line items] |  |
Physical Guarantee | 270 |
Concession extension (months) | 25 |
Sa Carvalho [member] |  |
Disclosure of detailed information about intangible assets [line items] |  |
Physical Guarantee | 56 |
Concession extension (months) | 22 |
Rosal [member] |  |
Disclosure of detailed information about intangible assets [line items] |  |
Physical Guarantee | 29 |
Concession extension (months) | 46 |
Other [member] |  |
Disclosure of detailed information about intangible assets [line items] |  |
Physical Guarantee | 399 | [1]
Concession extension (months) |  |
[1] | Includes 11 power plants, of which 7 are owned by Cemig GT, 1 is owned by Cemig PCH and 3 are owned by Horizontes. The average concession extension in months varies between 1 and 84 months.

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- Definition Represent information about the concession extension. + References No definition available. + Details
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- Definition Represent physical guarantees. + 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 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: |
Data Type: | na
Balance Type: |
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: |
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: |

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