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29. REVENUE (Details 3) - BRL (R$) R$ in Millions |  |  | 12 Months Ended
--- | --- | --- | ---
Dec. 29, 2016 | Jan. 02, 2016 | Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Disclosure of revenue [line items] |  |  |  |  |
Taxes on revenues |  |  | R$ 9,282 | R$ 8,765 | R$ 8,547
Charges to the consumer |  |  | 3,054 | 3,547 | 2,604
Deductions from revenue |  |  | 12,336 | 12,312 | 11,151
Tax rate for customers in the Commercial, services and other activities | 25.00% | 18.00% |  |  |
Research and development [Member] |  |  |  |  |
Disclosure of revenue [line items] |  |  |  |  |
Charges to the consumer |  |  | 41 | 38 | 38
National scientific and technological development fund [Member] |  |  |  |  |
Disclosure of revenue [line items] |  |  |  |  |
Charges to the consumer |  |  | 41 | 38 | 38
Proinfa alternative source [Member] |  |  |  |  |
Disclosure of revenue [line items] |  |  |  |  |
Charges to the consumer |  |  | 52 | 40 | 39
Other Taxes [Member] |  |  |  |  |
Disclosure of revenue [line items] |  |  |  |  |
Taxes on revenues |  |  | 8 | 8 | 8
Pis and pasep tax [Member] |  |  |  |  |
Disclosure of revenue [line items] |  |  |  |  |
Taxes on revenues |  |  | 521 | 553 | 455
ICMS - State VAT [Member] |  |  |  |  |
Disclosure of revenue [line items] |  |  |  |  |
Taxes on revenues |  |  | 6,358 | 5,657 | 5,847
Cofins tax [Member] |  |  |  |  |
Disclosure of revenue [line items] |  |  |  |  |
Taxes on revenues |  |  | 2,395 | 2,547 | 2,237
Energy services inspection fee [Member] |  |  |  |  |
Disclosure of revenue [line items] |  |  |  |  |
Charges to the consumer |  |  | 30 | 26 | 29
Customer charges - the 'Flag Tariff' system [Member] |  |  |  |  |
Disclosure of revenue [line items] |  |  |  |  |
Charges to the consumer |  |  | 294 | 655 | 454
Royalty on water resource [Member] |  |  |  |  |
Disclosure of revenue [line items] |  |  |  |  |
Charges to the consumer |  |  | 43 | 45 | 92
Energy system expansion research [Member] |  |  |  |  |
Disclosure of revenue [line items] |  |  |  |  |
Charges to the consumer |  |  | 20 | 19 | 19
Energy development account [Member] |  |  |  |  |
Disclosure of revenue [line items] |  |  |  |  |
Charges to the consumer |  |  | 2,448 | 2,603 | 1,822
Energy efficiency program [Member] |  |  |  |  |
Disclosure of revenue [line items] |  |  |  |  |
Charges to the consumer |  |  | 69 | 64 | 56
Global reversion reserve [Member] |  |  |  |  |
Disclosure of revenue [line items] |  |  |  |  |
Charges to the consumer |  |  | R$ 16 | R$ 19 | R$ 17

X
- Definition Charges to consumer. + References No definition available. + Details
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Namespace Prefix: | cig_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Charges to customer percentage. + References No definition available. + Details
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Balance Type: | na
Period Type: | duration

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- Definition Deductions from revenues. + References No definition available. + Details
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Period Type: | duration

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- Definition Disclosure of revenue. + References No definition available. + Details
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- Definition Taxes on revenues. + References No definition available. + Details
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Data Type: | xbrli:monetaryItemType
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Period Type: | duration

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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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- Details
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Namespace Prefix: |
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Period Type: |

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- Details
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Balance Type: |
Period Type: |

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- Details
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- 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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- Details
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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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- Details
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- Details
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Namespace Prefix: |
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