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18. INVESTMENTS (Details Narrative) - BRL (R$) R$ / shares in Units, R$ in Millions |  |  |  | 12 Months Ended |  |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Jan. 23, 2020 | Dec. 27, 2019 | Jan. 28, 2019 | Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2014 | Oct. 25, 2019 | Oct. 15, 2019 | Aug. 07, 2019 | Nov. 30, 2018 | Oct. 31, 2018 | Apr. 23, 2018
Disclosure of detailed information about investment property [line items] |  |  |  |  |  |  |  |  |  |  |  |  |
Provision for losses on investments |  |  |  | R$ 22 |  |  |  |  |  |  |  |  |
Investment Write Downs |  |  |  | 183 |  |  |  |  |  |  |  |  |
Net income (loss) for the year |  |  |  | 3,128 | 1,742 | R$ 1,002 |  |  |  |  |  |  |
Accumulated loss |  |  |  | (2,993) | R$ (1,938) |  |  |  |  |  |  |  |
Negative net working capital |  |  |  | R$ 3,309 |  |  |  |  |  |  |  |  |
Number of shares issued |  |  |  | 1,258,841,654 | 1,458,752,601 | 1,258,841,654 |  |  |  |  |  |  | 199,910,947
Share price |  |  |  | R$ 5.00 |  |  |  |  |  |  |  |  | R$ 5.00
Increase in the share capitaL |  |  |  |  |  |  |  |  |  | R$ 2,600 |  |  |
Consideration paid for the acquisition |  |  |  | R$ 45 |  |  |  |  |  |  |  |  |
Equity deficit |  |  |  | R$ 8,750 | R$ 6,362 | R$ 5,729 |  |  |  |  |  |  |
Parajuru, Volta do Rio and Morgado [member] |  |  |  |  |  |  |  |  |  |  |  |  |
Disclosure of detailed information about investment property [line items] |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage Of Minority Interest |  |  |  | 49.00% |  |  |  |  |  |  |  |  |
Light [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Disclosure of detailed information about investment property [line items] |  |  |  |  |  |  |  |  |  |  |  |  |
Interest acquisition percentage |  |  |  |  |  |  |  |  |  |  | 47.25% |  |
Light SA [member] | Cemig GT [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Disclosure of detailed information about investment property [line items] |  |  |  |  |  |  |  |  |  |  |  |  |
Interest acquisition percentage |  |  |  |  | 49.99% |  |  |  |  |  |  |  |
Renova [Member] | Cemig GT [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Disclosure of detailed information about investment property [line items] |  |  |  |  |  |  |  |  |  |  |  |  |
Advance against future capital increase |  |  |  |  |  |  |  | R$ 5 |  |  |  |  |
Mesa [Member] | Cemig GT [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Disclosure of detailed information about investment property [line items] |  |  |  |  |  |  |  |  |  |  |  |  |
Subscribed capital increases |  |  |  |  |  |  |  |  |  |  |  | R$ 25 |
FIP Melbourne [Member] | Cemig GT [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Disclosure of detailed information about investment property [line items] |  |  |  |  |  |  |  |  |  |  |  |  |
Subscribed capital increases |  |  |  |  |  |  |  |  |  |  |  | R$ 26 |
Eletrobras [Member] | Centroeste [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Disclosure of detailed information about investment property [line items] |  |  |  |  |  |  |  |  |  |  |  |  |
Interest acquisition percentage | 49.00% |  |  |  |  |  |  |  |  |  |  |  |
Percentage of holding by investee | 100.00% |  |  |  |  |  |  |  |  |  |  |  |
Belo Monte Plant Through Amaznia Energia S A A And Alianca Norte [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Disclosure of detailed information about investment property [line items] |  |  |  |  |  |  |  |  |  |  |  |  |
Loss contingencies |  |  |  | R$ 1,962 | R$ 1,643 |  |  |  |  |  |  |  |
Renova Energia SA [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Disclosure of detailed information about investment property [line items] |  |  |  |  |  |  |  |  |  |  |  |  |
Current liabilities in excess of consolidated current assets |  |  |  | 2,907 | 458 |  |  |  |  |  |  |  |
Net income (loss) for the year |  |  |  | 688 | (856) |  |  |  |  |  |  |  |
Accumulated loss |  |  |  | 4,010 | 3,051 |  |  |  |  |  |  |  |
Equity deficit |  |  |  | 1,091 | 76 |  |  |  |  |  |  |  |
Effective assets |  |  |  | 35 |  |  |  |  |  |  |  |  |
Impaired assets |  |  |  | 142 |  |  |  |  |  |  |  |  |
Renova Energia SA [Member] | Preferred Shares [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Disclosure of detailed information about investment property [line items] |  |  |  |  |  |  |  |  |  |  |  |  |
Interest acquisition percentage |  |  |  |  |  |  |  |  | 17.17% |  |  |  |
Number of shares issued |  |  |  |  |  |  |  |  | 98 |  |  |  |
Cemig GT [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Disclosure of detailed information about investment property [line items] |  |  |  |  |  |  |  |  |  |  |  |  |
Investment Write Downs |  |  |  |  |  |  | R$ 678 |  |  |  |  |  |
Madeira Energia SA Mesa and FIP Melbourne [member] |  |  |  |  |  |  |  |  |  |  |  |  |
Disclosure of detailed information about investment property [line items] |  |  |  |  |  |  |  |  |  |  |  |  |
Loss contingencies |  |  |  | 951 | 1,743 |  |  |  |  |  |  |  |
Current liabilities in excess of consolidated current assets |  |  |  | 427 | 663 |  |  |  |  |  |  |  |
Madeira Energia (Santo Antonio plant) [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Disclosure of detailed information about investment property [line items] |  |  |  |  |  |  |  |  |  |  |  |  |
Net income (loss) for the year |  |  |  | R$ (951) | (1,743) | (1,091) |  |  |  |  |  |  |
Nominal WACC discount rate |  |  |  | 9.59% |  |  |  |  |  |  |  |  |
Baguari Energia [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Disclosure of detailed information about investment property [line items] |  |  |  |  |  |  |  |  |  |  |  |  |
Net income (loss) for the year |  |  |  | R$ 32 | R$ 41 | 22 |  |  |  |  |  |  |
Belo Monte Plant Through Amaznia Energia SAA and Aliana Norte [member] |  |  |  |  |  |  |  |  |  |  |  |  |
Disclosure of detailed information about investment property [line items] |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of indirect equity interest |  |  |  |  | 11.69% |  |  |  |  |  |  |  |
TAESA [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Disclosure of detailed information about investment property [line items] |  |  |  |  |  |  |  |  |  |  |  |  |
Net income (loss) for the year |  |  |  |  | R$ 1,071 |  |  |  |  |  |  |  |
Number of unit sold |  |  |  | 34,000,000 |  |  |  |  |  |  |  |  |
Sold price (in dollar per share) |  |  |  | R$ 21.1 |  |  |  |  |  |  |  |  |
Percentage of share capital |  |  |  | 31.54% |  |  |  |  |  |  |  |  |
Percentage of reduced share capital |  |  |  | 21.68% |  |  |  |  |  |  |  |  |
Alianca Norte Energia Participacoes S A [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Disclosure of detailed information about investment property [line items] |  |  |  |  |  |  |  |  |  |  |  |  |
Net income (loss) for the year |  |  |  |  | 94 |  |  |  |  |  |  |  |
Retiro Baixo Energtica SA [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Disclosure of detailed information about investment property [line items] |  |  |  |  |  |  |  |  |  |  |  |  |
Net income (loss) for the year |  |  |  |  | 26 |  |  |  |  |  |  |  |
Renova [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Disclosure of detailed information about investment property [line items] |  |  |  |  |  |  |  |  |  |  |  |  |
Net income (loss) for the year |  |  |  | R$ (1,014) | (856) | (1,140) |  |  |  |  |  |  |
Renova [Member] | Loan Agreements [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Disclosure of detailed information about investment property [line items] |  |  |  |  |  |  |  |  |  |  |  |  |
Loan granted |  | R$ 17 | R$ 20 | 37 |  |  |  |  |  |  |  |  |
Alianca Geracao [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Disclosure of detailed information about investment property [line items] |  |  |  |  |  |  |  |  |  |  |  |  |
Net income (loss) for the year |  |  |  | 229 | 198 | 215 |  |  |  |  |  |  |
Amazonia Energia (Belo Monte plant) [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Disclosure of detailed information about investment property [line items] |  |  |  |  |  |  |  |  |  |  |  |  |
Net income (loss) for the year |  |  |  | R$ 20 | 103 | R$ 1 |  |  |  |  |  |  |
Ativas Data Center [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Disclosure of detailed information about investment property [line items] |  |  |  |  |  |  |  |  |  |  |  |  |
Net income (loss) for the year |  |  |  |  | (21) |  |  |  |  |  |  |  |
Hidreletrica Cachoeirao SA [member] |  |  |  |  |  |  |  |  |  |  |  |  |
Disclosure of detailed information about investment property [line items] |  |  |  |  |  |  |  |  |  |  |  |  |
Net income (loss) for the year |  |  |  |  | 20 |  |  |  |  |  |  |  |
Hidreletrica Pipoca [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Disclosure of detailed information about investment property [line items] |  |  |  |  |  |  |  |  |  |  |  |  |
Net income (loss) for the year |  |  |  |  | 12 |  |  |  |  |  |  |  |
Centroeste [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Disclosure of detailed information about investment property [line items] |  |  |  |  |  |  |  |  |  |  |  |  |
Net income (loss) for the year |  |  |  |  | R$ 10 |  |  |  |  |  |  |  |
Interest acquisition percentage |  |  |  | 51.00% |  |  |  |  |  |  |  |  |
Espra [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Disclosure of detailed information about investment property [line items] |  |  |  |  |  |  |  |  |  |  |  |  |
Estimated due consideration for income tax and social contribution tax |  |  |  | R$ 89 |  |  |  |  |  |  |  |  |

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