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16. INVESTMENTS (Details 1) - BRL (R$) R$ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Disclosure of detailed information about investment property [line items] |  |  |  |  |  |
Beginning balance |  | R$ 704 |  | R$ 745 | R$ 1,108 |
Additions |  |  |  |  | 110 |
Amortization |  | (40) |  | (41) | (74) |
Written off |  |  |  |  | (399) |
Ending balance |  | 664 |  | 704 | 745 |
Retiro baixo [member] |  |  |  |  |  |
Disclosure of detailed information about investment property [line items] |  |  |  |  |  |
Beginning balance |  | 31 |  | 32 | 28 |
Additions |  |  |  |  | 6 |
Amortization |  | (1) |  | (1) | (2) |
Written off |  |  |  |  |  |
Ending balance |  | 30 |  | 31 | 32 |
Central eolica praias de parajuru [member] |  |  |  |  |  |
Disclosure of detailed information about investment property [line items] |  |  |  |  |  |
Beginning balance | [1] |  |  |  | 17 |
Additions | [1] |  |  |  |  |
Amortization | [1] |  |  |  | (2) |
Written off | [1] |  |  |  | (15) |
Ending balance | [1] |  |  |  |  |
Central eolica volta do rio [member] |  |  |  |  |  |
Disclosure of detailed information about investment property [line items] |  |  |  |  |  |
Beginning balance | [1] |  |  |  | 11 |
Additions | [1] |  |  |  |  |
Amortization | [1] |  |  |  | (1) |
Written off |  |  | [2] |  | (10) | [1]
Ending balance | [1] |  |  |  |  |
Central eolica praias de morgado [member] |  |  |  |  |  |
Disclosure of detailed information about investment property [line items] |  |  |  |  |  |
Beginning balance | [1] |  |  |  | 24 |
Additions | [1] |  |  |  |  |
Amortization | [1] |  |  |  | (2) |
Written off | [1] |  |  |  | (22) |
Ending balance | [1] |  |  |  |  |
TAESA [member] |  |  |  |  |  |
Disclosure of detailed information about investment property [line items] |  |  |  |  |  |
Beginning balance |  | 171 |  | 180 | 189 |
Additions |  |  |  |  |  |
Amortization |  | (8) |  | (9) | (9) |
Written off |  |  |  |  |  |
Ending balance |  | 163 |  | 171 | 180 |
Madeira energia (santo antonio plant) [member] |  |  |  |  |  |
Disclosure of detailed information about investment property [line items] |  |  |  |  |  |
Beginning balance |  | 17 |  | 18 | 151 |
Additions |  |  |  |  |  |
Amortization |  | (1) |  | (1) | (6) |
Written off |  |  |  |  | (127) |
Ending balance |  | 16 |  | 17 | 18 |
Lightger [member] |  |  |  |  |  |
Disclosure of detailed information about investment property [line items] |  |  |  |  |  |
Beginning balance |  | 81 |  | 84 |  |
Additions |  |  |  |  | 84 |
Amortization |  | (3) |  | (3) |  |
Written off |  |  |  |  |  |
Ending balance |  | 78 |  | 81 | 84 |
Light [member] |  |  |  |  |  |
Disclosure of detailed information about investment property [line items] |  |  |  |  |  |
Beginning balance |  |  |  |  | 186 |
Additions |  |  |  |  |  |
Amortization |  |  |  |  | (20) |
Written off |  |  |  |  | (166) |
Ending balance |  |  |  |  |  |
Alianca geracao [member] |  |  |  |  |  |
Disclosure of detailed information about investment property [line items] |  |  |  |  |  |
Beginning balance |  | 353 |  | 378 | 403 |
Additions |  |  |  |  |  |
Amortization |  | (25) |  | (25) | (25) |
Written off |  |  |  |  |  |
Ending balance |  | 328 |  | 353 | 378 |
Alianca norte (belo monte plant) [member] |  |  |  |  |  |
Disclosure of detailed information about investment property [line items] |  |  |  |  |  |
Beginning balance |  | 51 |  | 53 | 55 |
Additions |  |  |  |  |  |
Amortization |  | (2) |  | (2) | (2) |
Written off |  |  |  |  |  |
Ending balance |  | 49 |  | 51 | 53 |
RME [member] |  |  |  |  |  |
Disclosure of detailed information about investment property [line items] |  |  |  |  |  |
Beginning balance |  |  |  |  | 44 |
Additions |  |  |  |  | 20 |
Amortization |  |  |  |  | (5) |
Written off |  |  |  |  | (59) |
Ending balance |  |  |  |  |  |
[1] | As from 2018 the investees Central Eolica Praias de Parajuru and Central Eolica Volta do Rio are being consolidated
[2] | As from 2018 the investees Central Eolica Praias de Parajuru and Central Eolica Volta do Rio are being consolidated.

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