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18. INVESTMENTS (Details 1) - BRL (R$) R$ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Disclosure of detailed information about investment property [line items] |  |  |  |  |
Beginning balance |  | R$ 745 |  | R$ 1,108 | R$ 1,325
Additions |  |  |  | 110 |
Amortization |  | (41) |  | (74) | (84)
Written off |  |  |  | (399) | (133)
Ending balance |  | 704 |  | 745 | 1,108
TAESA [Member] |  |  |  |  |
Disclosure of detailed information about investment property [line items] |  |  |  |  |
Beginning balance |  | 180 |  | 189 | 288
Additions |  |  |  |  |
Amortization |  | (9) |  | (9) | (13)
Written off |  |  |  |  | (86)
Ending balance |  | 171 |  | 180 | 189
Retiro Baixo [Member] |  |  |  |  |
Disclosure of detailed information about investment property [line items] |  |  |  |  |
Beginning balance |  | 32 |  | 28 | 29
Additions |  |  |  | 6 |
Amortization |  | (1) |  | (2) | (1)
Written off |  |  |  |  |
Ending balance |  | 31 |  | 32 | 28
Central Eolica Praias De Parajuru [Member] |  |  |  |  |
Disclosure of detailed information about investment property [line items] |  |  |  |  |
Beginning balance | [1] |  |  | 17 | 19
Additions | [1] |  |  |  |
Amortization | [1] |  | [2] | (2) | (1)
Written off | [1] |  |  | (15) | (1)
Ending balance | [1] |  | [2] |  | 17
Central Eolica Volta do Rio [Member] |  |  |  |  |
Disclosure of detailed information about investment property [line items] |  |  |  |  |
Beginning balance | [3] |  |  | 11 | 14
Additions | [3] |  |  |  |
Amortization | [3] |  |  | (1) | (1)
Written off | [3] |  |  | (10) | (2)
Ending balance | [3] |  |  |  | 11
Central Eolica Praias De Morgado [Member] |  |  |  |  |
Disclosure of detailed information about investment property [line items] |  |  |  |  |
Beginning balance | [3] |  |  | 24 | 27
Additions | [3] |  |  |  |
Amortization | [3] |  |  | (2) | (2)
Written off | [3] |  |  | (22) | (1)
Ending balance | [3] |  |  |  | 24
Madeira Energia (Santo Antonio plant) [Member] |  |  |  |  |
Disclosure of detailed information about investment property [line items] |  |  |  |  |
Beginning balance |  | 18 |  | 151 | 157
Additions |  |  |  |  |
Amortization |  | (1) |  | (6) | (6)
Written off |  |  |  | (127) |
Ending balance |  | 17 |  | 18 | 151
Lightger [Member] |  |  |  |  |
Disclosure of detailed information about investment property [line items] |  |  |  |  |
Beginning balance |  | 84 |  |  |
Additions |  |  |  | 84 |
Amortization |  | (3) |  |  |
Written off |  |  |  |  |
Ending balance |  | 81 |  | 84 |
Light [Member] |  |  |  |  |
Disclosure of detailed information about investment property [line items] |  |  |  |  |
Beginning balance |  |  |  | 186 | 209
Additions |  |  |  |  |
Amortization |  |  |  | (20) | (23)
Written off |  |  |  | (166) |
Ending balance |  |  |  |  | 186
Alianca Geracao [Member] |  |  |  |  |
Disclosure of detailed information about investment property [line items] |  |  |  |  |
Beginning balance |  | 378 |  | 403 | 428
Additions |  |  |  |  |
Amortization |  | (25) |  | (25) | (25)
Written off |  |  |  |  |
Ending balance |  | 353 |  | 378 | 403
Alianca Norte (Belo Monte plant) [Member] |  |  |  |  |
Disclosure of detailed information about investment property [line items] |  |  |  |  |
Beginning balance |  | 53 |  | 55 | 57
Additions |  |  |  |  |
Amortization |  | (2) |  | (2) | (2)
Written off |  |  |  |  |
Ending balance |  | 51 |  | 53 | 55
Lepsa [Member] |  |  |  |  |
Disclosure of detailed information about investment property [line items] |  |  |  |  |
Beginning balance |  |  |  |  | 49
Additions |  |  |  |  |
Amortization |  |  |  |  | (6)
Written off |  |  |  |  | (43)
Ending balance |  |  |  |  |
RME [Member] |  |  |  |  |
Disclosure of detailed information about investment property [line items] |  |  |  |  |
Beginning balance |  |  |  | 44 | 48
Additions |  |  |  | 20 |
Amortization |  |  |  | (5) | (4)
Written off |  |  |  | (59) |
Ending balance |  |  |  |  | R$ 44
[1] | As from 2018 the investees Central Eolica Praias de Parajuru and Central Eolica Volta do Rio are being consolidated
[2] | With the cessation of control of Light, the remaining equity interest in these investees was recognized as an investment in affiliates or jointly- controlled subsidiaries, and measured by the equity method, in accordance with IFRS 10. For more details please see Notes 1 and 34.
[3] | Changes arising from the elimination of crossover holding of the assets between Cemig GT and Energimp that occurred in 2018. As from 2018 the investees Central Eolica Praias de Parajuru and Central Eolica Volta do Rio are being consolidated by Cemig GT.

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