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Concession Financial Assets and Liabilities - Summary of Generation Indemnity Receivable (Detail) R$ in Millions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2017 BRL (R$) MW | Dec. 31, 2016 BRL (R$)
Disclosure Of Financial Assets and Liabilities Of The Concession [Line Items] |  |
Installed capacity (MW) | MW | 3,601.70 |
Net balance of assets based on historical cost | R$ 204 |
Net balance of assets based on fair value (replacement cost) | 816 | R$ 547
Monitory adjustment (C) | 317 | R$ 352
Miranda and Sao Simao hydroelectric plants [member] |  |
Disclosure Of Financial Assets and Liabilities Of The Concession [Line Items] |  |
Net balance of assets based on historical cost | 814 |
Net balance of assets based on fair value (replacement cost) | 838 |
Residual value of assets of basis project based on replacement of cost at December 2017 | 813 |
Adjustment | 215 |
Amounts based on MME Order 291 (A)+(B) | 1,028 |
Monitory adjustment (C) | 56 |
Residual value of assets of basis project at 2017 | R$ 1,084 |
Miranda and Sao Simao hydroelectric plants [member] | Miranda hydroelectric plant [member] |  |
Disclosure Of Financial Assets and Liabilities Of The Concession [Line Items] |  |
Concession expiration date | 2016-12 |
Net balance of assets based on historical cost | R$ 751 |
Net balance of assets based on fair value (replacement cost) | 632 |
Residual value of assets of basis project based on replacement of cost at December 2017 | 610 |
Adjustment | 174 |
Amounts based on MME Order 291 (A)+(B) | 784 |
Monitory adjustment (C) | 25 |
Residual value of assets of basis project at 2017 | R$ 809 |
Miranda and Sao Simao hydroelectric plants [member] | Sao simao hydroelectric plant [member] |  |
Disclosure Of Financial Assets and Liabilities Of The Concession [Line Items] |  |
Concession expiration date | 2015-01 |
Net balance of assets based on historical cost | R$ 63 |
Net balance of assets based on fair value (replacement cost) | 206 |
Residual value of assets of basis project based on replacement of cost at December 2017 | 203 |
Adjustment | 41 |
Amounts based on MME Order 291 (A)+(B) | 244 |
Monitory adjustment (C) | 31 |
Residual value of assets of basis project at 2017 | R$ 275 |
Tres Marias Hydroelectric Plant [member] |  |
Disclosure Of Financial Assets and Liabilities Of The Concession [Line Items] |  |
Concession expiration date | 2015-07 |
Installed capacity (MW) | MW | 396.00 |
Net balance of assets based on historical cost | R$ 71 |
Net balance of assets based on fair value (replacement cost) | R$ 413 |
Salto Grande Hydroelectric Plant [member] |  |
Disclosure Of Financial Assets and Liabilities Of The Concession [Line Items] |  |
Concession expiration date | 2015-07 |
Installed capacity (MW) | MW | 102.00 |
Net balance of assets based on historical cost | R$ 11 |
Net balance of assets based on fair value (replacement cost) | R$ 39 |
Itutinga Hydroelectric Plant [member] |  |
Disclosure Of Financial Assets and Liabilities Of The Concession [Line Items] |  |
Concession expiration date | 2015-07 |
Installed capacity (MW) | MW | 52.00 |
Net balance of assets based on historical cost | R$ 4 |
Net balance of assets based on fair value (replacement cost) | R$ 7 |
Camargos hydroelectric plant [member] |  |
Disclosure Of Financial Assets and Liabilities Of The Concession [Line Items] |  |
Concession expiration date | 2015-07 |
Installed capacity (MW) | MW | 46.00 |
Net balance of assets based on historical cost | R$ 8 |
Net balance of assets based on fair value (replacement cost) | R$ 23 |
Piau Small Hydroelectric Plant [member] |  |
Disclosure Of Financial Assets and Liabilities Of The Concession [Line Items] |  |
Concession expiration date | 2015-07 |
Installed capacity (MW) | MW | 18.01 |
Net balance of assets based on historical cost | R$ 2 |
Net balance of assets based on fair value (replacement cost) | R$ 9 |
Gafanhoto Small Hydroelectric Plant [member] |  |
Disclosure Of Financial Assets and Liabilities Of The Concession [Line Items] |  |
Concession expiration date | 2015-07 |
Installed capacity (MW) | MW | 14.00 |
Net balance of assets based on historical cost | R$ 1 |
Net balance of assets based on fair value (replacement cost) | R$ 10 |
Peti Small Hydroelectric Plant [member] |  |
Disclosure Of Financial Assets and Liabilities Of The Concession [Line Items] |  |
Concession expiration date | 2015-07 |
Installed capacity (MW) | MW | 9.40 |
Net balance of assets based on historical cost | R$ 1 |
Net balance of assets based on fair value (replacement cost) | R$ 8 |
Dona Rita Small Hydroelectric Plant [member] |  |
Disclosure Of Financial Assets and Liabilities Of The Concession [Line Items] |  |
Concession expiration date | 2013-09 |
Installed capacity (MW) | MW | 2.41 |
Net balance of assets based on historical cost | R$ 1 |
Net balance of assets based on fair value (replacement cost) | R$ 1 |
Tronqueiras Small Hydroelectric Plant [member] |  |
Disclosure Of Financial Assets and Liabilities Of The Concession [Line Items] |  |
Concession expiration date | 2015-07 |
Installed capacity (MW) | MW | 8.50 |
Net balance of assets based on historical cost | R$ 2 |
Net balance of assets based on fair value (replacement cost) | R$ 12 |
Joasal Small Hydroelectric Plant [member] |  |
Disclosure Of Financial Assets and Liabilities Of The Concession [Line Items] |  |
Concession expiration date | 2015-07 |
Installed capacity (MW) | MW | 8.40 |
Net balance of assets based on historical cost | R$ 1 |
Net balance of assets based on fair value (replacement cost) | R$ 8 |
Martins Small Hydroelectric Plant [member] |  |
Disclosure Of Financial Assets and Liabilities Of The Concession [Line Items] |  |
Concession expiration date | 2015-07 |
Installed capacity (MW) | MW | 7.70 |
Net balance of assets based on historical cost | R$ 2 |
Net balance of assets based on fair value (replacement cost) | R$ 4 |
Cajuru Small Hydroelectric Plant [member] |  |
Disclosure Of Financial Assets and Liabilities Of The Concession [Line Items] |  |
Concession expiration date | 2015-07 |
Installed capacity (MW) | MW | 7.20 |
Net balance of assets based on historical cost | R$ 4 |
Net balance of assets based on fair value (replacement cost) | R$ 4 |
Paciencia Small Hydroelectric Plant [member] |  |
Disclosure Of Financial Assets and Liabilities Of The Concession [Line Items] |  |
Concession expiration date | 2015-07 |
Installed capacity (MW) | MW | 4.08 |
Net balance of assets based on historical cost | R$ 1 |
Net balance of assets based on fair value (replacement cost) | R$ 4 |
Marmelos Small Hydroelectric Plant [member] |  |
Disclosure Of Financial Assets and Liabilities Of The Concession [Line Items] |  |
Concession expiration date | 2015-07 |
Installed capacity (MW) | MW | 4.00 |
Net balance of assets based on historical cost | R$ 1 |
Net balance of assets based on fair value (replacement cost) | R$ 4 |
Volta grande hydroelectric plant [member] |  |
Disclosure Of Financial Assets and Liabilities Of The Concession [Line Items] |  |
Concession expiration date | 2017-02 |
Installed capacity (MW) | MW | 380.00 |
Net balance of assets based on historical cost | R$ 26 |
Net balance of assets based on fair value (replacement cost) | R$ 70 |
Miranda hydroelectric plant [member] |  |
Disclosure Of Financial Assets and Liabilities Of The Concession [Line Items] |  |
Concession expiration date | 2016-12 |
Installed capacity (MW) | MW | 408.00 |
Net balance of assets based on historical cost | R$ 26 |
Net balance of assets based on fair value (replacement cost) | R$ 23 |
Jaguara hydroelectric plant [member] |  |
Disclosure Of Financial Assets and Liabilities Of The Concession [Line Items] |  |
Concession expiration date | 2013-08 |
Installed capacity (MW) | MW | 424.00 |
Net balance of assets based on historical cost | R$ 40 |
Net balance of assets based on fair value (replacement cost) | R$ 174 |
Sao simao hydroelectric plant [member] |  |
Disclosure Of Financial Assets and Liabilities Of The Concession [Line Items] |  |
Concession expiration date | 2015-01 |
Installed capacity (MW) | MW | 1,710.00 |
Net balance of assets based on historical cost | R$ 2 |
Net balance of assets based on fair value (replacement cost) | R$ 3 |

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