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FINANCIAL INSTRUMENTS - Measurement of fair value (Details) - BRL (R$) R$ in Thousands | Dec. 31, 2018 | Dec. 31, 2017
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FINANCIAL INSTRUMENTS |  |
Total financial assets | R$ 1,750,841 | R$ 1,886,067
Total financial liabilities | 17,339,894 | 18,925,008
Fair Value - Measured at Fair Value on a Recurring Basis |  |
FINANCIAL INSTRUMENTS |  |
Total financial assets | 1,750,841 | 1,886,067
Total financial liabilities | 17,339,894 | 18,925,008
Short-term debts | Fair Value - Measured at Fair Value on a Recurring Basis |  |
FINANCIAL INSTRUMENTS |  |
Current financial liabilities | 1,822,183 | 2,004,341
Unrealized losses on financial instruments |  |
FINANCIAL INSTRUMENTS |  |
Total financial liabilities | 5,245 | 1,267
Unrealized losses on financial instruments | Fair Value - Measured at Fair Value on a Recurring Basis |  |
FINANCIAL INSTRUMENTS |  |
Current financial liabilities | 5,245 |
Non-current financial liabilities |  | 1,267
Other current liabilities |  |
FINANCIAL INSTRUMENTS |  |
Total financial liabilities | 988,967 | 625,410
Other current liabilities | Fair Value - Measured at Fair Value on a Recurring Basis |  |
FINANCIAL INSTRUMENTS |  |
Current financial liabilities | 988,967 | 625,410
Long-term debt | Fair Value - Measured at Fair Value on a Recurring Basis |  |
FINANCIAL INSTRUMENTS |  |
Non-current financial liabilities | 11,545,658 | 14,457,315
Debentures |  |
FINANCIAL INSTRUMENTS |  |
Total financial liabilities | 1,538,873 | 47,928
Debentures | Fair Value - Measured at Fair Value on a Recurring Basis |  |
FINANCIAL INSTRUMENTS |  |
Non-current financial liabilities | 1,538,873 | 47,928
Obligation with FIDC |  |
FINANCIAL INSTRUMENTS |  |
Total financial liabilities | 938,526 | 1,135,077
Obligation with FIDC | Fair Value - Measured at Fair Value on a Recurring Basis |  |
FINANCIAL INSTRUMENTS |  |
Non-current financial liabilities | 938,526 | 1,135,077
Other non-current liabilities |  |
FINANCIAL INSTRUMENTS |  |
Total financial liabilities | 499,092 | 653,670
Other non-current liabilities | Fair Value - Measured at Fair Value on a Recurring Basis |  |
FINANCIAL INSTRUMENTS |  |
Non-current financial liabilities | 499,092 | 653,670
Short-term investments |  |
FINANCIAL INSTRUMENTS |  |
Total financial assets | 459,470 | 821,518
Short-term investments | Fair Value - Measured at Fair Value on a Recurring Basis |  |
FINANCIAL INSTRUMENTS |  |
Current financial assets | 459,470 | 821,518
Unrealized gains on financial instruments |  |
FINANCIAL INSTRUMENTS |  |
Total financial assets | 33,417 |
Unrealized gains on financial instruments | Fair Value - Measured at Fair Value on a Recurring Basis |  |
FINANCIAL INSTRUMENTS |  |
Current financial assets | 30,711 |
Other current assets |  |
FINANCIAL INSTRUMENTS |  |
Total financial assets | 780,423 | 469,737
Other current assets | Fair Value - Measured at Fair Value on a Recurring Basis |  |
FINANCIAL INSTRUMENTS |  |
Current financial assets | 780,423 | 469,737
Related parties |  |
FINANCIAL INSTRUMENTS |  |
Total financial assets | 27,939 | 51,839
Total financial liabilities | 1,350 |
Related parties | Fair Value - Measured at Fair Value on a Recurring Basis |  |
FINANCIAL INSTRUMENTS |  |
Non-current financial assets | 27,939 | 51,839
Non-current financial liabilities | 1,350 |
Unrealized gains on financial instruments, noncurrent | Fair Value - Measured at Fair Value on a Recurring Basis |  |
FINANCIAL INSTRUMENTS |  |
Non-current financial assets | 2,706 |
Other non-current assets |  |
FINANCIAL INSTRUMENTS |  |
Total financial assets | 449,592 | 542,973
Other non-current assets | Fair Value - Measured at Fair Value on a Recurring Basis |  |
FINANCIAL INSTRUMENTS |  |
Non-current financial assets | 449,592 | 542,973
Quoted Prices Active Markets for Identical Assets (Level 1) | Fair Value - Measured at Fair Value on a Recurring Basis |  |
FINANCIAL INSTRUMENTS |  |
Total financial assets | 114,027 | 238,008
Quoted Prices Active Markets for Identical Assets (Level 1) | Short-term investments | Fair Value - Measured at Fair Value on a Recurring Basis |  |
FINANCIAL INSTRUMENTS |  |
Current financial assets | 114,027 | 238,008
Quoted Prices in Non-Active Markets for Similar Assets (Level 2) | Fair Value - Measured at Fair Value on a Recurring Basis |  |
FINANCIAL INSTRUMENTS |  |
Total financial assets | 1,636,814 | 1,648,059
Total financial liabilities | 17,339,894 | 18,925,008
Quoted Prices in Non-Active Markets for Similar Assets (Level 2) | Short-term debts | Fair Value - Measured at Fair Value on a Recurring Basis |  |
FINANCIAL INSTRUMENTS |  |
Current financial liabilities | 1,822,183 | 2,004,341
Quoted Prices in Non-Active Markets for Similar Assets (Level 2) | Unrealized losses on financial instruments | Fair Value - Measured at Fair Value on a Recurring Basis |  |
FINANCIAL INSTRUMENTS |  |
Current financial liabilities | 5,245 |
Non-current financial liabilities |  | 1,267
Quoted Prices in Non-Active Markets for Similar Assets (Level 2) | Other current liabilities | Fair Value - Measured at Fair Value on a Recurring Basis |  |
FINANCIAL INSTRUMENTS |  |
Current financial liabilities | 988,967 | 625,410
Quoted Prices in Non-Active Markets for Similar Assets (Level 2) | Long-term debt | Fair Value - Measured at Fair Value on a Recurring Basis |  |
FINANCIAL INSTRUMENTS |  |
Non-current financial liabilities | 11,545,658 | 14,457,315
Quoted Prices in Non-Active Markets for Similar Assets (Level 2) | Debentures | Fair Value - Measured at Fair Value on a Recurring Basis |  |
FINANCIAL INSTRUMENTS |  |
Non-current financial liabilities | 1,538,873 | 47,928
Quoted Prices in Non-Active Markets for Similar Assets (Level 2) | Obligation with FIDC | Fair Value - Measured at Fair Value on a Recurring Basis |  |
FINANCIAL INSTRUMENTS |  |
Non-current financial liabilities | 938,526 | 1,135,077
Quoted Prices in Non-Active Markets for Similar Assets (Level 2) | Other non-current liabilities | Fair Value - Measured at Fair Value on a Recurring Basis |  |
FINANCIAL INSTRUMENTS |  |
Non-current financial liabilities | 499,092 | 653,670
Quoted Prices in Non-Active Markets for Similar Assets (Level 2) | Short-term investments | Fair Value - Measured at Fair Value on a Recurring Basis |  |
FINANCIAL INSTRUMENTS |  |
Current financial assets | 345,443 | 583,510
Quoted Prices in Non-Active Markets for Similar Assets (Level 2) | Unrealized gains on financial instruments | Fair Value - Measured at Fair Value on a Recurring Basis |  |
FINANCIAL INSTRUMENTS |  |
Current financial assets | 30,711 |
Quoted Prices in Non-Active Markets for Similar Assets (Level 2) | Other current assets | Fair Value - Measured at Fair Value on a Recurring Basis |  |
FINANCIAL INSTRUMENTS |  |
Current financial assets | 780,423 | 469,737
Quoted Prices in Non-Active Markets for Similar Assets (Level 2) | Related parties | Fair Value - Measured at Fair Value on a Recurring Basis |  |
FINANCIAL INSTRUMENTS |  |
Non-current financial assets | 27,939 | 51,839
Non-current financial liabilities | 1,350 |
Quoted Prices in Non-Active Markets for Similar Assets (Level 2) | Unrealized gains on financial instruments, noncurrent | Fair Value - Measured at Fair Value on a Recurring Basis |  |
FINANCIAL INSTRUMENTS |  |
Non-current financial assets | 2,706 |
Quoted Prices in Non-Active Markets for Similar Assets (Level 2) | Other non-current assets | Fair Value - Measured at Fair Value on a Recurring Basis |  |
FINANCIAL INSTRUMENTS |  |
Non-current financial assets | R$ 449,592 | R$ 542,973

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