FINANCIAL INSTRUMENTS - Measurement of fair value (Details) - BRL (R$) R$ in Thousands	Dec. 31, 2017	Dec. 31, 2016
FINANCIAL INSTRUMENTS
Total financial assets	R$ 9,291,006	R$ 12,712,924
Total financial liabilities	22,104,962	25,257,075
Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Total financial assets	9,291,006	12,712,924
Total financial liabilities	22,104,962	25,257,075
Trade accounts payable
FINANCIAL INSTRUMENTS
Total financial liabilities	3,179,954	2,743,818
Trade accounts payable \| Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Current financial liabilities	3,179,954	2,743,818
Short-term debts \| Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Current financial liabilities	2,004,341	4,458,220
Unrealized losses on financial instruments
FINANCIAL INSTRUMENTS
Non-current financial liabilities	1,267
Total financial liabilities	1,267	6,584
Unrealized losses on financial instruments \| Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Current financial liabilities		6,584
Other current liabilities
FINANCIAL INSTRUMENTS
Total financial liabilities	625,410	514,599
Other current liabilities \| Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Current financial liabilities	625,410	514,599
Long-term debt \| Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Non-current financial liabilities	14,457,315	15,959,590
Debentures
FINANCIAL INSTRUMENTS
Total financial liabilities	47,928	165,423
Debentures \| Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Non-current financial liabilities	47,928	165,423
FIDC Obligation
FINANCIAL INSTRUMENTS
Total financial liabilities	1,135,077	1,007,259
FIDC Obligation \| Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Non-current financial liabilities	1,135,077	1,007,259
Other non-current liabilities
FINANCIAL INSTRUMENTS
Total financial liabilities	653,670	401,582
Other non-current liabilities \| Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Non-current financial liabilities	653,670	401,582
Cash and cash equivalents
FINANCIAL INSTRUMENTS
Total financial assets	2,555,338	5,063,383
Cash and cash equivalents \| Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Current financial assets	2,555,338	5,063,383
Short-term investments
FINANCIAL INSTRUMENTS
Total financial assets	821,518	1,024,411
Short-term investments \| Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Current financial assets	821,518	1,024,411
Trade accounts receivable
FINANCIAL INSTRUMENTS
Total financial assets	2,798,420	3,576,699
Trade accounts receivable \| Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Current financial assets	2,798,420	3,576,699
Unrealized gains on financial instruments
FINANCIAL INSTRUMENTS
Total financial assets		12,951
Unrealized gains on financial instruments \| Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Current financial assets		2,557
Other current assets
FINANCIAL INSTRUMENTS
Total financial assets	469,737	668,895
Other current assets \| Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Current financial assets	469,737	668,895
Related parties
FINANCIAL INSTRUMENTS
Total financial assets	51,839	57,541
Related parties \| Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Non-current financial assets	51,839	57,541
Unrealized gains on financial instruments, noncurrent \| Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Non-current financial assets		10,394
Judicial deposits
FINANCIAL INSTRUMENTS
Total financial assets	2,051,181	1,861,784
Judicial deposits \| Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Non-current financial assets	2,051,181	1,861,784
Other non-current assets
FINANCIAL INSTRUMENTS
Total financial assets	542,973	447,260
Other non-current assets \| Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Non-current financial assets	542,973	447,260
Quoted Prices Active Markets for Identical Assets (Level 1) \| Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Total financial assets	238,008	458,639
Quoted Prices Active Markets for Identical Assets (Level 1) \| Short-term investments \| Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Current financial assets	238,008	458,639
Quoted Prices in Non-Active Markets for Similar Assets (Level 2) \| Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Total financial assets	9,052,998	12,254,285
Total financial liabilities	22,104,962	25,257,075
Quoted Prices in Non-Active Markets for Similar Assets (Level 2) \| Trade accounts payable \| Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Current financial liabilities	3,179,954	2,743,818
Quoted Prices in Non-Active Markets for Similar Assets (Level 2) \| Short-term debts \| Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Current financial liabilities	2,004,341	4,458,220
Quoted Prices in Non-Active Markets for Similar Assets (Level 2) \| Unrealized losses on financial instruments
FINANCIAL INSTRUMENTS
Non-current financial liabilities	1,267
Quoted Prices in Non-Active Markets for Similar Assets (Level 2) \| Unrealized losses on financial instruments \| Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Current financial liabilities		6,584
Quoted Prices in Non-Active Markets for Similar Assets (Level 2) \| Other current liabilities \| Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Current financial liabilities	625,410	514,599
Quoted Prices in Non-Active Markets for Similar Assets (Level 2) \| Long-term debt \| Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Non-current financial liabilities	14,457,315	15,959,590
Quoted Prices in Non-Active Markets for Similar Assets (Level 2) \| Debentures \| Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Non-current financial liabilities	47,928	165,423
Quoted Prices in Non-Active Markets for Similar Assets (Level 2) \| FIDC Obligation \| Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Non-current financial liabilities	1,135,077	1,007,259
Quoted Prices in Non-Active Markets for Similar Assets (Level 2) \| Other non-current liabilities \| Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Non-current financial liabilities	653,670	401,582
Quoted Prices in Non-Active Markets for Similar Assets (Level 2) \| Cash and cash equivalents \| Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Current financial assets	2,555,338	5,063,383
Quoted Prices in Non-Active Markets for Similar Assets (Level 2) \| Short-term investments \| Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Current financial assets	583,510	565,772
Quoted Prices in Non-Active Markets for Similar Assets (Level 2) \| Trade accounts receivable \| Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Current financial assets	2,798,420	3,576,699
Quoted Prices in Non-Active Markets for Similar Assets (Level 2) \| Unrealized gains on financial instruments \| Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Current financial assets		2,557
Quoted Prices in Non-Active Markets for Similar Assets (Level 2) \| Other current assets \| Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Current financial assets	469,737	668,895
Quoted Prices in Non-Active Markets for Similar Assets (Level 2) \| Related parties \| Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Non-current financial assets	51,839	57,541
Quoted Prices in Non-Active Markets for Similar Assets (Level 2) \| Unrealized gains on financial instruments, noncurrent \| Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Non-current financial assets		10,394
Quoted Prices in Non-Active Markets for Similar Assets (Level 2) \| Judicial deposits \| Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Non-current financial assets	2,051,181	1,861,784
Quoted Prices in Non-Active Markets for Similar Assets (Level 2) \| Other non-current assets \| Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Non-current financial assets	R$ 542,973	R$ 447,260

The amount of current financial assets. [Refer: Financial assets]

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The amount of current financial liabilities. [Refer: Financial liabilities]

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Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table.

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No definition available.

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The amount of assets that are: (a) cash; (b) an equity instrument of another entity; (c) a contractual right: (i) to receive cash or another financial asset from another entity; or (ii) to exchange financial assets or financial liabilities with another entity under conditions that are potentially favourable to the entity; or (d) a contract that will, or may be, settled in the entity’s own equity instruments and is: (i) a non-derivative for which the entity is, or may be, obliged to receive a variable number of the entity’s own equity instruments; or (ii) a derivative that will, or may be, settled other than by the exchange of a fixed amount of cash or another financial asset for a fixed number of the entity’s own equity instruments. For this purpose the entity’s own equity instruments do not include puttable financial instruments classified as equity instruments in accordance with paragraphs 16A-16B of IAS 32, instruments that impose on the entity an obligation to deliver to another party a pro rata share of the net assets of the entity only on liquidation and are classified as equity instruments in accordance with paragraphs 16C-16D of IAS 32, or instruments that are contracts for the future receipt or delivery of the entity’s own equity instruments. [Refer: Financial instruments, class [member]; Financial liabilities]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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- Definition

The amount of liabilities that are: (a) a contractual obligation: (i) to deliver cash or another financial asset to another entity; or (ii) to exchange financial assets or financial liabilities with another entity under conditions that are potentially unfavourable to the entity; or (b) a contract that will, or may be, settled in the entity’s own equity instruments and is: (i) a non-derivative for which the entity is, or may be, obliged to deliver a variable number of the entity’s own equity instruments; or (ii) a derivative that will, or may be, settled other than by the exchange of a fixed amount of cash or another financial asset for a fixed number of the entity’s own equity instruments. For this purpose, rights, options or warrants to acquire a fixed number of the entity’s own equity instruments for a fixed amount of any currency are equity instruments if the entity offers the rights, options or warrants pro rata to all of its existing owners of the same class of its own non-derivative equity instruments. Also, for those purposes the entity’s own equity instruments do not include puttable financial instruments that are classified as equity instruments in accordance with paragraphs 16A-16B of IAS 32, instruments that impose on the entity an obligation to deliver to another party a pro rata share of the net assets of the entity only on liquidation and are classified as equity instruments in accordance with paragraphs 16C-16D of IAS 32, or instruments that are contracts for the future receipt or delivery of the entity’s own equity instruments. As an exception, an instrument that meets the definition of a financial liability is classified as an equity instrument if it has all the features and meets the conditions in paragraphs 16A-16B or paragraphs 16C-16D of IAS 32. [Refer: Financial instruments, class [member]; Financial assets; Derivatives [member]]

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The amount of non-current financial assets. [Refer: Financial assets]

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The amount of non-current financial liabilities. [Refer: Financial liabilities]

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