FINANCIAL INSTRUMENTS - Measurement of fair value (Details) - BRL (R$) R$ in Thousands	Dec. 31, 2020	Dec. 31, 2019
FINANCIAL INSTRUMENTS
Total financial assets	R$ 4,357,884	R$ 4,834,178
Total financial liabilities	19,838,551	18,184,601
Fair Value - Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Total financial assets	4,357,884	4,834,178
Total financial liabilities	19,838,551	18,184,601
Short-term debts \| Fair Value - Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Current financial liabilities	1,424,043	1,544,211
Long-term debt \| Fair Value - Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Non-current financial liabilities	13,188,891	11,594,612
Debentures
FINANCIAL INSTRUMENTS
Total financial liabilities	2,902,417	2,911,044
Debentures \| Fair Value - Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Current financial liabilities	7,463	18,015
Non-current financial liabilities	2,894,954	2,893,029
Fair value of derivatives
FINANCIAL INSTRUMENTS
Total financial liabilities	971
Fair value of derivatives \| Fair Value - Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Current financial liabilities	971
Related parties
FINANCIAL INSTRUMENTS
Total financial liabilities	22,855
Related parties \| Fair Value - Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Non-current financial liabilities	22,855
Obligation with FIDC
FINANCIAL INSTRUMENTS
Total financial liabilities	987,406	1,018,501
Obligation with FIDC \| Fair Value - Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Non-current financial liabilities	42,893	1,018,501
Lease liabilities
FINANCIAL INSTRUMENTS
Current financial liabilities	944,513
Other current liabilities
FINANCIAL INSTRUMENTS
Total financial liabilities	797,082	666,858
Other current liabilities \| Fair Value - Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Current financial liabilities	797,082	666,858
Other non-current liabilities
FINANCIAL INSTRUMENTS
Total financial liabilities	514,886	449,375
Other non-current liabilities \| Fair Value - Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Non-current financial liabilities	514,886	449,375
Short-term investments
FINANCIAL INSTRUMENTS
Total financial assets	3,041,143	3,652,949
Short-term investments \| Fair Value - Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Current financial assets	3,041,143	3,652,949
Fair value of derivatives
FINANCIAL INSTRUMENTS
Total financial assets		2,846
Fair value of derivatives \| Fair Value - Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Current financial assets		2,846
Related parties \| Fair Value - Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Non-current financial assets	134,354	95,445
Other current assets
FINANCIAL INSTRUMENTS
Total financial assets	591,523	618,769
Other current assets \| Fair Value - Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Current financial assets	591,523	618,769
Other non-current assets
FINANCIAL INSTRUMENTS
Total financial assets	590,864	464,169
Other non-current assets \| Fair Value - Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Non-current financial assets	590,864	464,169
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	4,357,884	4,834,178
Total financial liabilities	19,838,551	18,184,601
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	1,424,043	1,544,211
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	13,188,891	11,594,612
Quoted Prices in Non-Active Markets for Similar Assets (Level 2) \| Debentures \| Fair Value - Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Current financial liabilities	7,463	18,015
Non-current financial liabilities	2,894,954	2,893,029
Quoted Prices in Non-Active Markets for Similar Assets (Level 2) \| Fair value of derivatives \| Fair Value - Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Current financial liabilities	971
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 liabilities	22,855
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	42,893	1,018,501
Quoted Prices in Non-Active Markets for Similar Assets (Level 2) \| Lease liabilities
FINANCIAL INSTRUMENTS
Current financial liabilities	944,513
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	797,082	666,858
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	514,886	449,375
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	3,041,143	3,652,949
Quoted Prices in Non-Active Markets for Similar Assets (Level 2) \| Fair value of derivatives \| Fair Value - Measured at Fair Value on a Recurring Basis
FINANCIAL INSTRUMENTS
Current financial assets		2,846
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	134,354	95,445
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	591,523	618,769
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$ 590,864	R$ 464,169

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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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]

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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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