FINANCIAL INSTRUMENTS - Measurement of fair value (Details) - BRL (R$) R$ in Thousands	Dec. 31, 2018	Dec. 31, 2017
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

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

Name:	ifrs-full_CurrentFinancialAssets
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

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

+ References

+ Details

Name:	ifrs-full_CurrentFinancialLiabilities
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

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.

+ References

No definition available.

+ Details

Name:	ifrs-full_DisclosureOfFinancialInstrumentsLineItems
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

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
-Name IFRS
-Number 7
-IssueDate 2018-01-01
-Paragraph 25
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2018-03-01&anchor=para_25&doctype=Standard
-URIDate 2018-03-16

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 7
-IssueDate 2018-01-01
-Paragraph 35H
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2018-03-01&anchor=para_35H&doctype=Standard
-URIDate 2018-03-16

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 7
-IssueDate 2018-01-01
-Paragraph 35I
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2018-03-01&anchor=para_35I&doctype=Standard
-URIDate 2018-03-16

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 7
-IssueDate 2018-01-01
-Paragraph 35M
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2018-03-01&anchor=para_35M&doctype=Standard
-URIDate 2018-03-16

Reference 5: http://www.xbrl.org/2003/role/exampleRef
-Name IFRS
-Number 7
-IssueDate 2018-01-01
-Paragraph 35N
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2018-03-01&anchor=para_35N&doctype=Standard
-URIDate 2018-03-16

+ Details

Name:	ifrs-full_FinancialAssets
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- 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]]

+ References

+ Details

Name:	ifrs-full_FinancialLiabilities
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

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

+ References

+ Details

Name:	ifrs-full_NoncurrentFinancialAssets
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

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

+ References

+ Details

Name:	ifrs-full_NoncurrentFinancialLiabilities
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant