EMPLOYEE BENEFITS - Post-employment health care benefit plan - Funded status (Details) - Post-employment health care benefit - BRL (R$) R$ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Funded status of the post-employment health benefits plans
Total net liabilities	R$ (316,364)	R$ (305,447)
Present value of the defined benefit obligations
Funded status of the post-employment health benefits plans
Total net liabilities	R$ (316,364)	R$ (305,447)

The amount of deficit in a defined benefit plan. [Refer: Defined benefit plans [member]]

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 1
-IssueDate 2017-01-01
-Paragraph 55
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_55&doctype=Standard
-URIDate 2017-03-09

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