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EARNINGS (LOSS) PER SHARE (EPS) - Basic (Details) - BRL (R$) R$ / shares in Units, R$ in Thousands | 12 Months Ended
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Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Basic numerator |  |  |
Net income (loss) available to owners of parent | R$ 2,303,868 | R$ (359,360) | R$ (2,890,811)
Basic denominator |  |  |
Basic earnings/(loss) per share | R$ 1.35 | R$ (0.21) | R$ (1.70)
Common shares |  |  |
Basic numerator |  |  |
Net income (loss) available to owners of parent | R$ 774,279 | R$ (120,267) | R$ (969,954)
Basic denominator |  |  |
Weighted-average outstanding shares, after deducting the average treasury shares | 571,929,945 | 571,929,945 | 571,929,945
Basic earnings/(loss) per share | R$ 1.35 | R$ (0.21) | R$ (1.70)
Preferred shares |  |  |
Basic numerator |  |  |
Net income (loss) available to owners of parent | R$ 1,529,589 | R$ (239,093) | R$ (1,920,857)
Basic denominator |  |  |
Weighted-average outstanding shares, after deducting the average treasury shares | 1,129,851,598 | 1,137,012,265 | 1,132,626,373
Basic earnings/(loss) per share | R$ 1.35 | R$ (0.21) | R$ (1.70)

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- Definition Number of [basic] shares or units, after adjustment for contingently issuable shares or units and other shares or units not deemed outstanding, determined by relating the portion of time within a reporting period that shares or units have been outstanding to the total time in that period. + References No definition available. + Details
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- Definition The amount of profit (loss) attributable to ordinary equity holders of the parent entity (the numerator) divided by the weighted average number of ordinary shares outstanding during the period (the denominator). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 33 -IssueDate 2018-01-01 -Paragraph 66 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=33&date=2018-03-01&anchor=para_66&doctype=Standard -URIDate 2018-03-16 + Details
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