EARNINGS (LOSS) PER SHARE - Diluted earnings (losses) per share (Details) - BRL (R$) R$ / shares in Units, shares in Thousands, R$ in Thousands	3 Months Ended	6 Months Ended	12 Months Ended
Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Diluted earnings per share
Resulted of the period attributable to controlling shareholders'	R$ 10,035,111	R$ (2,057,101)	R$ 7,277,867	R$ (15,479,631)	R$ (15,479,631)
Weighted average number of shares in the period (except treasury shares)			1,349,222		1,349,222
Adjustment by stock options			237
Weighted average number of shares (diluted)			1,349,459		1,349,222
Diluted loss per common share - R$	R$ 7.43640	R$ (1.52466)	R$ 5.39318	R$ (11.47301)	R$ (11.47301)

The weighted average number of ordinary shares outstanding plus the weighted average number of ordinary shares that would be issued on the conversion of all the dilutive potential ordinary shares into ordinary shares. [Refer: Ordinary shares [member]; Weighted average [member]]

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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), both adjusted for the effects of all dilutive potential ordinary shares. [Refer: Ordinary shares [member]; Weighted average [member]]

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The number of dilutive potential ordinary shares that relate to the assumed exercise of the entity's share options.

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The profit (loss) from continuing and discontinued operations attributable to owners of the parent. [Refer: Profit (loss)]

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The number of ordinary shares outstanding at the beginning of the period, adjusted by the number of ordinary shares bought back or issued during the period multiplied by a time-weighting factor.

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