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EMPLOYEE BENEFITS - Defined benefit pension plan - Historical actuarial remeasurements (Details) - Defined benefit pension plan - BRL (R$) R$ in Thousands | 12 Months Ended
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Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Historical actuarial remeasurements |  |  |  |  |
Present value of defined benefit obligation | R$ (5,921,285) | R$ (4,601,965) | R$ (4,391,251) | R$ (4,314,592) | R$ (4,174,653)
Fair value of plan assets | 4,652,000 | 3,656,891 | 3,568,934 | 3,456,613 | 3,292,890
Surplus (Deficit) | (1,269,285) | (945,074) | (822,317) | (857,979) | (881,763)
Present value of the defined benefit obligations |  |  |  |  |
Historical actuarial remeasurements |  |  |  |  |
Experience adjustments on plan liabilities | 467,106 | 546,911 | (370,083) | 235,549 | 186,905
Plan assets |  |  |  |  |
Historical actuarial remeasurements |  |  |  |  |
Experience adjustments on plan assets | R$ (334,675) | R$ (386,767) | R$ 253,301 | R$ (232,214) | R$ (109,153)

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- Definition The decrease (increase) in defined benefit liabilities resulting from actuarial gains (losses) arising from experience adjustments that result in remeasurements of the net defined benefit liability. Experience adjustments deal with the effects of differences between the previous actuarial assumptions and what has actually occurred. + References No definition available. + Details
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- Definition The decrease (increase) in plan assets resulting from actuarial gains (losses) arising from experience adjustments that result in fair value remeasurements of plan assets. Experience adjustments deal with the effects of differences between the previous actuarial assumptions and what has actually occurred. + References No definition available. + Details
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- References No definition available. + Details
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- Definition The present value, without deducting any plan assets, of expected future payments required to settle the obligation resulting from employee service in the current and prior periods. [Refer: Plan assets, at fair value] + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 19 -IssueDate 2020-01-01 -Paragraph 57 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=19&code=ifrs-tx-2020-en-r&anchor=para_57_a&doctype=Standard -URIDate 2020-01-01 + Details
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- Definition The fair value of defined benefit plan assets. Plan assets comprise assets held by a long-term employee benefit fund and qualifying insurance policies. [Refer: At fair value [member]] + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 19 -IssueDate 2020-01-01 -Paragraph 57 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=19&code=ifrs-tx-2020-en-r&anchor=para_57_a&doctype=Standard -URIDate 2020-01-01 + Details
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- Definition The fair value of any plan assets, less the present value of the defined benefit obligation. [Refer: Plan assets [member]] + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 19 -IssueDate 2020-01-01 -Paragraph 57 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=19&code=ifrs-tx-2020-en-r&anchor=para_57_a&doctype=Standard -URIDate 2020-01-01 + Details
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- Details
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- Details
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- Details
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