EMPLOYEE BENEFITS - Defined benefit pension plan - Variation of the plan assets (Details) - Defined benefit pension plan - BRL (R$) R$ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
EMPLOYEE BENEFITS
Fair value of the plan assets at the beginning of the year	R$ (1,088,773)
Return of the plan assets	64,128	R$ 186,856	R$ 216,005
Curtailment			(4,510)
Fair value of plan assets at the end of the year	(1,084,758)	(1,088,773)
Fair value of plan assets
EMPLOYEE BENEFITS
Fair value of the plan assets at the beginning of the year	3,292,890	3,865,411	3,319,133
Return of the plan assets	169,304	186,857	216,005
Contributions from sponsors	111,450	(47,574)	(14,986)
Curtailment			(5,248)
Settlement	(51,469)	(6,710)
Payment of benefits	(335,471)	(317,505)	(398,778)
Remeasurements	232,214	109,153	(235,275)
Assets held for sale	(73,127)
Exchange Variance	110,822	(496,742)	984,560
Fair value of plan assets at the end of the year	3,456,613	3,292,890	R$ 3,865,411
Value of shares included in fair value of plan assets	R$ 3,558	R$ 1,895

The decrease in the net defined benefit liability (asset) resulting from the curtailment of plan assets.

No definition available.

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- Definition

The fair value of the entity's own shares that are included in the fair value of defined benefit plan assets.

+ References

No definition available.

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- Definition

The decrease (increase) in net defined benefit liability (asset) resulting from contributions to a defined benefit plan by the employer. [Refer: Net defined benefit liability (asset); Defined benefit plans [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- 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.

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- Definition

The decrease (increase) in a net defined benefit liability (asset) resulting from the remeasurement of that net defined benefit liability (asset). [Refer: Net defined benefit liability (asset)]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition

The increase (decrease) in the net defined benefit liability (asset) resulting from business combinations and disposals. [Refer: Business combinations [member]; Net defined benefit liability (asset)]

+ References

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- Definition

The increase (decrease) in the net defined benefit liability (asset) resulting from changes in foreign exchange rates. [Refer: Net defined benefit liability (asset)]

+ References

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- Definition

The amount of deficit or surplus in a defined benefit plan, adjusted for any effect of limiting a net defined benefit asset to the asset ceiling. [Refer: Defined benefit plans [member]]

+ References

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- Definition

The decrease (increase) in the net defined benefit liability (asset) resulting from payments from the plan. [Refer: Net defined benefit liability (asset)]

+ References

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- Definition

The decrease (increase) in the net defined benefit liability (asset) resulting from payments from the plan in respect of settlements. [Refer: Gains (losses) arising from settlements, net defined benefit liability (asset); Net defined benefit liability (asset); Defined benefit plans [member]]

+ References

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- Definition

The decrease (increase) in the net defined benefit liability (asset) resulting from the return on plan assets. The return on plans assets is interest, dividends and other revenue derived from the plan assets, together with realised and unrealised gains or losses on the plan assets, less any costs of managing plan assets and less any tax payable by the plan itself, other than tax included in the actuarial assumptions used to measure the present value of the defined benefit obligation. [Refer: Plan assets [member]; Net defined benefit liability (asset); Actuarial assumptions [member]]

+ References

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