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EMPLOYEE BENEFITS (Tables) | 12 Months Ended
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Dec. 31, 2017
Disclosure of net defined benefit liability (asset) [line items] |
Schedule of total assets and liabilities of all types of employee benefits granted |
|  | 2017 |  | 2016 |
Plan assets - Defined contribution pension plan |  | 1,149 |  | 1,490 |
Plan assets - Defined benefit pension plan |  | — |  | 55,307 |
Total assets |  | 1,149 |  | 56,797 |
Actuarial liabilities - Defined benefit pension plan |  | 1,084,758 |  | 1,144,080 |
Acturial liabilities - Post-employment health care benefit |  | 316,230 |  | 305,447 |
Retirement and termination benefit liabilities |  | 23,876 |  | 55,276 |
Total liabilities |  | 1,424,864 |  | 1,504,803 |
Current |  | 253 |  | 409 |
Non-current |  | 1,424,611 |  | 1,504,394 |
Post-employment defined benefit pension plans |
Disclosure of net defined benefit liability (asset) [line items] |
Summary of sensitivity analysis |
|  | 1% Increase |  | 1% Decrease |
Discount rate |  | (19,286 | ) | 15,457 |
Defined benefit pension plan |
Disclosure of net defined benefit liability (asset) [line items] |
Schedule of current expenses of benefit plans |
|  | 2017 |  | 2016 |  | 2015 |
Cost of current service |  | 60,595 |  | 57,619 |  | 121,962 |
Interest expense |  | 90,381 |  | 199,389 |  | 226,406 |
Return on plan assets |  | (64,128 | ) | (186,856 | ) | (216,005 | )
Past service cost |  | 1,082 |  | 2,788 |  | (151,685 | )
Curtailment |  | — |  | — |  | (4,510 | )
Settlement |  | (566 | ) | 609 |  | — |
Interest cost on unrecoverable surplus |  | 21,211 |  | 22,916 |  | 23,515 |
Net pension cost |  | 108,575 |  | 96,465 |  | (317 | )
Schedule of reconciliations of assets and liabilities of benefit plans |
|  | 2017 |  | 2016 |
Present value of defined benefit obligation |  | (4,314,592 | ) | (4,174,653 | )
Fair value of plan assets |  | 3,456,613 |  | 3,292,890 |
Asset ceiling restrictions on recognition of net funded assets |  | (226,779 | ) | (207,010 | )
Net |  | (1,084,758 | ) | (1,088,773 | )
Plan assets |  | — |  | 55,307 |
Defined benefit obligation |  | (1,084,758 | ) | (1,144,080 | )
Schedule of variation of plan obligations and assets |
|  | 2017 |  | 2016 |  | 2015 |
Variation of the plan obligations |  |  |  |  |  |  |
Obligation at the begining of the year |  | 4,174,653 |  | 4,739,299 |  | 3,791,670 |
Cost of service |  | 60,595 |  | 57,619 |  | 121,962 |
Interest expense |  | 195,557 |  | 199,389 |  | 226,406 |
Payments of the benefits |  | (335,471 | ) | (317,505 | ) | (398,778 | )
Past service cost |  | 1,082 |  | 2,788 |  | (114,899 | )
Curtailment |  | — |  | — |  | (41,296 | )
Settlement |  | (52,035 | ) | 609 |  | — |
Acturial remeasurements |  | 235,549 |  | 186,905 |  | (202,749 | )
Liabilities held for sale (note 3.4) |  | (101,794 | ) | — |  | — |
Exchange Variance |  | 136,456 |  | (694,451 | ) | 1,356,983 |
Obligation at the end of the year |  | 4,314,592 |  | 4,174,653 |  | 4,739,299 |
|  | 2017 |  | 2016 |  | 2015 |
Variation of the plan assets |  |  |  |  |  |  |
Fair value of the plan assets at the begining 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 | ) | — |
Payments of benefits |  | (335,471 | ) | (317,505 | ) | (398,778 | )
Remeasurement |  | 232,214 |  | 109,153 |  | (235,275 | )
Assets held for sale (note 3.4) |  | (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 |  | 3,865,411 |
Summary of actuarial gains and losses recognized in other comprehensive income |
|  | 2017 |  | 2016 |  | 2015 |
Remeasurements |  | (232,214 | ) | (109,153 | ) | 235,275 |
Actuarial Remeasurements |  | 235,549 |  | 186,905 |  | (202,749 | )
Restriction recognized in Other Comprehensive Income |  | (1,696 | ) | 3,065 |  | (44,453 | )
Remeasurements recognized in Other Comprehensive Income |  | 1,639 |  | 80,817 |  | (11,927 | )
Summary of historical actuarial remeasurements |
|  | 2017 |  | 2016 |  | 2015 |  | 2014 |  | 2013 |
Present value of defined benefit obligation |  | (4,314,592 | ) | (4,174,653 | ) | (4,739,299 | ) | (3,791,670 | ) | (3,113,818 | )
Fair value of the plan assets |  | 3,456,613 |  | 3,292,890 |  | 3,865,411 |  | 3,319,133 |  | 3,081,582 |
Surplus (Deficit) |  | (857,979 | ) | (881,763 | ) | (873,888 | ) | (472,537 | ) | (32,236 | )
Experience adjustments on plan liabilities (Gain) |  | 235,549 |  | 186,905 |  | (202,749 | ) | 466,829 |  | (272,767 | )
Experience adjustments on plan assets (Gain) |  | (232,214 | ) | (109,153 | ) | 235,275 |  | (69,748 | ) | 33,417 |
Summary of allocation for plan assets |
|  | 2017 |
|  | Brazilian Plans |  | American Plans |
Fixed income |  | 98.0 | % | 48.3 | %
Variable income |  | — |  | 45.0 | %
Others |  | 2.0 | % | 6.7 | %
Total |  | 100.0 | % | 100.0 | %
|  | 2016 |
|  | Brazilian Plans |  | American Plans |
Fixed income |  | 97.0 | % | 45.8 | %
Variable income |  | — |  | 48.5 | %
Others |  | 3.0 | % | 5.7 | %
Total |  | 100.0 | % | 100.0 | %
Summary of assumptions |
|  | 2017 |
|  | Brazilian Plan |  | North America Plan |
Average discount rate |  | 9.84% |  | 3.25% - 4.25% |
Rate of increase in compensation |  | Not applicable |  | 3.00% |
Mortality table |  | AT-2000 per sex |  | RP-2006 and MP-2017 |
Mortality table of disabled |  | AT-2000 per sex |  | RP-2006 and MP-2017 |
Rate of rotation |  | Based on service and salary level/null |  | Based on age and/or the service |
|  | 2016 |
|  | Brazilian Plan |  | North America Plan |
Average discount rate |  | 10.87% |  | 3.75% - 4.25% |
Rate of increase in compensation |  | Not applicable |  | 3.25% |
Mortality table |  | RP-2000 |  | CPM-2014 and RP-2014 |
Mortality table of disabled |  | AT-2000 per sex |  | Rates by age |
Rate of rotation |  | Based on service and salary level/null |  | Based on age and/or the service |
Post-employment health care benefit |
Disclosure of net defined benefit liability (asset) [line items] |
Summary of sensitivity analysis |
|  | 1% Increase |  | 1% Decrease |
Effect over total service costs and interest costs |  | 92 |  | (765 | )
Effect over benefit plan obligations |  | 37,871 |  | (47,434 | )
Schedule of current expenses of benefit plans |
|  | 2017 |  | 2016 |  | 2015 |
Current service cost |  | 4,441 |  | 4,481 |  | 5,935 |
Interests expense |  | 12,162 |  | 15,494 |  | 18,981 |
Past service cost |  | 5,769 |  | (75,787 | ) | — |
Net cost pension benefit |  | 22,372 |  | (55,812 | ) | 24,916 |
Schedule of reconciliations of assets and liabilities of benefit plans |
|  | 2017 |  | 2016 |
Present value of obligations |  | (316,364 | ) | (305,447 | )
Total net liabilities |  | (316,364 | ) | (305,447 | )
Schedule of variation of plan obligations and assets |
|  | 2017 |  | 2016 |  | 2015 |
Change in benefit obligation |  |  |  |  |  |  |
Benefit obligation at beginning of the year |  | 305,447 |  | 446,842 |  | 351,538 |
Cost of service |  | 4,441 |  | 4,481 |  | 5,935 |
Interest expense |  | 12,162 |  | 15,494 |  | 18,981 |
Past service cost |  | 5,769 |  | (75,787 | ) | — |
Contributions from participants |  | 1,556 |  | 2,212 |  | 2,206 |
Payment of benefits |  | (14,230 | ) | (14,799 | ) | (17,245 | )
Remeasurements |  | (14,452 | ) | (3,673 | ) | (45,884 | )
Exchange variations |  | 15,671 |  | (69,323 | ) | 131,311 |
Benefit obligation at the end of the year |  | 316,364 |  | 305,447 |  | 446,842 |
|  | 2017 |  | 2016 |  | 2015 |
Change in plan assets |  |  |  |  |  |  |
Contributions from sponsors |  | 12,572 |  | 12,463 |  | 14,733 |
Contributions from participants |  | 1,556 |  | 2,212 |  | 2,206 |
Payments of benefits |  | (14,128 | ) | (14,675 | ) | (16,939 | )
Fair value of plan assets at end of the year |  | — |  | — |  | — |
Summary of actuarial gains and losses recognized in other comprehensive income |
|  |  |  | 2017 |  | 2016 |  | 2015 |
Losses on actuarial obligation |  |  |  | 14,452 |  | (3,673 | ) | (45,884 | )
Actuarial losses recognized in Equity |  |  |  | 14,452 |  | (3,673 | ) | (45,884 | )
Summary of historical actuarial remeasurements |
|  | 2017 |  | 2016 |  | 2015 |  | 2014 |  | 2013 |
Present value of defined benefit obligation |  | (316,364 | ) | (305,488 | ) | (446,843 | ) | (351,538 | ) | (369,086 | )
Deficit |  | (316,364 | ) | (305,488 | ) | (446,843 | ) | (351,538 | ) | (369,086 | )
Experience adjustments on plan liabilities |  | (14,452 | ) | (3,673 | ) | (45,884 | ) | 42,345 |  | (20,980 | )
Summary of assumptions |
|  | 2017 |  | 2016 |
Average discount rate |  | 3.25% - 3.50% |  | 3.75% - 4.25% |
Health treatment - rate assumed next year |  | 6.88% - 7.60% |  | 6.40% - 6.80% |
Health treatment - Assumed rate of decline in the cost to achieve in the years of 2026 to 2041 |  | 4.00% - 4.50% |  | 4.00% - 4.50% |

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