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EMPLOYEE BENEFITS - Post-employment health care benefit plan - Assumptions (Details) - Post-employment health care benefit	Dec. 31, 2018	Dec. 31, 2017
Minimum
Summary of assumptions used to calculate the defined benefit plans
Average discount rate	3.75%	3.25%
Health treatment - rate assumed next year	6.60%	6.88%
Health treatment - Assumed rate of decline in the cost to achieve in the years of 2026 to 2041	4.00%	4.00%
Maximum
Summary of assumptions used to calculate the defined benefit plans
Average discount rate	4.25%	3.50%
Health treatment - rate assumed next year	6.75%	7.60%
Health treatment - Assumed rate of decline in the cost to achieve in the years of 2026 to 2041	4.40%	4.50%

X

- Definition

Medical cost trend rate for the next year after reporting period used as significant actuarial assumption to determine the present value of a defined benefit obligation.

+ References

No definition available.

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- Definition

Medical cost trend rate of decline used as significant actuarial assumption to determine the present value of a defined benefit obligation.

+ References

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- References

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- Definition

The discount rate used as the significant actuarial assumption to determine the present value of a defined benefit obligation. [Refer: Defined benefit obligation, at present value; Actuarial assumptions [member]]

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 19
-IssueDate 2018-01-01
-Paragraph 144
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-URIDate 2018-03-16

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