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20. Employees benefits (Details 11) | 12 Months Ended
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Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
SummaryOfEmployeeBenefitsLineItems [Line Items] |  |  |
Discount rate | 5.35% | 5.74% | 7.23%
Inflation rate | 3.96% | 4.87% | 6.49%
Future salary increase | 9.52% | 10.89% | 14.19%
Mortality table | AT-2000 | AT-2000 | AT-2000
Unfunded plan |  |  |
SummaryOfEmployeeBenefitsLineItems [Line Items] |  |  |
Discount rate | 5.30% | 5.71% | 7.25%
Inflation rate | 3.96% | 4.87% | 6.49%
Future salary increase | 6.04% | 6.97% | 8.62%
Mortality table | AT-2000 | AT-2000 | AT-2000

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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 2017-01-01 -Paragraph 144 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=19&date=2017-03-01&anchor=para_144&doctype=Standard -URIDate 2017-03-09 + Details
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- Definition The expected rate of inflation that is used as a significant actuarial assumption to determine the present value of a defined benefit obligation. [Refer: Defined benefit plans [member]; Defined benefit obligation, at present value; Actuarial assumptions [member]] + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 19 -IssueDate 2017-01-01 -Paragraph 144 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=19&date=2017-03-01&anchor=para_144&doctype=Standard -URIDate 2017-03-09 + Details
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- Definition Any other material assumption used as a significant actuarial assumption to determine the present value of a defined benefit obligation. [Refer: Actuarial assumptions [member]; Defined benefit obligation, at present value] + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 19 -IssueDate 2017-01-01 -Paragraph 144 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=19&date=2017-03-01&anchor=para_144&doctype=Standard -URIDate 2017-03-09 + Details
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