Pension obligations (Schedule of defined benefit plan, assumptions used) - (Details) - Pension obligations [Member] - Year	Dec. 31, 2019	Dec. 31, 2018
Defined benefit cost [Member]
Pension Obligations [Line Items]
Expected rate of salary increase	2.75%	2.75%
Defined benefit cost [Member] \| Benefit obligations [Member]
Pension Obligations [Line Items]
Discount rate	3.73%	3.45%
Defined benefit cost [Member] \| Service cost [Member]
Pension Obligations [Line Items]
Discount rate	3.75%	3.50%
Defined benefit cost [Member] \| Males [Member]
Pension Obligations [Line Items]
Average longevity at retirement age for current pensioners (years)	21.1	21.0
Defined benefit cost [Member] \| Females [Member]
Pension Obligations [Line Items]
Average longevity at retirement age for current pensioners (years)	23.9	23.7
Defined benefit obligation [Member]
Pension Obligations [Line Items]
Discount rate	3.08%	3.73%
Expected rate of salary increase	2.75%	2.75%
Defined benefit obligation [Member] \| Males [Member]
Pension Obligations [Line Items]
Average longevity at retirement age for current pensioners (years)	21.2	21.1
Average longevity at retirement age for current employees (future pensioners) (years)	23.0	23.0
Defined benefit obligation [Member] \| Females [Member]
Pension Obligations [Line Items]
Average longevity at retirement age for current pensioners (years)	23.9	23.9
Average longevity at retirement age for current employees (future pensioners) (years)	25.6	25.6

Average longevity at retirement age for current employees (future pensioners) (years)

No definition available.

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- Definition

Average longevity at retirement age for current pensioners (years)

+ References

No definition available.

+ Details

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- Definition

Represents information of pension obligations.

+ References

No definition available.

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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
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=19&date=2018-03-01&anchor=para_144&doctype=Standard
-URIDate 2018-03-16

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- Definition

The expected rate of salary increases 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]]

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