Provisions for Retirement Benefit Obligations - Principal actuarial assumptions (Details)	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Provisions for Retirement Benefit Obligations
Retirement age	65 years	65 years	65 years
Payroll taxes	41.41%	41.41%	41.41%
Salary growth rate	2.00%	2.00%	2.00%
Discount rate	0.35%	0.70%	1.60%
Threshold minimum maturity term for Eurozone AA rated corporate bonds	10 years

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]]

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 19
-IssueDate 2020-01-01
-Paragraph 144
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=19&code=ifrs-tx-2020-en-r&anchor=para_144&doctype=Standard
-URIDate 2020-01-01

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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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- Definition

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

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- References

No definition available.

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The expected rate of payroll taxes used as a significant actuarial assumption to determine the present value of a defined benefit obligation.

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- Definition

Threshold minimum maturity term of the investments, considered for determination of discount rate for actuarial assumptions used to determine the present value of a defined benefit obligation.

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No definition available.

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