Retirement Benefit Plans - Summary of Weighted Average Assumptions Used to Calculate the Defined Benefit Obligation (Detail)	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Pension Plans
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Discount rate	3.04%	3.78%
Rate of increase in future compensation	3.25%	3.25%
Non-Pension Post- Retirement Benefit Plans
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Discount rate	3.10%	3.88%
Rate of increase in future compensation	3.25%	3.25%
Medical trend rate	5.00%	5.00%

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 2019-01-01
-Paragraph 144
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=19&code=ifrs-tx-2019-en-r&anchor=para_144&doctype=Standard
-URIDate 2019-03-27

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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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Medical cost trend rate used as 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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Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table.

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