Post-retirement benefits - Summary of main assumptions rate for valuations of plans (Detail)	Dec. 31, 2019	Dec. 31, 2018
Canada [Member]
Disclosure of defined benefit plans [Line Items]
Discount rate	3.10%	3.90%
Inflation	1.60%	1.60%
Rate of increase in pensions	0.10%	0.20%
Rate of increase in salaries	2.80%	2.90%
UK [Member]
Disclosure of defined benefit plans [Line Items]
Discount rate	2.00%	2.80%
Inflation	2.90%	3.30%
Rate of increase in pensions	2.50%	2.90%
Rate of increase in salaries	3.50%	3.70%
United States of America [Member]
Disclosure of defined benefit plans [Line Items]
Discount rate	3.10%	4.20%
Inflation	2.00%	2.00%
Rate of increase in pensions	0.00%	0.00%
Rate of increase in salaries	3.50%	3.50%
Switzerland
Disclosure of defined benefit plans [Line Items]
Discount rate	0.20%	0.70%
Inflation	1.10%	1.20%
Rate of increase in pensions	0.20%	0.00%
Rate of increase in salaries	2.10%	2.20%

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 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]]

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- Definition

The expected rate of increases in pension 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]]

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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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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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No definition available.

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