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v3.19.3.a.u2

Post-retirement benefits - Summary of maturity of defined benefit obligations (Detail) | 12 Months Ended
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Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Disclosure of defined benefit plans [Line Items] |  |  |
Proportion relating to current employees | 20.00% | 19.00% | 20.00%
Proportion relating to former employees not yet retired | 12.00% | 11.00% | 11.00%
Proportion relating to retirees | 68.00% | 70.00% | 69.00%
Defined benefit obligation | 100.00% | 100.00% | 100.00%
Average duration of obligations (years) | 14 years 4 months 24 days | 13 years 4 months 24 days | 13 years 10 months 24 days
Pension benefits [member] |  |  |
Disclosure of defined benefit plans [Line Items] |  |  |
Proportion relating to current employees | 20.00% |  |
Proportion relating to former employees not yet retired | 12.00% |  |
Proportion relating to retirees | 68.00% |  |
Defined benefit obligation | 100.00% |  |
Average duration of obligations (years) | 14 years 6 months |  |
Other Benefits [member] |  |  |
Disclosure of defined benefit plans [Line Items] |  |  |
Proportion relating to current employees | 19.00% |  |
Proportion relating to former employees not yet retired | 0.00% |  |
Proportion relating to retirees | 81.00% |  |
Defined benefit obligation | 100.00% |  |
Average duration of obligations (years) | 13 years 4 months 24 days |  |

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- Definition 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. + References No definition available. + Details
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- Definition The weighted average duration of a defined benefit obligation. [Refer: Weighted average [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 19 -IssueDate 2019-01-01 -Paragraph 147 -Subparagraph c -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=19&code=ifrs-tx-2019-en-r&anchor=para_147_c&doctype=Standard -URIDate 2019-03-27 + Details
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- Definition Defined benefit obligation maturity percentage. + References No definition available. + Details
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- Definition Defined benefit obligations relating to current employees maturity percentage. + References No definition available. + Details
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- Definition Defined benefit obligations relating to former employees not yet retired maturity percentage. + References No definition available. + Details
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- Definition Defined benefit obligations relating to retirees maturity percentage. + References No definition available. + Details
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- Details
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- Details
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