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Employee Defined Benefit Obligations - Summary of Quantitative Sensitivity Analyses Impact on Defined Benefit Obligation for Significant Assumptions (Details) - CAD ($) $ in Millions | Dec. 31, 2020 | Dec. 31, 2019
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Change in discount rate by 0.25% |  |
Disclosure of sensitivity analysis for actuarial assumptions [Line Items] |  |
Increase | $ (19.6) | $ (18.9)
Decrease | $ 20.3 | 19.6
Percentage of increase | 0.25% |
Percentage of decrease | 0.25% |
Change in pre-retirement inflation rate by 0.25% |  |
Disclosure of sensitivity analysis for actuarial assumptions [Line Items] |  |
Increase | $ 5.6 | 5.7
Decrease | $ (5.3) | (5.5)
Percentage of increase | 0.25% |
Percentage of decrease | 0.25% |
Change in salary growth by 0.25% |  |
Disclosure of sensitivity analysis for actuarial assumptions [Line Items] |  |
Increase | $ 1.2 | 1.0
Decrease | $ (1.2) | (1.0)
Percentage of increase | 0.25% |
Percentage of decrease | 0.25% |
Change in pension increase assumption by 0.25% |  |
Disclosure of sensitivity analysis for actuarial assumptions [Line Items] |  |
Increase | $ 12.9 | 10.5
Decrease | $ (12.3) | (9.2)
Percentage of increase | 0.25% |
Percentage of decrease | 0.25% |
Change in one year in the life expectancy |  |
Disclosure of sensitivity analysis for actuarial assumptions [Line Items] |  |
Increase | $ 13.3 | 11.8
Decrease | $ (13.3) | $ (11.8)

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- Definition The increase (decrease) in a defined benefit obligation that would have been caused by a decrease in a significant actuarial assumption that was reasonably possible at the end of the reporting period. [Refer: Actuarial assumptions [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 19 -IssueDate 2020-01-01 -Paragraph 145 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=19&code=ifrs-tx-2020-en-r&anchor=para_145_a&doctype=Standard -URIDate 2020-01-01 + Details
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- Definition The increase (decrease) in a defined benefit obligation that would have been caused by an increase in a significant actuarial assumption that was reasonably possible at the end of the reporting period. [Refer: Actuarial assumptions [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 19 -IssueDate 2020-01-01 -Paragraph 145 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=19&code=ifrs-tx-2020-en-r&anchor=para_145_a&doctype=Standard -URIDate 2020-01-01 + Details
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