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Pensions and Other Post Retirement Benefits - Actuarial assumptions (Details) - CAD ($) $ in Millions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2023 | Dec. 31, 2022
Pensions and Other Post Retirement Benefits |  |
Actual experience period | 5 years |
Pension Benefits |  |
Pensions and Other Post Retirement Benefits |  |
Discount rate | 4.60% | 5.10%
Rate of compensation increase | 3.00% | 3.00%
Pension Benefits | Discount rate |  |
Pensions and Other Post Retirement Benefits |  |
Increase in actuarial assumption (as a percent) | 1.00% |
Increase (decrease) in interest and service cost due to increase in actuarial assumption | $ (17) |
Increase (decrease) in service and interest cost due to decrease in actuarial assumption | 20 |
Increase (decrease) in net obligation due to increase in actuarial assumption | (767) |
Increase (decrease) in net obligation due to decrease in actuarial assumption | $ 963 |
Other Post-Retirement Benefits |  |
Pensions and Other Post Retirement Benefits |  |
Discount rate | 4.60% | 5.10%
Rate of compensation increase | 3.00% | 3.00%
Assumption of annual percentage of increase of healthcare costs | 5.00% |
Other Post-Retirement Benefits | Discount rate |  |
Pensions and Other Post Retirement Benefits |  |
Increase in actuarial assumption (as a percent) | 1.00% |
Increase (decrease) in net obligation due to increase in actuarial assumption | $ (58) |
Increase (decrease) in net obligation due to decrease in actuarial assumption | $ 70 |
Other Post-Retirement Benefits | Health care cost |  |
Pensions and Other Post Retirement Benefits |  |
Increase in actuarial assumption (as a percent) | 1.00% |
Increase (decrease) in interest and service cost due to increase in actuarial assumption | $ 1 |
Increase (decrease) in service and interest cost due to decrease in actuarial assumption | (1) |
Increase (decrease) in net obligation due to increase in actuarial assumption | 22 |
Increase (decrease) in net obligation due to decrease in actuarial assumption | $ (19) |

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- Definition 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]] + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 19 -IssueDate 2023-01-01 -Paragraph 144 -URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=19&code=ifrs-tx-2023-en-r&anchor=para_144&doctype=Standard -URIDate 2023-03-23 + Details
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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]] + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 19 -IssueDate 2023-01-01 -Paragraph 144 -URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=19&code=ifrs-tx-2023-en-r&anchor=para_144&doctype=Standard -URIDate 2023-03-23 + Details
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- Definition 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]] + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 19 -IssueDate 2023-01-01 -Paragraph 144 -URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=19&code=ifrs-tx-2023-en-r&anchor=para_144&doctype=Standard -URIDate 2023-03-23 + Details
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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 2023-01-01 -Paragraph 145 -Subparagraph a -URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=19&code=ifrs-tx-2023-en-r&anchor=para_145_a&doctype=Standard -URIDate 2023-03-23 + 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 2023-01-01 -Paragraph 145 -Subparagraph a -URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=19&code=ifrs-tx-2023-en-r&anchor=para_145_a&doctype=Standard -URIDate 2023-03-23 + Details
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- Definition The reasonably possible percentage of the increase in the actuarial assumption used to determine the present value of defined benefit obligation. [Refer: Actuarial assumptions [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 19 -IssueDate 2023-01-01 -Paragraph 145 -Subparagraph a -URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=19&code=ifrs-tx-2023-en-r&anchor=para_145_a&doctype=Standard -URIDate 2023-03-23 + Details
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