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Employee Future Benefits - Defined Benefit Obligation (Details) - CAD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2023 | Dec. 31, 2022
Disclosure of net defined benefit liability (asset) [line items] |  |
Defined benefit obligation, beginning of period | $ 158 |
Actuarial loss arising from demographic assumptions | 5 | $ (37)
Defined benefit obligation, ending of period | 162 | 158
Present value of defined benefit obligation |  |
Disclosure of net defined benefit liability (asset) [line items] |  |
Defined benefit obligation, beginning of period | 447 |
Defined benefit obligation, ending of period | 446 | 447
Registered |  |
Disclosure of net defined benefit liability (asset) [line items] |  |
Defined benefit obligation, beginning of period | 71 |
Defined benefit obligation, ending of period | 71 | 71
Registered | Present value of defined benefit obligation |  |
Disclosure of net defined benefit liability (asset) [line items] |  |
Defined benefit obligation, beginning of period | 345 | 469
Current service cost | 1 | 1
Interest cost | 16 | 13
Benefits paid | (36) | (57)
Actuarial loss arising from demographic assumptions | 1 |
Actuarial gain arising from financial assumptions | 12 | (83)
Actuarial loss arising from experience adjustments | 2 | 1
Change in foreign exchange rates | (1) | 1
Defined benefit obligation, ending of period | 340 | 345
Supplemental |  |
Disclosure of net defined benefit liability (asset) [line items] |  |
Defined benefit obligation, beginning of period | 70 |
Defined benefit obligation, ending of period | 74 | 70
Supplemental | Present value of defined benefit obligation |  |
Disclosure of net defined benefit liability (asset) [line items] |  |
Defined benefit obligation, beginning of period | 85 | 101
Current service cost | 1 | 1
Interest cost | 4 | 3
Benefits paid | (6) | (5)
Actuarial loss arising from demographic assumptions | 0 |
Actuarial gain arising from financial assumptions | 4 | (22)
Actuarial loss arising from experience adjustments | 1 | 7
Change in foreign exchange rates | 0 | 0
Defined benefit obligation, ending of period | 89 | 85
Other |  |
Disclosure of net defined benefit liability (asset) [line items] |  |
Defined benefit obligation, beginning of period | 17 |
Defined benefit obligation, ending of period | 17 | 17
Other | Present value of defined benefit obligation |  |
Disclosure of net defined benefit liability (asset) [line items] |  |
Defined benefit obligation, beginning of period | 17 | 23
Current service cost | 0 | 0
Interest cost | 1 | 0
Benefits paid | (2) | 1
Actuarial loss arising from demographic assumptions | 0 |
Actuarial gain arising from financial assumptions | 1 | (5)
Actuarial loss arising from experience adjustments | 0 | (2)
Change in foreign exchange rates | 0 | 0
Defined benefit obligation, ending of period | 17 | 17
Total | Present value of defined benefit obligation |  |
Disclosure of net defined benefit liability (asset) [line items] |  |
Defined benefit obligation, beginning of period | 447 | 593
Current service cost | 2 | 2
Interest cost | 21 | 16
Benefits paid | (44) | (61)
Actuarial loss arising from demographic assumptions | 1 |
Actuarial gain arising from financial assumptions | 17 | (110)
Actuarial loss arising from experience adjustments | 3 | 6
Change in foreign exchange rates | (1) | 1
Defined benefit obligation, ending of period | $ 446 | $ 447

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- Definition The decrease (increase) in a net defined benefit liability (asset) resulting from actuarial gains (losses) arising from changes in demographic assumptions that result in remeasurements of the net defined benefit liability (asset). Demographic assumptions deal with matters such as: (a) mortality; (b) rates of employee turnover, disability and early retirement; (c) the proportion of plan members with dependants who will be eligible for benefits; (d) the proportion of plan members who will select each form of payment option available under the plan terms; and (e) claim rates under medical plans. [Refer: Net defined benefit liability (asset)] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 19 -IssueDate 2023-01-01 -Paragraph 141 -Subparagraph c -Clause ii -URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=19&code=ifrs-tx-2023-en-r&anchor=para_141_c_ii&doctype=Standard -URIDate 2023-03-23 + Details
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- Definition The decrease (increase) in a net defined benefit liability (asset) resulting from actuarial gains (losses) arising from changes in financial assumptions that result in remeasurements of the net defined benefit liability (asset). Financial assumptions deal with items such as: (a) the discount rate; (b) benefit levels, excluding any cost of the benefits to be met by employees, and future salary; (c) in the case of medical benefits, future medical costs, including claim handling costs (ie the costs that will be incurred in processing and resolving claims, including legal and adjuster's fees); and (d) taxes payable by the plan on contributions relating to service before the reporting date or on benefits resulting from that service. [Refer: Net defined benefit liability (asset)] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 19 -IssueDate 2023-01-01 -Paragraph 141 -Subparagraph c -Clause iii -URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=19&code=ifrs-tx-2023-en-r&anchor=para_141_c_iii&doctype=Standard -URIDate 2023-03-23 + Details
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- Definition The increase (decrease) in the net defined benefit liability (asset) resulting from employee service in the current period. [Refer: Net defined benefit liability (asset)] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 19 -IssueDate 2023-01-01 -Paragraph 141 -Subparagraph a -URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=19&code=ifrs-tx-2023-en-r&anchor=para_141_a&doctype=Standard -URIDate 2023-03-23 + Details
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- Definition Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with members defined in one or many axes of the table. + References No definition available. + Details
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- Definition The decrease (increase) in the net defined benefit liability (asset) resulting from the gain (loss) on changes in the effect of limiting a net defined benefit asset to the asset ceiling, excluding amounts included in interest income or expense. [Refer: Interest income (expense); Net defined benefit liability (asset); Increase (decrease) in net defined benefit liability (asset) resulting from interest expense (income)] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 19 -IssueDate 2023-01-01 -Paragraph 141 -Subparagraph c -Clause iv -URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=19&code=ifrs-tx-2023-en-r&anchor=para_141_c_iv&doctype=Standard -URIDate 2023-03-23 + Details
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- Definition The increase (decrease) in the net defined benefit liability (asset) resulting from changes in foreign exchange rates. [Refer: Net defined benefit liability (asset)] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 19 -IssueDate 2023-01-01 -Paragraph 141 -Subparagraph e -URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=19&code=ifrs-tx-2023-en-r&anchor=para_141_e&doctype=Standard -URIDate 2023-03-23 + Details
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- Definition The increase (decrease) in the net defined benefit liability (asset) resulting from the passage of time. [Refer: Interest expense; Net defined benefit liability (asset)] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 19 -IssueDate 2023-01-01 -Paragraph 141 -Subparagraph b -URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=19&code=ifrs-tx-2023-en-r&anchor=para_141_b&doctype=Standard -URIDate 2023-03-23 + Details
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- Definition The amount of deficit or surplus in a defined benefit plan, adjusted for any effect of limiting a net defined benefit asset to the asset ceiling. [Refer: Defined benefit plans [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 19 -IssueDate 2023-01-01 -Paragraph 140 -Subparagraph a -URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=19&code=ifrs-tx-2023-en-r&anchor=para_140_a&doctype=Standard -URIDate 2023-03-23 + Details
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- Definition The decrease (increase) in the net defined benefit liability (asset) resulting from payments from the plan in respect of settlements. [Refer: Decrease (increase) in net defined benefit liability (asset) resulting from gains (losses) arising from settlements; Net defined benefit liability (asset); Defined benefit plans [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 19 -IssueDate 2023-01-01 -Paragraph 141 -Subparagraph g -URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=19&code=ifrs-tx-2023-en-r&anchor=para_141_g&doctype=Standard -URIDate 2023-03-23 + Details
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