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Employee Future Benefits - Defined Benefit Obligation (Details) - CAD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2024 | Dec. 31, 2023
Defined Benefit Pension And Other Post-Employment Benefit Plans [Roll Forward] |  |
Defined benefit obligation, beginning of period | $ 162 |
Actuarial gain arising from demographic assumptions | (9) | $ 5
Defined benefit obligation, ending of period | $ 154 | 162
Weighted average duration of defined benefit obligation | 9 years 9 months 18 days |
Present value of defined benefit obligation |  |
Defined Benefit Pension And Other Post-Employment Benefit Plans [Roll Forward] |  |
Defined benefit obligation, beginning of period | $ 446 |
Defined benefit obligation, ending of period | 411 | 446
Registered |  |
Defined Benefit Pension And Other Post-Employment Benefit Plans [Roll Forward] |  |
Defined benefit obligation, beginning of period | 71 |
Defined benefit obligation, ending of period | 62 | 71
Registered | Present value of defined benefit obligation |  |
Defined Benefit Pension And Other Post-Employment Benefit Plans [Roll Forward] |  |
Defined benefit obligation, beginning of period | 340 | 345
Current service cost | 1 | 1
Interest cost | 14 | 16
Benefits paid | (31) | (36)
Actuarial gain arising from demographic assumptions |  | 1
Actuarial gain arising from financial assumptions | 1 | 12
Actuarial gain arising from experience adjustments | 0 | 2
Effect of settlement from the termination of the U.S. defined benefit plan (Note 27) | (23) |
Change in foreign exchange rates | 1 | (1)
Defined benefit obligation, ending of period | 303 | 340
Supplemental |  |
Defined Benefit Pension And Other Post-Employment Benefit Plans [Roll Forward] |  |
Defined benefit obligation, beginning of period | 74 |
Defined benefit obligation, ending of period | 74 | 74
Supplemental | Present value of defined benefit obligation |  |
Defined Benefit Pension And Other Post-Employment Benefit Plans [Roll Forward] |  |
Defined benefit obligation, beginning of period | 89 | 85
Current service cost | 0 | 1
Interest cost | 4 | 4
Benefits paid | (5) | (6)
Actuarial gain arising from demographic assumptions |  | 0
Actuarial gain arising from financial assumptions | 1 | 4
Actuarial gain arising from experience adjustments | 1 | 1
Effect of settlement from the termination of the U.S. defined benefit plan (Note 27) | 0 |
Change in foreign exchange rates | 0 | 0
Defined benefit obligation, ending of period | 90 | 89
Other |  |
Defined Benefit Pension And Other Post-Employment Benefit Plans [Roll Forward] |  |
Defined benefit obligation, beginning of period | 17 |
Defined benefit obligation, ending of period | 18 | 17
Other | Present value of defined benefit obligation |  |
Defined Benefit Pension And Other Post-Employment Benefit Plans [Roll Forward] |  |
Defined benefit obligation, beginning of period | 17 | 17
Current service cost | 1 | 0
Interest cost | 1 | 1
Benefits paid | (1) | (2)
Actuarial gain arising from demographic assumptions |  | 0
Actuarial gain arising from financial assumptions | 0 | 1
Actuarial gain arising from experience adjustments | 0 | 0
Effect of settlement from the termination of the U.S. defined benefit plan (Note 27) | 0 |
Change in foreign exchange rates | 0 | 0
Defined benefit obligation, ending of period | 18 | 17
Total | Present value of defined benefit obligation |  |
Defined Benefit Pension And Other Post-Employment Benefit Plans [Roll Forward] |  |
Defined benefit obligation, beginning of period | 446 | 447
Current service cost | 2 | 2
Interest cost | 19 | 21
Benefits paid | (37) | (44)
Actuarial gain arising from demographic assumptions |  | 1
Actuarial gain arising from financial assumptions | 2 | 17
Actuarial gain arising from experience adjustments | 1 | 3
Effect of settlement from the termination of the U.S. defined benefit plan (Note 27) | (23) |
Change in foreign exchange rates | 1 | (1)
Defined benefit obligation, ending of period | $ 411 | $ 446

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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 2024-01-01 -Paragraph 141 -Subparagraph c -Clause ii -URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=19&code=ifrs-tx-2024-en-r&anchor=para_141_c_ii&doctype=Standard -URIDate 2024-03-27 + 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 2024-01-01 -Paragraph 141 -Subparagraph c -Clause iii -URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=19&code=ifrs-tx-2024-en-r&anchor=para_141_c_iii&doctype=Standard -URIDate 2024-03-27 + 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 2024-01-01 -Paragraph 141 -Subparagraph a -URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=19&code=ifrs-tx-2024-en-r&anchor=para_141_a&doctype=Standard -URIDate 2024-03-27 + 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 2024-01-01 -Paragraph 141 -Subparagraph c -Clause iv -URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=19&code=ifrs-tx-2024-en-r&anchor=para_141_c_iv&doctype=Standard -URIDate 2024-03-27 + Details
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- Definition The decrease (increase) in the net defined benefit liability (asset) resulting from settlements. Settlements are transactions that eliminate all further legal or constructive obligations for part or all of the benefits provided under a defined benefit plan, other than a payment of benefits to, or on behalf of, employees that is set out in the terms of the plan and included in the actuarial assumptions. [Refer: Net defined benefit liability (asset); Defined benefit plans [domain]; Actuarial assumptions [domain]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 19 -IssueDate 2024-01-01 -Paragraph 141 -Subparagraph d -URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=19&code=ifrs-tx-2024-en-r&anchor=para_141_d&doctype=Standard -URIDate 2024-03-27 + 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 2024-01-01 -Paragraph 141 -Subparagraph e -URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=19&code=ifrs-tx-2024-en-r&anchor=para_141_e&doctype=Standard -URIDate 2024-03-27 + 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 2024-01-01 -Paragraph 141 -Subparagraph b -URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=19&code=ifrs-tx-2024-en-r&anchor=para_141_b&doctype=Standard -URIDate 2024-03-27 + 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 [domain]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 19 -IssueDate 2024-01-01 -Paragraph 140 -Subparagraph a -URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=19&code=ifrs-tx-2024-en-r&anchor=para_140_a&doctype=Standard -URIDate 2024-03-27 + 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 [domain]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 19 -IssueDate 2024-01-01 -Paragraph 141 -Subparagraph g -URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=19&code=ifrs-tx-2024-en-r&anchor=para_141_g&doctype=Standard -URIDate 2024-03-27 + 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 2024-01-01 -Paragraph 147 -Subparagraph c -URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=19&code=ifrs-tx-2024-en-r&anchor=para_147_c&doctype=Standard -URIDate 2024-03-27 + Details
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- Definition Defined Benefit Pension And Other Post-Employment Benefit Plans + References No definition available. + Details
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