POST-EMPLOYMENT BENEFITS - Remeasurement Recognized in OCI and Equity (Details) - CAD ($) $ in Millions	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022
Disclosure of net defined benefit liability (asset) [line items]
Return (loss) on plan assets (excluding interest income)	$ 281	$ (499)
Change in asset ceiling	40	(33)
Domestic defined benefit plans
Disclosure of net defined benefit liability (asset) [line items]
Return (loss) on plan assets (excluding interest income)	149	(604)
Change in financial assumptions	(328)	942
Change in demographic assumptions	(8)	0
Effect of experience adjustments	(44)	(36)
Remeasurement (loss) gain, recognized in other comprehensive income and equity	$ (191)	$ 269

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)]

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

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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

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- Definition

The decrease (increase) in a net defined benefit liability (asset) resulting from actuarial gains (losses) arising from experience adjustments that result in remeasurements of the net defined benefit liability (asset). Experience adjustments deal with the effects of differences between the previous actuarial assumptions and what has actually occurred. [Refer: Net defined benefit liability (asset)]

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 19
-IssueDate 2023-01-01
-Paragraph 141
-Subparagraph c
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=19&code=ifrs-tx-2023-en-r&anchor=para_141_c&doctype=Standard
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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.

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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

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- Definition

The decrease (increase) in a net defined benefit liability (asset) resulting from the remeasurement of that net defined benefit liability (asset). [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
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=19&code=ifrs-tx-2023-en-r&anchor=para_141_c&doctype=Standard
-URIDate 2023-03-23

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- Definition

The decrease (increase) in the net defined benefit liability (asset) resulting from the return on plan assets, excluding amounts included in interest income or expense. The return on plan assets is interest, dividends and other revenue derived from the plan assets, together with realised and unrealised gains or losses on the plan assets, less any costs of managing plan assets and less any tax payable by the plan itself, other than tax included in the actuarial assumptions used to measure the present value of the defined benefit obligation. [Refer: Plan assets [member]; Net defined benefit liability (asset); Actuarial assumptions [member]; 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 i
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=19&code=ifrs-tx-2023-en-r&anchor=para_141_c_i&doctype=Standard
-URIDate 2023-03-23

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