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Pension and other post-retirement benefits - percentages of the total fair value of assets (Details) - Pension plans [member] - CAD ($) $ in Thousands | 12 Months Ended |
--- | --- | ---
Dec. 31, 2020 | Dec. 31, 2019
Disclosure of benefit plans [line items] |  |  |
The percentages of the total fair value of assets | [1] | 100.00% | 100.00%
Description of the refundable tax account held by CRA |  | equal to half of the sum of the realized investment income plus employer contributions less half of the benefits paid by the plan |
Related Parties [member] |  |  |
Disclosure of benefit plans [line items] |  |  |
Defined benefit plan assets |  | $ 0 | $ 0
Canadian Equity Securities [member] |  |  |
Disclosure of benefit plans [line items] |  |  |
The percentages of the total fair value of assets |  | 8.00% | 9.00%
US equity securities [Member] |  |  |
Disclosure of benefit plans [line items] |  |  |
The percentages of the total fair value of assets |  | 12.00% | 12.00%
Global Equity Securities [member] |  |  |
Disclosure of benefit plans [line items] |  |  |
The percentages of the total fair value of assets |  | 8.00% | 9.00%
Canadian Fixed Income [member] |  |  |
Disclosure of benefit plans [line items] |  |  |
The percentages of the total fair value of assets |  | 31.00% | 30.00%
Other [member] |  |  |
Disclosure of benefit plans [line items] |  |  |
The percentages of the total fair value of assets | [2] | 41.00% | 40.00%
[1] | The defined benefit plan assets contain no material amounts of related p arty assets at December 31, 2020 and 2019 respectively.
[2] | Relates mainly to the value of the refundable tax account held by the Canada Revenue Agency. The refundable total is approximately equal to half of the sum of the realized investment income plus employer contributions less half of the benefits paid by the plan .

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- Definition The description of the refundable tax account held by Canada Revenue Agency. + References No definition available. + Details
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- Definition Percentage of the total fair value of assets in the pension plans for each asset category. + References No definition available. + Details
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- Definition Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table. + References No definition available. + 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 2020-01-01 -Paragraph 140 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=19&code=ifrs-tx-2020-en-r&anchor=para_140_a&doctype=Standard -URIDate 2020-01-01 + Details
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