Pension and other post-retirement benefits (Defined benefit plans) (Details) - CAD ($) $ in Thousands	12 Months Ended
Dec. 31, 2024	Dec. 31, 2023
Actuarial loss (gain) arising from:
Administrative costs paid	$ 253,150	$ 245,539
Domestic Defined benefit plans [Member]
Disclosure of fair value of plan [line items]
Current service cost	2,008	1,567
Interest (income) cost	2,469	2,326
Return on assets excluding interest income	(95)	(18)
Actuarial loss (gain) arising from:
Past service cost	0	0
Domestic Defined benefit plans [Member] \| Plan Assets [Member]
Disclosure of fair value of plan [line items]
Fair value of plan assets, beginning of year	3,717	4,402
Interest (income) cost	(150)	(201)
Return on assets excluding interest income	95	18
Employer contributions	943	0
Actuarial loss (gain) arising from:
Benefits paid	(911)	(901)
Administrative costs paid	(3)	(3)
Fair value of plan assets, end of year	3,991	3,717
Domestic Defined benefit plans [Member] \| Defined Benefit Obligations [Member]
Disclosure of fair value of plan [line items]
Defined benefit obligation, beginning of year	60,038	51,218
Current service cost	2,008	1,567
Interest (income) cost	2,619	2,527
Actuarial loss (gain) arising from:
financial assumptions	(909)	4,784
experience adjustment	4,242	1,559
Past service cost	0	0
Benefits paid	(10,972)	(1,704)
Foreign exchange	339	87
Defined benefit obligation, end of year	57,365	60,038
Defined benefit liability [note 15]	(53,374)	(56,321)
Other Benefit Plans [Member]
Disclosure of fair value of plan [line items]
Current service cost	849	689
Interest (income) cost	948	987
Return on assets excluding interest income	0	0
Actuarial loss (gain) arising from:
Past service cost	4,652	0
Other Benefit Plans [Member] \| Plan Assets [Member]
Disclosure of fair value of plan [line items]
Fair value of plan assets, beginning of year	0	0
Interest (income) cost	0	0
Return on assets excluding interest income	0	0
Employer contributions	0	0
Actuarial loss (gain) arising from:
Benefits paid	0	0
Administrative costs paid	0	0
Fair value of plan assets, end of year	0	0
Other Benefit Plans [Member] \| Defined Benefit Obligations [Member]
Disclosure of fair value of plan [line items]
Defined benefit obligation, beginning of year	20,681	19,364
Current service cost	849	689
Interest (income) cost	948	987
Actuarial loss (gain) arising from:
financial assumptions	0	443
experience adjustment	7	18
Past service cost	4,652	0
Benefits paid	(1,837)	(820)
Foreign exchange	0	0
Defined benefit obligation, end of year	25,300	20,681
Defined benefit liability [note 15]	$ (25,300)	$ (20,681)

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)]

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