v3.26.1
Pension and other benefits - Net Periodic Benefit Cost for DB Pension Plans and Other Benefits (Details) - CAD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Defined Benefit Plan and Other Postretirement Benefit Plans        
Current service cost $ 22 $ 25 $ 44 $ 49
Other components of net periodic benefit (recovery) cost:        
Interest cost on benefit obligation 124 122 247 244
Expected return on plan assets (234) (231) (468) (463)
Recognized net actuarial (gain) loss (1) 1 (2) 3
Amortization of prior service costs 1 1 3 2
Total other components of net periodic benefit (recovery) cost (110) (107) (220) (214)
Net periodic benefit (recovery) cost (88) (82) (176) (165)
Pensions        
Defined Benefit Plan and Other Postretirement Benefit Plans        
Current service cost 19 21 38 42
Other components of net periodic benefit (recovery) cost:        
Interest cost on benefit obligation 118 116 236 233
Expected return on plan assets (234) (231) (468) (463)
Recognized net actuarial (gain) loss (1) 2 (2) 4
Amortization of prior service costs 1 1 3 2
Total other components of net periodic benefit (recovery) cost (116) (112) (231) (224)
Net periodic benefit (recovery) cost (97) (91) (193) (182)
Other benefits        
Defined Benefit Plan and Other Postretirement Benefit Plans        
Current service cost 3 4 6 7
Other components of net periodic benefit (recovery) cost:        
Interest cost on benefit obligation 6 6 11 11
Expected return on plan assets 0 0 0 0
Recognized net actuarial (gain) loss 0 (1) 0 (1)
Amortization of prior service costs 0 0 0 0
Total other components of net periodic benefit (recovery) cost 6 5 11 10
Net periodic benefit (recovery) cost $ 9 $ 9 $ 17 $ 17