v3.25.4
Employee retirement benefits - Amounts Recorded in Consolidated Balance Sheet and Accumulated Other Comprehensive Income (Detail) - CAD ($)
$ in Millions
Dec. 31, 2025
Dec. 31, 2024
Schedule Of Defined Benefit Plans Disclosures [Line Items]    
Current liabilities $ (63) $ (61)
Other long-term obligations (811) (846)
Pension benefits    
Schedule Of Defined Benefit Plans Disclosures [Line Items]    
Other assets, including intangibles - net 1,035 853
Current liabilities (34) (33)
Other long-term obligations (375) (398)
Total recorded 626 422
Net actuarial loss (gain) 29 237
Prior service cost 346 373
Total recorded in accumulated other comprehensive income, before-tax 375 610
Other postretirement benefits    
Schedule Of Defined Benefit Plans Disclosures [Line Items]    
Other assets, including intangibles - net 0 0
Current liabilities (29) (28)
Other long-term obligations (436) (448)
Total recorded (465) (476)
Net actuarial loss (gain) (145) (110)
Prior service cost (73) (78)
Total recorded in accumulated other comprehensive income, before-tax $ (218) $ (188)