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Retirement Benefit Plans - Additional Information (Detail) - CAD ($)
$ in Millions
12 Months Ended
Dec. 31, 2022
Dec. 31, 2021
Disclosure of net defined benefit liability (asset) [line items]    
Surplus plan, not recognized $ 390 $ 99
Defined contribution expense 61 $ 52
Defined Benefit Pension Plans    
Disclosure of net defined benefit liability (asset) [line items]    
Expected contribution to defined benefit pension plans for the next annual reporting period $ 24  
Weighted average duration of defined benefit obligation 13 years  
Non-Pension Post- Retirement Benefit Plans    
Disclosure of net defined benefit liability (asset) [line items]    
Weighted average duration of defined benefit obligation 13 years