XML 171 R137.htm IDEA: XBRL DOCUMENT v3.22.0.1
Employee Future Benefits - Summary of Amounts Recognized in Consolidated Statements of Financial Position (Detail) - CAD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Pension defined benefit plans [member]    
Disclosure of defined benefit plans [Line Items]    
Defined benefit obligation $ 4,560 $ 4,901
Fair value of plan assets 4,510 4,595
Deficit 50 306
Effect of asset limit 37  
Deficit and net defined benefit liability 87 306
Pension defined benefit plans [member] | Funded [Member]    
Disclosure of defined benefit plans [Line Items]    
Deficit and net defined benefit liability (600) (446)
Pension defined benefit plans [member] | Unfunded [Member]    
Disclosure of defined benefit plans [Line Items]    
Deficit and net defined benefit liability 687 752
Retiree welfare plans [Member]    
Disclosure of defined benefit plans [Line Items]    
Defined benefit obligation 584 638
Fair value of plan assets 587 606
Deficit (3) 32
Deficit and net defined benefit liability (3) 32
Retiree welfare plans [Member] | Funded [Member]    
Disclosure of defined benefit plans [Line Items]    
Deficit and net defined benefit liability (154) (134)
Retiree welfare plans [Member] | Unfunded [Member]    
Disclosure of defined benefit plans [Line Items]    
Deficit and net defined benefit liability $ 151 $ 166