v3.25.4
STOCK-BASED COMPENSATION - Additional Information (Details)
 12 Months Ended
Dec. 31, 2025
CAD ($)
plan
$ / shares
shares
Dec. 31, 2024
CAD ($)
$ / shares
shares
Dec. 31, 2015
CAD ($)
$ / shares
shares
Sep. 01, 2015
Apr. 01, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Number of plans | plan 2        
Closing share price of common shares (in dollars per share) | $ / shares $ 54.64 $ 54.64      
Grant date total fair value of awards $ 16,000,000 $ 14,000,000      
Management Employee Share Ownership Plans          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Highest percentage of participant's salary towards purchasing common shares     6.00%    
Lowest percentage of participant's salary towards purchasing common shares     1.00%    
Employer matching contribution, percent of match     50.00%    
Maximum amount contributed by employer     $ 25,000    
Society Employee Share Ownership Plans          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Highest percentage of participant's salary towards purchasing common shares     4.00%    
Lowest percentage of participant's salary towards purchasing common shares     1.00%    
Employer matching contribution, percent of match     25.00%    
PWU Employee Share Ownership Plan          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Highest percentage of participant's salary towards purchasing common shares 4.00%        
Lowest percentage of participant's salary towards purchasing common shares 1.00%        
Employer matching contribution, percent of match 33.00%        
Employee Share Ownership Plan (ESOP)          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Contribution under the plan $ 9,000,000 $ 5,000,000      
PWU Share Grant Plan          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Highest percentage of participant's salary towards purchasing common shares         2.70%
Weighted-average exercise price (in dollars per share) | $ / shares $ 20.50        
Shares granted (in shares) | shares     3,979,062    
Society Share Grant Plan          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Highest percentage of participant's salary towards purchasing common shares       2.00%  
Weighted-average exercise price (in dollars per share) | $ / shares $ 20.50        
Shares granted (in shares) | shares     1,433,292    
Share Grant Plans          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Weighted-average exercise price (in dollars per share) | $ / shares   $ 0 $ 20.50    
Shares granted (in shares) | shares   1,092      
Fair value of shares granted     $ 111,000,000    
Vested and issued (in shares) | shares 335,669 348,678      
Compensation expenses $ 1,000,000 $ 2,000,000      
Directors' Deferred Share Units Plan          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
DSU value equivalent to common shares (in shares) | shares 1        
Directors' Deferred Share Units Plan | Deferred Share Units          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Compensation expenses $ 2,000,000 1,000,000      
Liability related to share based compensation $ 6,000,000 5,000,000      
Management Deferred Share Units Plan          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
DSU value equivalent to common shares (in shares) | shares 1        
Management Deferred Share Units Plan | Deferred Share Units          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Compensation expenses $ 2,000,000 1,000,000      
Liability related to share based compensation $ 4,000,000 4,000,000      
Long Term Incentive Plan          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Aggregate number of common shares issuable under the plan (in shares) | shares 11,900,000        
Compensation expenses $ 11,000,000 $ 10,000,000      
Maximum | PWU Share Grant Plan          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Requisite service period (in years) 35 years        
Aggregate number of common shares issuable under the plan (in shares) | shares 3,981,763        
Maximum | Society Share Grant Plan          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Requisite service period (in years) 35 years        
Aggregate number of common shares issuable under the plan (in shares) | shares 1,434,686