v3.25.4
FINANCIAL RISK MANAGEMENT AND FINANCIAL INSTRUMENTS - Credit Risk (Details) - CAD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
Disclosure of financial assets that are either past due or impaired [line items]      
Contract assets $ 253 $ 268 $ 276
Total customer accounts receivable and contract assets 6,318 5,804  
Trade Receivables and Contract Assets | Allowance for doubtful accounts      
Disclosure of financial assets that are either past due or impaired [line items]      
Financial assets 259 227 $ 213
Reconciliation of changes in allowance account for credit losses of financial assets [abstract]      
Balance, beginning of year 227 213  
Allowance for doubtful accounts expense 327 259  
Acquired in business combination 8 0  
Net use (303) (245)  
Balance, end of year 259 227  
Accounts receivable      
Disclosure of financial assets that are either past due or impaired [line items]      
Financial assets 6,065 5,536  
Reconciliation of changes in allowance account for credit losses of financial assets [abstract]      
Balance, beginning of year 5,536    
Balance, end of year 6,065 5,536  
Accounts receivable | Unbilled financing receivables      
Disclosure of financial assets that are either past due or impaired [line items]      
Financial assets 3,646 3,530  
Reconciliation of changes in allowance account for credit losses of financial assets [abstract]      
Balance, beginning of year 3,530    
Balance, end of year 3,646 3,530  
Accounts receivable | Less than 30 days past billing date      
Disclosure of financial assets that are either past due or impaired [line items]      
Financial assets 1,748 1,419  
Reconciliation of changes in allowance account for credit losses of financial assets [abstract]      
Balance, beginning of year 1,419    
Balance, end of year 1,748 1,419  
Accounts receivable | 30-60 days past billing date      
Disclosure of financial assets that are either past due or impaired [line items]      
Financial assets 351 334  
Reconciliation of changes in allowance account for credit losses of financial assets [abstract]      
Balance, beginning of year 334    
Balance, end of year 351 334  
Accounts receivable | 61-90 days past billing date      
Disclosure of financial assets that are either past due or impaired [line items]      
Financial assets 152 122  
Reconciliation of changes in allowance account for credit losses of financial assets [abstract]      
Balance, beginning of year 122    
Balance, end of year 152 122  
Accounts receivable | Greater than 90 days past billing date      
Disclosure of financial assets that are either past due or impaired [line items]      
Financial assets 168 131  
Reconciliation of changes in allowance account for credit losses of financial assets [abstract]      
Balance, beginning of year 131    
Balance, end of year 168 131  
Accounts receivable | Gross carrying amount      
Disclosure of financial assets that are either past due or impaired [line items]      
Financial assets 772 687  
Reconciliation of changes in allowance account for credit losses of financial assets [abstract]      
Balance, beginning of year 687    
Balance, end of year 772 687  
Accounts receivable | Allowance for doubtful accounts      
Disclosure of financial assets that are either past due or impaired [line items]      
Financial assets 258 226  
Reconciliation of changes in allowance account for credit losses of financial assets [abstract]      
Balance, beginning of year 226    
Balance, end of year 258 226  
Contract assets      
Disclosure of financial assets that are either past due or impaired [line items]      
Contract assets 253 268  
Contract assets | Allowance for doubtful accounts      
Disclosure of financial assets that are either past due or impaired [line items]      
Contract assets $ 1 $ 1