v3.25.4
RELATED PARTY TRANSACTIONS - Narrative (Details) - CAD ($)
$ in Millions
 12 Months Ended
Apr. 03, 2023
Dec. 31, 2025
Dec. 31, 2024
Disclosure of transactions between related parties [line items]      
Key management personnel compensation, amount paid   $ 49 $ 56
Amount recognized in net income and paid during the year   $ 3 10
Related party transaction, payment period   1 month  
Shaw Communications Inc.      
Disclosure of transactions between related parties [line items]      
Liability assumed through business combination related to a special arrangement $ 102    
Key management personnel compensation, monthly amount 1    
Key management personnel compensation, amount paid   $ 12 12
Key management personnel compensation, remaining liability   83  
Controlling Shareholder      
Disclosure of transactions between related parties [line items]      
Related party transaction (less than)   1 1
Key management personnel of entity or parent      
Disclosure of transactions between related parties [line items]      
Accounts payable and other liabilities $ 20    
Period following closing 2 years    
Total for all associates      
Disclosure of transactions between related parties [line items]      
Cash repayments of advances and loans from related parties   $ 1 $ 1