v3.25.4
SHORT-TERM BORROWINGS - Movement in Borrowing Programs (Details)
$ in Millions
 12 Months Ended
Dec. 31, 2025
CAD ($)
$ / $
Dec. 31, 2025
USD ($)
$ / $
Dec. 31, 2024
CAD ($)
$ / $
Dec. 31, 2024
USD ($)
$ / $
Disclosure of detailed information about borrowings [line items]        
Short-term borrowings, beginning balance $ 2,959,000,000      
Net (repayment of) proceeds received from short-term borrowings 1,021,000,000   $ 1,138,000,000  
Loss (gain) on foreign exchange (45,000,000)   222,000,000  
Short-term borrowings, ending balance 4,000,000,000   2,959,000,000  
US commercial paper program        
Disclosure of detailed information about borrowings [line items]        
Short-term borrowings, beginning balance $ 452,000,000 $ 314 $ 150,000,000 $ 113
Exchange rate on short-term borrowings | $ / $ 1.439 1.439 1.327 1.327
Net (repayment of) proceeds received from short-term borrowings $ (451,000,000) $ (318) $ 265,000,000 $ 190
Exchange rate on (repayment of) proceeds received from short-term borrowings 1.418 1.418 1.395 1.395
Discount on issuance $ 6,000,000 $ 4 $ 15,000,000 $ 11
Exchange rate on discounts on issuance of short-term borrowings | $ / $     1.364 1.364
Loss (gain) on foreign exchange (7,000,000)   $ 22,000,000  
Short-term borrowings, ending balance $ 0 $ 0 $ 452,000,000 $ 314
Exchange rate on short-term borrowings | $ / $ 0 0 1.439 1.439
Non-revolving credit facility borrowings (net of the discount on issuance)        
Disclosure of detailed information about borrowings [line items]        
Short-term borrowings, beginning balance $ 507,000,000   $ 0  
Net (repayment of) proceeds received from short-term borrowings 1,472,000,000   473,000,000  
Loss (gain) on foreign exchange 21,000,000   34,000,000  
Short-term borrowings, ending balance $ 2,000,000,000   $ 507,000,000