v3.26.3
ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Details) - CAD ($)
$ in Millions
 9 Months Ended
Sep. 30, 2026
Sep. 30, 2025
Disclosure of accumulated other comprehensive income loss [line items]    
Beginning balance $ 401 $ 2,313
Other Comprehensive Income (Loss), Before Tax 508 (433)
Reclassification on Divestiture (Note 8)   (1,261)
Income Tax (Expense) Recovery   0
Ending balance 909 619
Pension and Other Post-Employment Benefits    
Disclosure of accumulated other comprehensive income loss [line items]    
Beginning balance 86 69
Other Comprehensive Income (Loss), Before Tax 2 13
Reclassification on Divestiture (Note 8)   0
Income Tax (Expense) Recovery   (3)
Ending balance 88 79
Private Equity Investments    
Disclosure of accumulated other comprehensive income loss [line items]    
Beginning balance 131 156
Other Comprehensive Income (Loss), Before Tax 3 (26)
Reclassification on Divestiture (Note 8)   0
Income Tax (Expense) Recovery   3
Ending balance 134 133
Foreign Currency Translation Adjustment    
Disclosure of accumulated other comprehensive income loss [line items]    
Beginning balance 184 2,088
Other Comprehensive Income (Loss), Before Tax 503 (420)
Reclassification on Divestiture (Note 8)   (1,261)
Income Tax (Expense) Recovery   0
Ending balance $ 687 $ 407