v3.26.1
ACCUMULATED OTHER COMPREHENSIVE INCOME (Details) - CAD ($)
$ in Millions
 12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Disclosure of analysis of other comprehensive income by item [line items]    
Balances, beginning of year $ 4,976.0 $ 4,302.6
Other comprehensive income (loss) 22.8 191.8
Balances, end of year 5,388.1 4,976.0
Foreign currency exchange differences on translation of foreign operations    
Disclosure of analysis of other comprehensive income by item [line items]    
Balances, beginning of year 417.7 174.5
Other comprehensive income (loss) (45.0) 243.2
Balances, end of year 372.7 417.7
Net change in cash flow hedges    
Disclosure of analysis of other comprehensive income by item [line items]    
Balances, beginning of year (34.6) (19.2)
Other comprehensive income (loss) 10.4 (15.4)
Balances, end of year (24.2) (34.6)
Net changes in financial assets carried at FVOCI    
Disclosure of analysis of other comprehensive income by item [line items]    
Balances, beginning of year (1.3) (1.3)
Other comprehensive income (loss) 0.0 0.0
Balances, end of year (1.3) (1.3)
Accumulated other comprehensive income    
Disclosure of analysis of other comprehensive income by item [line items]    
Balances, beginning of year 381.8 154.0
Other comprehensive income (loss) (34.6) 227.8
Other comprehensive loss (income) excluding cash flow hedges (34.6) 227.8
Balances, end of year $ 347.2 $ 381.8