v3.26.1
DEBT FACILITIES - Long-term Debt (Details)
$ in Millions, $ in Millions
Mar. 31, 2026
CAD ($)
Mar. 31, 2026
USD ($)
Mar. 31, 2025
CAD ($)
Disclosure of detailed information about borrowings [line items]      
Current $ 252.0   $ 399.0
Non-current 2,982.2   3,071.4
U.S. dollar, fixed rate - 3.60% to 4.90%      
Disclosure of detailed information about borrowings [line items]      
Notional amount   $ 778.0  
Current 102.0   20.0
Non-current $ 978.7   1,114.7
U.S. dollar, fixed rate - 3.60% to 4.90% | Bottom of range      
Disclosure of detailed information about borrowings [line items]      
Interest rate (in percent) 3.60% 3.60%  
U.S. dollar, fixed rate - 3.60% to 4.90% | Top of range      
Disclosure of detailed information about borrowings [line items]      
Interest rate (in percent) 4.90% 4.90%  
Canadian dollar, Series 1, fixed rate - 5.54%      
Disclosure of detailed information about borrowings [line items]      
Interest rate (in percent) 5.54% 5.54%  
Notional amount $ 400.0    
Current 0.0   0.0
Non-current $ 398.7   398.1
Canadian dollar, fixed rate - 4.15%      
Disclosure of detailed information about borrowings [line items]      
Interest rate (in percent) 4.15% 4.15%  
Notional amount $ 5.7    
Current 2.9   2.9
Non-current 2.8   5.7
U.S. dollar, variable rate      
Disclosure of detailed information about borrowings [line items]      
Notional amount   $ 47.7  
Current 4.1   178.7
Non-current 61.9   288.3
Canadian dollar, variable rate      
Disclosure of detailed information about borrowings [line items]      
Notional amount 285.9    
Current 5.6   5.6
Non-current 280.4   12.6
Other      
Disclosure of detailed information about borrowings [line items]      
Current 0.0   33.5
Non-current 0.0   0.0
U.S. dollar      
Disclosure of detailed information about borrowings [line items]      
Current 42.3   92.0
Non-current 433.3   432.0
Other      
Disclosure of detailed information about borrowings [line items]      
Current 25.9   29.1
Non-current 260.7   239.0
Canadian dollar      
Disclosure of detailed information about borrowings [line items]      
Current 69.2   37.2
Non-current 565.7   581.0
U.S. dollar, variable rate      
Disclosure of detailed information about borrowings [line items]      
Current 0.0   0.0
Non-current 0.0   0.0
Canadian dollar, variable rate      
Disclosure of detailed information about borrowings [line items]      
Current 0.0   0.0
Non-current $ 0.0   $ 0.0