v3.26.1
EMPLOYEE BENEFITS OBLIGATIONS - Plan Assets (Details) - CAD ($)
$ in Millions
Mar. 31, 2026
Mar. 31, 2025
Disclosure of fair value of plan assets [line items]    
Plan assets $ 635.8 $ 585.9
Canadian plans    
Disclosure of fair value of plan assets [line items]    
Private and property investments 147.8 151.6
Cash and cash equivalents 7.2 14.6
Other 18.9 12.1
Plan assets 628.3 578.3
Foreign plans    
Disclosure of fair value of plan assets [line items]    
Equity funds 0.4 0.4
Other 0.3 0.3
Plan assets 7.5 7.6
Government | Canadian plans    
Disclosure of fair value of plan assets [line items]    
Bond funds 152.1 135.3
Corporate | Canadian plans    
Disclosure of fair value of plan assets [line items]    
Bond funds 62.8 63.4
Corporate | Foreign plans    
Disclosure of fair value of plan assets [line items]    
Bond funds 6.8 6.9
Quoted    
Disclosure of fair value of plan assets [line items]    
Plan assets 7.2 7.3
Quoted | Canadian plans    
Disclosure of fair value of plan assets [line items]    
Private and property investments 0.0 0.0
Cash and cash equivalents 0.0 0.0
Other 0.0 0.0
Plan assets 0.0 0.0
Quoted | Foreign plans    
Disclosure of fair value of plan assets [line items]    
Equity funds 0.4 0.4
Other 0.0 0.0
Plan assets 7.2 7.3
Quoted | Government | Canadian plans    
Disclosure of fair value of plan assets [line items]    
Bond funds 0.0 0.0
Quoted | Corporate | Canadian plans    
Disclosure of fair value of plan assets [line items]    
Bond funds 0.0 0.0
Quoted | Corporate | Foreign plans    
Disclosure of fair value of plan assets [line items]    
Bond funds 6.8 6.9
Unquoted    
Disclosure of fair value of plan assets [line items]    
Plan assets 628.6 578.6
Unquoted | Canadian plans    
Disclosure of fair value of plan assets [line items]    
Private and property investments 147.8 151.6
Cash and cash equivalents 7.2 14.6
Other 18.9 12.1
Plan assets 628.3 578.3
Unquoted | Foreign plans    
Disclosure of fair value of plan assets [line items]    
Equity funds 0.0 0.0
Other 0.3 0.3
Plan assets 0.3 0.3
Unquoted | Government | Canadian plans    
Disclosure of fair value of plan assets [line items]    
Bond funds 152.1 135.3
Unquoted | Corporate | Canadian plans    
Disclosure of fair value of plan assets [line items]    
Bond funds 62.8 63.4
Unquoted | Corporate | Foreign plans    
Disclosure of fair value of plan assets [line items]    
Bond funds 0.0 0.0
Canadian | Canadian plans    
Disclosure of fair value of plan assets [line items]    
Equity funds 52.6 43.5
Canadian | Quoted | Canadian plans    
Disclosure of fair value of plan assets [line items]    
Equity funds 0.0 0.0
Canadian | Unquoted | Canadian plans    
Disclosure of fair value of plan assets [line items]    
Equity funds 52.6 43.5
Foreign | Canadian plans    
Disclosure of fair value of plan assets [line items]    
Equity funds 186.9 157.8
Foreign | Quoted | Canadian plans    
Disclosure of fair value of plan assets [line items]    
Equity funds 0.0 0.0
Foreign | Unquoted | Canadian plans    
Disclosure of fair value of plan assets [line items]    
Equity funds $ 186.9 $ 157.8