v3.26.1
EMPLOYEE BENEFITS OBLIGATIONS - Expected Employer Contributions (Details)
$ in Millions
 12 Months Ended
Mar. 31, 2026
CAD ($)
Expected employer contributions in funded plans  
Disclosure of defined benefit plans [line items]  
Expected employer contributions and expected benefits paid $ 24.2
Expected benefits paid in unfunded plans  
Disclosure of defined benefit plans [line items]  
Expected employer contributions and expected benefits paid 4.1
Canadian | Expected employer contributions in funded plans  
Disclosure of defined benefit plans [line items]  
Expected employer contributions and expected benefits paid 24.2
Canadian | Expected benefits paid in unfunded plans  
Disclosure of defined benefit plans [line items]  
Expected employer contributions and expected benefits paid 3.3
Foreign | Expected employer contributions in funded plans  
Disclosure of defined benefit plans [line items]  
Expected employer contributions and expected benefits paid 0.0
Foreign | Expected benefits paid in unfunded plans  
Disclosure of defined benefit plans [line items]  
Expected employer contributions and expected benefits paid $ 0.8