v3.26.1
EMPLOYEE BENEFITS OBLIGATIONS - Narrative (Details)
$ in Millions
 12 Months Ended
Mar. 31, 2026
CAD ($)
funded_defined_benefit_pension_plan
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Mar. 31, 2025
CAD ($)
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Disclosure of defined benefit plans [line items]    
Number of registered funded defined benefit pension plans | funded_defined_benefit_pension_plan 3  
Number of registered funded defined benefit pension plans for employees | funded_defined_benefit_pension_plan 2  
Number of registered funded defined benefit pension plans for designated executives | funded_defined_benefit_pension_plan 1  
Letters of credit outstanding $ 76.9 $ 63.9
Post-employment benefits – defined benefit plans (Note 21) $ (42.2) $ (37.4)
Number of common shares in the pension plan assets (in shares) | shares 0 0
Average duration of the defined benefit obligation (in years) 18 years 2 months 12 days  
Cost of sales    
Disclosure of defined benefit plans [line items]    
Post-employment benefits – defined benefit plans (Note 21) $ (23.0) $ (21.7)
Research and development expenses    
Disclosure of defined benefit plans [line items]    
Post-employment benefits – defined benefit plans (Note 21) (4.8) (5.1)
Selling, general and administrative expenses    
Disclosure of defined benefit plans [line items]    
Post-employment benefits – defined benefit plans (Note 21) (9.6) (10.3)
Restructuring, integration and acquisition costs    
Disclosure of defined benefit plans [line items]    
Post-employment benefits – defined benefit plans (Note 21) 0.0 0.4
Finance expense    
Disclosure of defined benefit plans [line items]    
Post-employment benefits – defined benefit plans (Note 21) (4.8) (0.7)
Capitalized pension costs    
Disclosure of defined benefit plans [line items]    
Post-employment benefits – defined benefit plans (Note 21) $ (2.3) $ (2.8)