v3.26.1
Financial instruments (Narrative) (Details)
lb in Millions, $ in Millions
Dec. 31, 2025
USD ($)
lb
oz
$ / OZ
$ / lbs
Dec. 31, 2024
USD ($)
lb
$ / lbs
Disclosure of detailed information about financial instruments [line items]    
Deposits and other investments with Schedule 1 Canadian banks, as a percentage of total cash and cash equivalents 92.00% 87.00%
Percentage of entity's trade receivables that are insured 43.00% 36.00%
Copper fixed for floating swaps [Member]    
Disclosure of detailed information about financial instruments [line items]    
Pounds of copper fixed for floating swaps | lb 57.9 61.7
Average price recorded for copper fixed for floating swaps | $ / lbs 5.18 4.19
Derivative financial assets   $ 13.7
Derivative financial liabilities $ 26.4  
Gold fixed for floating swaps [Member]    
Disclosure of detailed information about financial instruments [line items]    
Ounces of net gold swaps outstanding | oz 23,180  
Average price recorded for gold fixed for floating swaps | $ / OZ 4,333  
Derivative financial liabilities $ 4.9  
Zinc fixed for floating swaps [Member]    
Disclosure of detailed information about financial instruments [line items]    
Pounds of zinc fixed for floating swaps | lb 7.3 9.7
Average price recorded for zinc fixed for floating swaps | $ / lbs 1.4 1.38
Derivative financial assets $ 0.0 $ 0.3
Copper forward sale [Member]    
Disclosure of detailed information about financial instruments [line items]    
Pounds of copper forwards outstanding | lb 0.0 5.3
Average price recorded for copper forwards outstanding | $ / lbs   3.95
Derivative financial liabilities $ 0.0 $ 0.1
Copper costless collars [Member]    
Disclosure of detailed information about financial instruments [line items]    
Pounds of copper collars outstanding | lb 0.0 6.6
Average floor price | $ / lbs   3.88
Average cap price | $ / lbs   4.14
Derivative financial assets $ 0.0 $ 0.1
Provisional pricing - copper and zinc [Member]    
Disclosure of detailed information about financial instruments [line items]    
Derivative financial assets $ 40.9  
Derivative financial liabilities   $ 13.9
Customer 1 [Member]    
Disclosure of detailed information about financial instruments [line items]    
Percentage of receivables that represent largest customers 23.00% 39.00%
Customer 2 [Member]    
Disclosure of detailed information about financial instruments [line items]    
Percentage of receivables that represent largest customers 21.00% 28.00%