v3.26.1
Financial instruments (Schedule of fair value measurement) (Details) - USD ($)
$ in Millions
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
Disclosure of fair value measurement of assets [line items]      
Cash and cash equivalents $ 568.9 $ 541.8 $ 249.8
Short-term investments 0.0 40.0  
Deferred Copper Mountain acquisition consideration 14.4 0.0  
Wheaton refund liability 7.9 7.3  
Fair value [Member]      
Disclosure of fair value measurement of assets [line items]      
Cash and cash equivalents 568.9 541.8  
Short-term investments 0.0 40.0  
Collateral deposits 0.0 0.6  
Restricted cash 0.2 0.4  
Trade and other receivables 347.6 185.5  
Non-hedge derivative assets 0.6 14.3  
Investments at fair value through profit or loss 130.9 12.1  
Total financial assets 1,048.2 794.7  
Trade and other payables 330.5 255.2  
Deferred Copper Mountain acquisition consideration 17.5 0.0  
Contingent Copper Mountain acquisition consideration 14.1 0.0  
Agreements with communities 107.2 70.4  
Wheaton refund liability 13.9 9.9  
Senior unsecured notes 1,022.7 1,111.6  
Senior secured revolving credit facilities (2.3) (3.6)  
Non-hedge derivative liabilities 31.9 0.3  
Total financial liabilities 1,535.5 1,443.8  
Carrying value [Member]      
Disclosure of fair value measurement of assets [line items]      
Cash and cash equivalents 568.9 541.8  
Short-term investments 0.0 40.0  
Collateral deposits 0.0 0.6  
Restricted cash 0.2 0.4  
Trade and other receivables 347.6 185.5  
Non-hedge derivative assets 0.6 14.3  
Investments at fair value through profit or loss 130.9 12.1  
Total financial assets 1,048.2 794.7  
Trade and other payables 330.5 255.2  
Deferred Copper Mountain acquisition consideration 17.4 0.0  
Contingent Copper Mountain acquisition consideration 13.9 0.0  
Agreements with communities 105.9 68.4  
Wheaton refund liability 7.9 7.3  
Senior unsecured notes 1,010.9 1,111.1  
Senior secured revolving credit facilities (2.3) (3.6)  
Non-hedge derivative liabilities 31.9 0.3  
Total financial liabilities $ 1,516.1 $ 1,438.7