v3.26.1
Income taxes (Significant components of deferred tax assets and liabilities) (Details) - CAD ($)
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]      
Net deferred tax asset, recognized in earnings $ (176,962,000) $ (51,296,000)  
Deferred tax assets 666,457,000 843,131,000  
Deferred tax liabilities 0 0  
Net deferred tax asset (liability) 666,457,000 843,131,000 $ 892,860,000
Property, plant and equipment [Member]      
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]      
Net deferred tax asset, recognized in earnings (158,359,000) (41,454,000)  
Net deferred tax assets 316,516,000 475,008,000  
Provision for reclamation [Member]      
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]      
Net deferred tax asset, recognized in earnings (4,247,000) (11,237,000)  
Net deferred tax assets 184,175,000 188,422,000  
Inventories [Member]      
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]      
Net deferred tax asset, recognized in earnings (976,000) (4,979,000)  
Net deferred tax assets 5,584,000 6,561,000  
Net deferred tax liabilities 0 0  
Foreign exploration and development [Member]      
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]      
Net deferred tax asset, recognized in earnings (267,000) (398,000)  
Net deferred tax assets 1,924,000 2,191,000  
Income tax losses (gains) [Member]      
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]      
Net deferred tax asset, recognized in earnings 12,080,000 (8,108,000)  
Net deferred tax assets 97,749,000 85,668,000  
Defined benefit plan actuarial losses [Member]      
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]      
Net deferred tax asset, recognized in earnings 0 0  
Net deferred tax assets 5,664,000 5,233,000  
Long-term investments and other, deferred tax assets [Member]      
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]      
Net deferred tax asset, recognized in earnings (25,193,000) 14,880,000  
Net deferred tax assets 54,845,000 80,048,000  
Deferred tax assets [Member]      
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]      
Net deferred tax asset, recognized in earnings (176,962,000) (51,296,000)  
Net deferred tax assets 666,457,000 843,131,000  
Property, plant and equipment [Member]      
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]      
Net deferred tax asset, recognized in earnings 0 0  
Net deferred tax liabilities 0 0  
Inventories [Member]      
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]      
Net deferred tax asset, recognized in earnings 0 0  
Net deferred tax liabilities 0 0  
Deferred tax liabilities [Member]      
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]      
Net deferred tax asset, recognized in earnings 0 0  
Net deferred tax liabilities $ 0 $ 0