Income and mining taxes (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Non-capital losses [Member]
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Unused tax losses for which no deferred tax asset recognised	$ 30.0	$ 57.2
Non-capital losses [Member] \| United States [Member]
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Maximum taxable income limit percentage	80.00%
Capital losses [Member]
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Unused tax losses for which no deferred tax asset recognised	$ 130.2	158.7
Other [Member]
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Deductible temporary differences for which no deferred tax asset is recognised	561.6	651.3
Mining tax effect of temporary differences recognized [Member]
Disclosure of temporary difference, unused tax losses and unused tax credits [line items]
Deductible temporary differences for which no deferred tax asset is recognised	$ 8.8	$ 9.1