The amount of required settlement obligation under the agreements at termination.

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Period within which forecasted CAD (Canadian dollar) denominated operating costs will be hedged.

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Represents the maximum percentage of CAD (Canadian dollar) denominated operating costs to be hedged in the future.

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Amount, after tax, of accumulated gain (loss) on derivative instrument designated and qualifying as cash flow hedge included in assessment of hedge effectiveness.

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Fair value, after offset of derivative asset, of financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, elected not to be and before offset against a right to receive collateral under a master netting arrangement. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

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Contractual rate at which a foreign currency can be purchased or sold.

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Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

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Nominal or face amount used to calculate payment on derivative.

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The number of derivative instruments of a particular group held by the entity.

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The amount of net gains or losses on foreign currency cash flow hedges reclassified during the period to earnings from accumulated other comprehensive income upon the hedged transaction affecting earnings.

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The estimated net amount of unrealized gains or losses on foreign currency cash flow hedges at the reporting date expected to be reclassified to earnings within the next 12 months.

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The net gain (loss) relating to components of the gain (loss) on foreign currency cash flow hedging instruments excluded from the assessment of hedge effectiveness. Recognized in earnings.

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Note 9 - Derivative Instruments (Details Textual) $ in Thousands, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2021 CAD ($)
Maximum Allocation of Forecasted CAD-demonimated Operating Costs	75.00%		75.00%		75.00%
Forecasted CAD-denominated Operating Costs to be Hedged, Term (Year)			5 years
AOCI, Cash Flow Hedge, Cumulative Gain (Loss), after Tax	$ 4,800		$ 4,800
Foreign Currency Cash Flow Hedge Gain (Loss) Reclassified to Earnings, Net			3,500
Gain (Loss) on Components Excluded from Assessment of Foreign Currency Cash Flow Hedge Effectiveness			0
Derivative, Gain (Loss) on Derivative, Net, Total			13,937	$ (4,483)
Other Comprehensive Income (Loss) [Member]
Foreign Currency Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months	$ 2,700		$ 2,700
Foreign Exchange Contract [Member] \| Casa Berardi [Member] \| Designated as Hedging Instrument [Member]
Derivative, Number of Instruments Held, Total	73		73		73
Derivative, Notional Amount	$ 187,700		$ 187,700		$ 245.6
Foreign Exchange Contract [Member] \| Casa Berardi [Member] \| Designated as Hedging Instrument [Member] \| Minimum [Member]
Derivative, Forward Exchange Rate	1.2702		1.2702		1.2702
Foreign Exchange Contract [Member] \| Casa Berardi [Member] \| Designated as Hedging Instrument [Member] \| Maximum [Member]
Derivative, Forward Exchange Rate	1.3753		1.3753		1.3753
Unsettled Concentrate Sales Contracts [Member]
Derivative, Gain (Loss) on Derivative, Net, Total	$ 5,000	$ 9,600	$ 4,500	12,900
Forecasted Future Concentrate Contracts [Member]
Derivative, Gain (Loss) on Derivative, Net, Total	12,100	$ 6,700	4,700	$ 12,800
Commodity Contract [Member]
Derivative Liability, Fair Value, Amount Not Offset Against Collateral, Total	9,300		9,300
Derivative, Fair Value, Obligations Under the Agreements	$ 9,300		$ 9,300