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Accumulated change, net of tax, in accumulated gains and losses from derivative instruments designated and qualifying as the effective portion of cash flow hedges. Includes an entity's share of an equity investee's Increase or Decrease in deferred hedging gains or losses.

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The average strike price on the group of price risk option contracts such as put options or call options.

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

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Nominal mass used to calculate payments on a derivative instrument.

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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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Note 11 - Derivative Instruments (Details Textual) $ in Thousands, $ in Millions	3 Months Ended		12 Months Ended
	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Dec. 31, 2020 USD ($) oz $ / oz	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2020 CAD ($) $ / oz
Maximum Allocation of Forecasted CAD-demonimated Operating Costs			75.00%			75.00%
Forecasted CAD-denominated Operating Costs to be Hedged, Term (Year)			5 years
Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax, Ending Balance			$ 7,600
Foreign Currency Cash Flow Hedge Gain (Loss) Reclassified to Earnings, Net			2,700
Gain (Loss) on Components Excluded from Assessment of Foreign Currency Cash Flow Hedge Effectiveness			0
Derivative, Gain (Loss) on Derivative, Net, Total			(5,578)	$ (5,613)	$ 15,366
Derivative, Gain on Derivative					$ 8,100
Other Comprehensive Income (Loss) [Member]
Foreign Currency Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months			$ 3,100
Foreign Exchange Contract [Member] \| Casa Berardi [Member] \| Designated as Hedging Instrument [Member]
Derivative, Number of Instruments Held, Total			143			143
Derivative, Notional Amount			$ 223,000			$ 293.8
Foreign Exchange Contract [Member] \| Casa Berardi [Member] \| Designated as Hedging Instrument [Member] \| Minimum [Member]
Derivative, Forward Exchange Rate			1.2702			1.2702
Foreign Exchange Contract [Member] \| Casa Berardi [Member] \| Designated as Hedging Instrument [Member] \| Maximum [Member]
Derivative, Forward Exchange Rate			1.3785			1.3785
Silver Contracts [Member]
Derivative, Average Price Risk Option Strike Price (in USD per Ounce) \| $ / oz			16.50			16.50
Derivative, Nonmonetary Notional Amount, Mass (Ounce) \| oz			1,100,000
Gold Contracts [Member]
Derivative, Average Price Risk Option Strike Price (in USD per Ounce) \| $ / oz			1,650			1,650
Derivative, Nonmonetary Notional Amount, Mass (Ounce) \| oz			12,992
Unsettled Concentrate Sales Contracts [Member]
Derivative, Gain (Loss) on Derivative, Net, Total			$ (16,400)
Forecasted Future Concentrate Contracts [Member]
Derivative, Gain (Loss) on Derivative, Net, Total			(22,100)
Derivative, Gain on Derivative	$ 6,700	$ 32,800
Commodity Contract [Member]
Derivative Liability, Fair Value, Amount Not Offset Against Collateral, Total			12,200
Derivative, Fair Value, Obligations Under the Agreements			$ 12,200