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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Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

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-Publisher SEC
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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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Fair value, after the effects of master netting arrangements, of a financial asset or other 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, expected to be settled within one year or normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset.

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Fair value, after the effects of master netting arrangements, of a financial asset or other 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, expected to be settled after one year or the normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset.

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

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Fair value, after the effects of master netting arrangements, of a 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, expected to be settled within one year or normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset.

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Fair value, after the effects of master netting arrangements, of a 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, expected to be settled after one year or the normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset.

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

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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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The difference between the book value and the sale price of options, swaps, futures, forward contracts, and other derivative instruments. This element refers to the gain (loss) included in earnings.

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Note 11 - Derivative Instruments (Details Textual) $ in Thousands, $ in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2018 CAD ($)	Jun. 30, 2018 MXN ($)
Maximum Allocation of Forecasted CAD-demonimated Operating Costs	75.00%		75.00%		75.00%	75.00%
Forecasted CAD-denominated Operating Costs to be Hedged, Term			5 years
Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax, Ending Balance	$ 2,200		$ 2,200
Gain (Loss) on Sale of Derivatives	16,804	$ 2,487	20,811	$ (5,322)
Gain (Loss) on Components Excluded from Assessment of Foreign Currency Cash Flow Hedge Effectiveness			10
Derivative, Gain on Derivative	2,700	$ 800	3,300
Derivative Liability, Fair Value, Amount Not Offset Against Collateral, Total	3,700		3,700
Derivative, Fair Value, Obligations Under the Agreements	3,700		3,700
Cost of Sales [Member]
Gain (Loss) on Sale of Derivatives			400
Other Comprehensive Income (Loss) [Member]
Foreign Currency Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months	1,300		1,300
Foreign Exchange Contract [Member] \| Other Current Assets [Member]
Derivative Asset, Current	100		100
Foreign Exchange Contract [Member] \| Other Noncurrent Assets [Member]
Derivative Assets, Noncurrent, Total	100		100
Foreign Exchange Contract [Member] \| Other Current Liabilities [Member]
Derivative Liability, Current	1,400		1,400
Foreign Exchange Contract [Member] \| Other Noncurrent Liabilities [Member]
Derivative Liability, Noncurrent	$ 1,000		$ 1,000
Foreign Exchange Contract [Member] \| Casa Berardi [Member] \| Minimum [Member] \| United States of America, Dollars
Derivative, Forward Exchange Rate	1.2729		1.2729		1.2729	1.2729
Foreign Exchange Contract [Member] \| Casa Berardi [Member] \| Maximum [Member] \| United States of America, Dollars
Derivative, Forward Exchange Rate	1.3335		1.3335		1.3335	1.3335
Foreign Exchange Contract [Member] \| Casa Berardi [Member] \| Designated as Hedging Instrument [Member]
Derivative, Number of Instruments Held, Total	107		107		107	107
Derivative, Notional Amount	$ 198,000		$ 198,000		$ 256
Foreign Exchange Contract [Member] \| San Sebastian [Member] \| Minimum [Member] \| United States of America, Dollars
Derivative, Forward Exchange Rate	19.4		19.4		19.4	19.4
Foreign Exchange Contract [Member] \| San Sebastian [Member] \| Maximum [Member] \| United States of America, Dollars
Derivative, Forward Exchange Rate	20.855		20.855		20.855	20.855
Foreign Exchange Contract [Member] \| San Sebastian [Member] \| Designated as Hedging Instrument [Member]
Derivative, Number of Instruments Held, Total	33		33		33	33
Derivative, Notional Amount	$ 11,300		$ 11,300			$ 226.3
Commodity Contract [Member] \| Other Current Assets [Member]
Derivative Asset, Current	2,400		2,400
Commodity Contract [Member] \| Other Noncurrent Assets [Member]
Derivative Assets, Noncurrent, Total	12,300		12,300
Commodity Contract [Member] \| Other Current Liabilities [Member]
Derivative Liability, Current	1,200		1,200
Commodity Contract [Member] \| Other Noncurrent Liabilities [Member]
Derivative Liability, Noncurrent	$ 200		200
Unsettled Concentrate Sales Contracts [Member]
Derivative, Gain on Derivative			3,300
Forecasted Future Concentrate Contracts [Member]
Derivative, Gain on Derivative			$ 20,800