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Note 11 - Derivative Instruments (Details Textual) $ in Thousands, MXN in Millions, CAD in Millions | 3 Months Ended | 9 Months Ended |
--- | --- | --- | ---
Sep. 30, 2017 USD ($) | Sep. 30, 2016 USD ($) | Sep. 30, 2017 USD ($) | Sep. 30, 2016 USD ($) | Sep. 30, 2017 CAD | Sep. 30, 2017 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 | $ 6,800 |  | $ 6,800 |  |  |
Gain (Loss) on Sale of Derivatives | (11,226) | $ 7 | (16,548) |  |  |
Gain (Loss) on Components Excluded from Assessment of Foreign Currency Cash Flow Hedge Effectiveness |  |  | 2 |  |  |
Derivative Liability, Fair Value, Amount Not Offset Against Collateral | 14,400 |  | 14,400 |  |  |
Derivative, Fair Value, Obligations Under the Agreements | 14,400 |  | 14,400 |  |  |
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 | 2,900 |  | 2,900 |  |  |
Foreign Exchange Contract [Member] | Other Current Assets [Member] |  |  |  |  |  |
Derivative Asset, Current | 2,800 |  | 2,800 |  |  |
Foreign Exchange Contract [Member] | Other Noncurrent Liabilities [Member] |  |  |  |  |  |
Derivative Asset, Noncurrent | $ 3,700 |  | $ 3,700 |  |  |
Foreign Exchange Contract [Member] | Casa Berardi [Member] | Minimum [Member] | United States of America, Dollars |  |  |  |  |  |
Derivative, Forward Exchange Rate | 1.2787 |  | 1.2787 |  | 1.2787 | 1.2787
Foreign Exchange Contract [Member] | Casa Berardi [Member] | Maximum [Member] | United States of America, Dollars |  |  |  |  |  |
Derivative, Forward Exchange Rate | 1.338 |  | 1.338 |  | 1.338 | 1.338
Foreign Exchange Contract [Member] | San Sebastian [Member] | Minimum [Member] | United States of America, Dollars |  |  |  |  |  |
Derivative, Forward Exchange Rate | 19.591 |  | 19.591 |  | 19.591 | 19.591
Foreign Exchange Contract [Member] | San Sebastian [Member] | Maximum [Member] | United States of America, Dollars |  |  |  |  |  |
Derivative, Forward Exchange Rate | 21 |  | 21 |  | 21 | 21
Foreign Exchange Contract [Member] | Designated as Hedging Instrument [Member] | Casa Berardi [Member] |  |  |  |  |  |
Derivative, Number of Instruments Held | 94 |  | 94 |  | 94 | 94
Derivative, Notional Amount | $ 154,000 |  | $ 154,000 |  | CAD 200.1 |
Foreign Exchange Contract [Member] | Designated as Hedging Instrument [Member] | San Sebastian [Member] |  |  |  |  |  |
Derivative, Number of Instruments Held | 6 |  | 6 |  | 6 | 6
Derivative, Notional Amount | $ 2,200 |  | $ 2,200 |  |  | MXN 43.3
Commodity Contract [Member] | Other Current Assets [Member] |  |  |  |  |  |
Derivative Asset, Current | 400 |  | 400 |  |  |
Derivative Asset, Fair Value, Gross Liability | 100 |  | 100 |  |  |
Commodity Contract [Member] | Other Noncurrent Liabilities [Member] |  |  |  |  |  |
Derivative Liability, Noncurrent | 4,000 |  | 4,000 |  |  |
Commodity Contract [Member] | Other Current Liabilities [Member] |  |  |  |  |  |
Derivative Liability, Current | 7,900 |  | 7,900 |  |  |
Derivative Liability, Fair Value, Gross Asset | $ 200 |  | 200 |  |  |
Unsettled Concentrate Sales Contracts [Member] |  |  |  |  |  |
Derivative, Loss on Derivative |  |  | 3,900 |  |  |
Forecasted Future Concentrate Contracts [Member] |  |  |  |  |  |
Derivative, Loss on Derivative |  |  | $ 16,500 |  |  |

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- Definition Aggregate notional amount specified by the derivative(s). Expressed as an absolute value. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 12 -Section 13 -Sentence Column B + Details
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- Definition 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. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 10A -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=84228862&loc=SL7669646-108580 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=84228862&loc=d3e637-108580 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 14A -URI http://asc.fasb.org/extlink&oid=84228862&loc=SL7669686-108580 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 14 -URI http://asc.fasb.org/extlink&oid=84228862&loc=d3e681-108580 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 30 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=35736893&loc=d3e80784-113994 + Details
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