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Note 4 - Environmental and Reclamation Activities (Details Textual) - USD ($) $ in Thousands |  | 1 Months Ended | 3 Months Ended | 12 Months Ended |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Nov. 07, 2016 | Aug. 31, 2016 | Oct. 31, 2013 | Oct. 31, 2012 | Oct. 31, 2011 | Dec. 31, 2016 | Sep. 30, 2016 | Jun. 30, 2015 | Dec. 31, 2016 | Dec. 31, 2015 | Jun. 15, 2015 | Dec. 31, 2014 | Aug. 31, 2014 | Jul. 30, 2014 | Dec. 31, 2013
Other Accrued Liabilities |  |  |  |  | $ 264,400 |  |  |  |  |  |  |  |  |  |
Payments for Legal Settlements |  |  | $ 15,000 | $ 25,000 | $ 168,000 |  |  |  |  |  |  |  |  |  |
Payment of Proceeds from Warrants Exercised |  |  |  |  |  |  |  |  |  |  |  |  | $ 41,300 | $ 14,100 |
Accrued Reclamation and Closure Costs Total |  |  |  |  |  | $ 85,580 |  |  | $ 85,580 | $ 95,538 |  | $ 57,250 |  |  | $ 105,191
Asset Retirement Obligation, Revision of Estimate |  |  |  |  |  |  |  |  | 2,760 | 4,112 |  |  |  |  |
Asset Retirement Obligation, Liabilities Incurred |  |  |  |  |  |  |  |  |  | $ 1,189 |  |  |  |  |
Minimum [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Risk Free Interest Rate |  |  |  |  |  | 6.00% |  |  | 6.00% |  |  |  |  |  |
Inflation Rate, Asset Retirement Obligation |  |  |  |  |  |  |  |  | 2.00% |  |  |  |  |  |
Maximum [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Risk Free Interest Rate |  |  |  |  |  | 14.50% |  |  | 14.50% |  |  |  |  |  |
Inflation Rate, Asset Retirement Obligation |  |  |  |  |  |  |  |  | 3.25% |  |  |  |  |  |
Nelson Tunnel/Commodore Site [Member] | United States and Colorado [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Loss Contingency Accrual, Payments |  | $ 6,000 |  |  |  |  |  |  |  |  |  |  |  |  |
Gilt Edge Mine Superfund Site [Member] | United States and South Dakota [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Loss Contingency Accrual, Payments | $ 3,900 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Gilt Edge Mine Superfund Site [Member] | United States, South Dakota, Insurers and Another Potentially Responsible Party [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Loss Contingency Accrual, Payments | $ 6,400 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Gilt Edge Site and Nelson Tunnel/Commodore Site [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liability for Remediation |  |  |  |  |  |  |  | $ 9,900 |  |  |  |  |  |  |
Lucky Friday [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Risk Free Interest Rate |  |  |  |  |  | 6.50% |  |  | 6.50% |  |  |  |  |  |
Asset Retirement Obligation, Revision of Estimate Before Discounting |  |  |  |  |  |  | $ 22,600 |  |  |  |  |  |  |  |
Asset Retirement Obligation, Revision of Estimate |  |  |  |  |  |  | 3,300 |  |  |  |  |  |  |  |
San Sebastian [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Asset Retirement Obligation, Revision of Estimate Before Discounting |  |  |  |  |  |  | 4,300 |  |  |  |  |  |  |  |
Asset Retirement Obligation, Liabilities Incurred |  |  |  |  |  |  | 4,500 |  |  |  |  |  |  |  |
Greens Creek [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Asset Retirement Obligation, Revision of Estimate Before Discounting |  |  |  |  |  | $ 3,700 |  |  |  |  |  |  |  |  |
Asset Retirement Obligation, Revision of Estimate |  |  |  |  |  | $ (5,000) |  |  |  |  |  |  |  |  |
Revett Mining Company, Inc. [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Ownership Percentage |  |  |  |  |  |  |  |  |  |  | 100.00% |  |  |  |
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Reclamation Liability |  |  |  |  |  |  |  | 17,500 |  |  | $ 17,513 |  |  |  |
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Reclamation Insurance Asset |  |  |  |  |  |  |  | $ 16,800 |  |  | $ 16,800 |  |  |  |
Proceeds from Insurance Settlement, Investing Activities |  |  |  |  |  |  | $ 16,000 |  |  |  |  |  |  |  |
Revett Mining Company, Inc. [Member] | Mining Properties and Mineral Rights [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Ownership Percentage |  |  |  |  |  |  |  | 100.00% |  |  |  |  |  |  |

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