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Note 4 - Environmental and Reclamation Activities (Tables) | 12 Months Ended
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Dec. 31, 2017
Notes Tables |
Schedule of Accrued Liabilities [Table Text Block] |
|  | 2017 |  |  | 2016 |
Operating properties: |  |  |  |  |  |  |  |
Greens Creek |  | $ | 41,677 |  |  | $ | 39,014 |
Lucky Friday |  |  | 9,911 |  |  |  | 9,194 |
Casa Berardi |  |  | 6,729 |  |  |  | 5,475 |
San Sebastian |  |  | 5,067 |  |  |  | 5,592 |
Non-operating properties: |  |  |  |  |  |  |  |
Troy mine |  |  | 12,724 |  |  |  | 16,167 |
Johnny M |  |  | 5,813 |  |  |  | 5,830 |
Republic |  |  | 1,500 |  |  |  | 1,500 |
All other sites |  |  | 2,624 |  |  |  | 2,808 |
Total |  |  | 86,045 |  |  |  | 85,580 |
Reclamation and closure costs, current |  |  | (6,679 | ) |  |  | (5,653 | )
Reclamation and closure costs, long-term |  | $ | 79,366 |  |  | $ | 79,927 |
Accrued Reclamation and Closure Cost Liability Activity [Table Text Block] |
Balance at January 1, 2015 |  | $ | 57,250 |
Accruals for estimated costs |  |  | 15,114 |
Accretion expense |  |  | 1,904 |
Revision of estimated cash flows due to changes in reclamation plans |  |  | 4,112 |
Addition due to development and production at our San Sebastian unit |  |  | 1,189 |
Liability addition due to acquisition of Revett |  |  | 17,513 |
Payment of reclamation obligations |  |  | (1,544 | )
Balance at December 31, 2015 |  |  | 95,538 |
Accruals for estimated costs |  |  | 705 |
Accretion expense |  |  | 3,158 |
Revision of estimated cash flows due to changes in reclamation plans |  |  | 2,759 |
Liability addition due to acquisition of Mines Management |  |  | 1,124 |
Payment of reclamation obligations |  |  | (17,704 | )
Balance at December 31, 2016 |  |  | 85,580 |
Accruals for estimated costs |  |  | 16 |
Accretion expense |  |  | 4,870 |
Revision of estimated cash flows due to changes in reclamation plans |  |  | (578 | )
Payment of reclamation obligations |  |  | (3,843 | )
Balance at December 31, 2017 |  | $ | 86,045 |
Schedule of Change in Asset Retirement Obligation [Table Text Block] |
|  | 2017 |  |  | 2016 |
Balance January 1 |  | $ | 59,275 |  |  | $ | 53,433 |
Changes in obligations due to changes in reclamation plans |  |  | (578 | ) |  |  | 2,760 |
Accretion expense |  |  | 4,870 |  |  |  | 3,158 |
Payment of reclamation obligations |  |  | (183 | ) |  |  | (76 | )
Balance at December 31 |  | $ | 63,384 |  |  | $ | 59,275 |

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