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Note 5 - Environmental and Reclamation Activities (Tables) | 12 Months Ended
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Dec. 31, 2018
Notes Tables |
Schedule of Accrued Liabilities [Table Text Block] |
|  | 2018 |  |  | 2017 |
Operating properties: |  |  |  |  |  |  |  |
Greens Creek |  | $ | 41,839 |  |  | $ | 41,677 |
Lucky Friday |  |  | 10,698 |  |  |  | 9,911 |
Casa Berardi |  |  | 5,843 |  |  |  | 6,729 |
San Sebastian |  |  | 7,765 |  |  |  | 5,067 |
Nevada Operations |  |  | 23,272 |  |  |  | — |
Non-operating properties: |  |  |  |  |  |  |  |
Troy mine |  |  | 8,971 |  |  |  | 12,724 |
Johnny M |  |  | 5,813 |  |  |  | 5,813 |
Republic |  |  | 1,500 |  |  |  | 1,500 |
All other sites |  |  | 2,688 |  |  |  | 2,624 |
Total |  |  | 108,389 |  |  |  | 86,045 |
Reclamation and closure costs, current |  |  | (3,410 | ) |  |  | (6,679 | )
Reclamation and closure costs, long-term |  | $ | 104,979 |  |  | $ | 79,366 |
Accrued Reclamation and Closure Cost Liability Activity [Table Text Block] |
Balance at January 1, 2016 |  | $ | 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 |
Accruals for estimated costs |  |  | 250 |
Accretion expense |  |  | 5,309 |
Revision of estimated cash flows due to changes in reclamation plans |  |  | 1,280 |
Liability addition due to acquisition of the Nevada Operations unit |  |  | 19,571 |
Payment of reclamation obligations |  |  | (4,066 | )
Balance at December 31, 2018 |  | $ | 108,389 |
Schedule of Change in Asset Retirement Obligation [Table Text Block] |
|  | 2018 |  |  | 2017 |
Balance January 1 |  | $ | 63,384 |  |  | $ | 59,275 |
Changes in obligations due to changes in reclamation plans |  |  | 1,280 |  |  |  | (578 | )
Addition due to acquisition of the Nevada Operations unit |  |  | 19,571 |  |  |  | — |
Accretion expense |  |  | 5,295 |  |  |  | 4,870 |
Payment of reclamation obligations |  |  | (113 | ) |  |  | (183 | )
Balance at December 31 |  | $ | 89,417 |  |  | $ | 63,384 |

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