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Note 5 - Environmental and Reclamation Activities (Tables) | 12 Months Ended
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Dec. 31, 2020
Notes Tables |
Schedule of Accrued Liabilities [Table Text Block] |
|  | 2020 |  |  | 2019 |
Operating properties: |  |  |  |  |  |  |  |
Greens Creek |  | $ | 42,716 |  |  | $ | 44,695 |
Lucky Friday |  |  | 12,818 |  |  |  | 10,473 |
Casa Berardi |  |  | 11,730 |  |  |  | 4,510 |
San Sebastian |  |  | 6,882 |  |  |  | 7,399 |
Nevada Operations |  |  | 26,062 |  |  |  | 24,754 |
Non-operating properties: |  |  |  |  |  |  |  |
Troy mine |  |  | 5,340 |  |  |  | 6,069 |
Johnny M |  |  | 6,065 |  |  |  | 6,065 |
Republic |  |  | 1,500 |  |  |  | 1,500 |
All other sites |  |  | 2,935 |  |  |  | 2,909 |
Total |  |  | 116,048 |  |  |  | 108,374 |
Reclamation and closure costs, current |  |  | (5,582 | ) |  |  | (4,581 | )
Reclamation and closure costs, long-term |  | $ | 110,466 |  |  | $ | 103,793 |
Accrued Reclamation and Closure Cost Liability Activity [Table Text Block] |
Balance at January 1, 2018 |  | $ | 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 |
Accruals for estimated costs |  |  | 472 |
Accretion expense |  |  | 7,122 |
Revision of estimated cash flows due to changes in reclamation plans |  |  | (4,522 | )
Payment of reclamation obligations |  |  | (3,087 | )
Balance at December 31, 2019 |  |  | 108,374 |
Accretion expense |  |  | 5,912 |
Revision of estimated cash flows due to changes in reclamation plans |  |  | 2,543 |
Payment of reclamation obligations |  |  | (781 | )
Balance at December 31, 2020 |  | $ | 116,048 |
Schedule of Change in Asset Retirement Obligation [Table Text Block] |
|  | 2020 |  |  | 2019 |
Balance January 1 |  | $ | 91,831 |  |  | $ | 89,417 |
Changes in obligations due to changes in reclamation plans |  |  | 2,543 |  |  |  | (4,522 | )
Accretion expense |  |  | 5,912 |  |  |  | 7,122 |
Payment of reclamation obligations |  |  | (78 | ) |  |  | (186 | )
Balance at December 31 |  | $ | 100,208 |  |  | $ | 91,831 |

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