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Note 4 - Business Segments, Sales of Products and Significant Customers - Percentage of Sales by Segments (Details) - Revenue Benchmark [Member] - Customer Concentration Risk [Member]
12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Dec. 31, 2019
Percentage of sales 100.00% 100.00% 100.00%
Greens Creek [Member]      
Percentage of sales 47.60% 47.40% 44.50%
Lucky Friday [Member]      
Percentage of sales 16.30% 9.10% 2.50%
Casa Berardi [Member]      
Percentage of sales 30.40% 30.20% 28.70%
Nevada Operations [Member]      
Percentage of sales 5.70% 8.50% 16.00%
Other Segments [Member]      
Percentage of sales 0.00% 4.80% 8.30%