Note 12 - Business Segments, Sales of Products and Significant Customers - Percentage of Sales by Segments (Details) - Sales Revenue, Net [Member]	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Percentage of sales	100.00%	100.00%	100.00%
Greens Creek [Member]
Percentage of sales	46.70%	48.10%	40.30%
Lucky Friday [Member]
Percentage of sales	1.80%	3.80%	14.70%
Casa Berardi [Member]
Percentage of sales	37.10%	33.30%	27.40%
San Sebastian [Member]
Percentage of sales	8.90%	14.80%	17.60%
Nevada Operations [Member]
Percentage of sales	5.50%

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
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-URI http://asc.fasb.org/extlink&oid=109250915&loc=d3e13531-108611

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
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-URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6404-108592

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