Note 6 - Business Segments and Sales of Products - Percentage of Sales by Segments (Details) - Revenue Benchmark [Member]	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Percentage of sales	100.00%	100.00%	100.00%	100.00%
Greens Creek [Member]
Percentage of sales	47.00%	37.00%	46.00%	44.00%
Lucky Friday [Member]
Percentage of sales	10.00%	2.00%	7.00%	2.00%
Casa Berardi [Member]
Percentage of sales	27.00%	33.00%	30.00%	31.00%
San Sebastian [Member]
Percentage of sales	5.00%	10.00%	5.00%	9.00%
Nevada Operations [Member]
Percentage of sales	11.00%	18.00%	12.00%	14.00%