Note 6 - Business Segments and Sales of Products - Percentage of Sales by Segments (Details) - Revenue Benchmark [Member]	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Percentage of sales	100.00%	100.00%	100.00%	100.00%
Greens Creek [Member]
Percentage of sales	51.00%	41.00%	45.00%	48.00%
Lucky Friday [Member]
Percentage of sales	7.00%	4.00%	5.00%	2.00%
Casa Berardi [Member]
Percentage of sales	30.00%	34.00%	32.00%	30.00%
San Sebastian [Member]
Percentage of sales	3.00%	8.00%	5.00%	8.00%
Nevada Operations [Member]
Percentage of sales	9.00%	13.00%	13.00%	12.00%