Note 4- Business Segments, Sales of Products and Significant Customers - Sales from Continuing Operations to Significant Metals Customers As a Percentage of Total Sales (Details) - Customer Concentration Risk [Member] - Revenue from Contract with Customer Benchmark [Member]	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
CIBC [Member]
Significant metal customers	37.20%	32.70%	23.10%
Teck Metals Ltd [Member]
Significant metal customers	21.50%	16.10%	8.20%
Ocean Partners [Member]
Significant metal customers	6.20%	13.90%	5.70%
Korea Zinc [Member]
Significant metal customers	21.60%	13.30%	17.40%
Scotia [Member]
Significant metal customers	0.00%	2.90%	24.00%