Note 11 - Business Segments, Sales of Products and Significant Customers (Details Textual) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) oz T	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Number of Reportable Segments	5
Derivative, Loss on Derivative	$ 1,300		$ 6,000
Derivative, Gain on Derivative		$ 8,100
Accounts Receivable, after Allowance for Credit Loss, Current, Total	11,952	4,184
Accounts Receivable, Allowance for Credit Loss, Ending Balance	0	0
Employee Labor Strike Related Costs	12,051	20,693	21,301
Lucky Friday [Member] | Suspension Costs [Member]
Employee Labor Strike Related Costs	7,800	14,600	17,100
Lucky Friday [Member] | Non-cash Depreciation Expense [Member]
Employee Labor Strike Related Costs	$ 4,300	$ 5,000	$ 4,200
Silver Contracts [Member]
Metals Contained in Concentrates | oz	2,500,000
Gold [Member]
Metals Contained in Concentrates | oz	10,020
Zinc [Member]
Metals Contained in Concentrates | T	11,627
Lead [Member]
Metals Contained in Concentrates | T	4,939