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Note 6 - Business Segments and Sales of Products (Details Textual) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018 USD ($) oz T	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($) oz T	Jun. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)
Number of Reportable Segments			4
Derivative, Gain on Derivative	$ 2,700	$ 800	$ 3,300
Derivative, Loss on Derivative				$ 3,200
Accounts Receivable, Net, Current, Total	9,717		9,717		$ 14,805
Allowance for Doubtful Accounts Receivable, Ending Balance	0		0		$ 0
Employee Labor Strike Related Costs	6,801	$ 8,024	11,818	9,605
Lucky Friday [Member]
Long-Lived Assets	$ 428,100		$ 428,100
Estimated Mine Life			22 years
Lucky Friday [Member] \| Suspension Costs [Member]
Employee Labor Strike Related Costs			$ 9,400	7,600
Lucky Friday [Member] \| Non-cash Depreciation Expense [Member]
Employee Labor Strike Related Costs			$ 2,400	$ 2,000
Silver [Member]
Metals Contained in Concentrates \| oz	1,200,000		1,200,000
Gold [Member]
Metals Contained in Concentrates \| oz	5,842		5,842
Zinc [Member]
Metals Contained in Concentrates \| T	11,696		11,696
Lead [Member]
Metals Contained in Concentrates \| T	2,792		2,792