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Note 5 - Environmental and Reclamation Activities (Details Textual)
$ in Thousands
12 Months Ended
Dec. 31, 2021
USD ($)
Dec. 31, 2020
USD ($)
Dec. 31, 2019
USD ($)
Dec. 31, 2018
USD ($)
Accrual for Environmental Loss Contingencies, Ending Balance $ 113,231 $ 116,048 $ 108,374 $ 108,389
Greens Creek [Member]        
Asset Retirement Obligation, Liabilities Incurred 8,600      
Casa Berardi [Member]        
Asset Retirement Obligation, Liabilities Incurred 100      
Lucky Friday [Member]        
Asset Retirement Obligation, Liabilities Incurred 300      
Nevada Operations [Member]        
Asset Retirement Obligation, Liabilities Incurred 300      
Asset Retirement Obligation, Revision of Estimate Before Discounting $ 35,200 $ 34,200    
Minimum [Member]        
Inflation Rate, Asset Retirement Obligation 2.00%      
Minimum [Member] | Reclamation and Abandonment Costs [Member] | Measurement Input, Risk Free Interest Rate [Member]        
Derivative Liability, Measurement Input 0.0575      
Minimum [Member] | Asset Retirement Obligation [Member] | Measurement Input, Risk Free Interest Rate [Member]        
Derivative Liability, Measurement Input 0.0275      
Maximum [Member]        
Inflation Rate, Asset Retirement Obligation 4.00%      
Maximum [Member] | Reclamation and Abandonment Costs [Member] | Measurement Input, Risk Free Interest Rate [Member]        
Derivative Liability, Measurement Input 0.145      
Maximum [Member] | Asset Retirement Obligation [Member] | Measurement Input, Risk Free Interest Rate [Member]        
Derivative Liability, Measurement Input 0.075