Note 8 - Derivative Instruments - Summary of Forward Sales Contracts (Details) oz in Thousands, lb in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2023 lb oz $ / $ $ / oz	Dec. 31, 2022 lb oz $ / oz $ / $
Silver 2023 Settlements For Provisional Sales Member
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Mass | oz	1,845	3,124
Underlying, Derivative Mass | $ / oz	24.35	21.55
Gold 2023 Settlements For Provisional Sales Member
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Mass | oz	7	8
Underlying, Derivative Mass | $ / oz	1,946	1,795
Zinc 2023 Settlements For Provisional Sales Member
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Mass | lb	1,709	18,629
Underlying, Derivative Mass | $ / $	1.31	1.38
Lead 2023 Settlements For Provisional Sales Member
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Mass | lb	8,433	11,960
Underlying, Derivative Mass | $ / $	1	0.98
Silver2023 Settlements For Forecasted Sales [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Mass | oz	1,845
Underlying, Derivative Mass | $ / oz	24.35
Gold2023 Settlements For Forecasted Sales [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Mass | oz	7
Underlying, Derivative Mass | $ / oz	1,946
Zinc 2023 Settlements for Forecasted Sales [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Mass | lb	441	37,533
Underlying, Derivative Mass | $ / $	1.51	1.34
Lead 2023 Settlements for Forecasted Sales [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Mass | lb	29,377	75,618
Underlying, Derivative Mass | $ / $	0.99	1
Lead 2024 Settlements for Forecasted Sales [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Mass | lb	75,178	45,856
Underlying, Derivative Mass | $ / $	0.98	0.99
Lead 2025 Settlements For Forecasted Sales [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Mass | lb	12,897
Underlying, Derivative Mass | $ / $	0.96