Note 2 - Business Segments and Sales of Products - Sales of Products (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Net sales	$ 146,339	$ 193,560	$ 524,080	$ 622,395
Net sales	146,274	193,560	524,015	622,395
Less: Smelter and refining charges	(13,023)	(11,669)	(38,543)	(38,189)
Silver Contracts [Member]
Net sales	45,924	61,890	182,306	232,414
Gold [Member]
Net sales	69,289	94,984	228,475	282,471
Lead [Member]
Net sales	16,033	18,082	56,912	56,198
Zinc [Member]
Net sales	$ 28,051	$ 30,273	$ 94,865	$ 89,501