Note 6 - Business Segments and Sales of Products - Information About Reportable Segments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Mar. 31, 2020	Dec. 31, 2019
Net sales	$ 199,703	$ 161,532	$ 502,983	$ 448,321
Income (loss) from operations	31,329	(5,113)	26,243	(64,714)
Greens Creek	2,615,150		2,615,150		$ 2,615,150	$ 2,637,308
Greens Creek [Member]
Net sales	93,494	59,015	232,218	194,542
Income (loss) from operations	41,527	17,556	72,394	52,130
Greens Creek					612,963	639,047
Lucky Friday [Member]
Net sales	20,812	4,017	35,097	11,150
Income (loss) from operations	957	(3,727)	(12,381)	(8,779)
Greens Creek					508,053	440,615
Casa Berardi [Member]
Net sales	53,554	53,453	149,731	139,015
Income (loss) from operations	(828)	(380)	(1,504)	(26,262)
Greens Creek					695,629	703,511
San Sebastian [Member]
Net sales	9,138	15,435	23,998	39,028
Income (loss) from operations	1,946	1,077	1,766	(2,358)
Greens Creek					35,973	48,294
Nevada Operations [Member]
Net sales	22,705	29,612	61,939	64,586
Income (loss) from operations	5,489	(8,346)	6,112	(43,812)
Greens Creek					520,871	528,466
Other Segments [Member]
Income (loss) from operations	$ (17,762)	$ (11,293)	$ (40,144)	$ (35,633)
Greens Creek					$ 241,661	$ 277,375