Note 6 - Business Segments and Sales of Products - Information About Reportable Segments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Net sales	$ 166,355	$ 134,172	$ 303,280	$ 286,789
Income (loss) from operations	9,874	(43,477)	(5,086)	(59,601)
Greens Creek	2,603,408		2,603,408		$ 2,637,308
Greens Creek [Member]
Net sales	84,890	55,398	138,724	135,527
Income (loss) from operations	26,751	9,141	30,867	34,574
Greens Creek	618,726		618,726		639,047
Lucky Friday [Member]
Net sales	11,455	4,951	14,285	7,133
Income (loss) from operations	(5,218)	(2,271)	(13,338)	(5,052)
Greens Creek	501,690		501,690		440,615
Casa Berardi [Member]
Net sales	50,005	45,500	96,177	85,562
Income (loss) from operations	3,204	(15,363)	(676)	(25,882)
Greens Creek	693,259		693,259		703,511
San Sebastian [Member]
Net sales	4,934	10,993	14,860	23,593
Income (loss) from operations	(859)	(1,923)	(180)	(3,435)
Greens Creek	32,915		32,915		48,294
Nevada Operations [Member]
Net sales	15,071	17,330	39,234	34,974
Income (loss) from operations	(2,266)	(21,475)	623	(35,466)
Greens Creek	522,822		522,822		528,466
Other Segments [Member]
Income (loss) from operations	(11,738)	$ (11,586)	(22,382)	$ (24,340)
Greens Creek	$ 233,996		$ 233,996		$ 277,375