Note 6 - Business Segments and Sales of Products - Information About Reportable Segments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Net sales	$ 147,259	$ 134,279	$ 286,968	$ 276,823
Income (loss) from operations	3,756	3,975	15,705	19,846
Greens Creek [Member]
Net sales	74,605	71,339	140,455	130,189
Income (loss) from operations	25,516	15,418	48,668	29,532
Lucky Friday [Member]
Net sales	3,287	(187)	8,264	19,823
Income (loss) from operations	(5,261)	(8,212)	(9,407)	(4,332)
Casa Berardi [Member]
Net sales	56,103	43,822	111,651	85,534
Income (loss) from operations	1,014	(1,708)	4,264	(3,953)
San Sebastian [Member]
Net sales	13,264	19,305	26,598	41,277
Income (loss) from operations	(361)	11,892	4,656	25,346
Other Segments [Member]
Income (loss) from operations	$ (17,152)	$ (13,415)	$ (32,476)	$ (26,747)