Note 11 - Business Segments, Sales of Products and Significant Customers - Information About Reportable Segments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Net sales	$ 673,266	$ 567,137	$ 577,775
Income (loss) from operations	(57,109)	(39,126)	60,106
Capital additions (including non-cash additions)	123,729	146,451	105,752
Depreciation, depletion and amortization	199,518	134,044	120,599
Other significant non-cash items	5,875	(9,542)	57,463
Identifiable assets	2,637,308	2,703,944	2,345,158
Greens Creek [Member]
Net sales	299,722	265,650	278,297
Income (loss) from operations	84,868	70,293	70,132
Capital additions (including non-cash additions)	35,829	43,631	35,255
Depreciation, depletion and amortization	47,587	46,511	56,328
Other significant non-cash items	2,868	3,325	2,685
Identifiable assets	639,047	637,386	671,960
Lucky Friday [Member]
Net sales	16,621	9,750	21,555
Income (loss) from operations	(12,520)	(20,199)	(16,037)
Capital additions (including non-cash additions)	7,861	14,236	6,268
Depreciation, depletion and amortization	1,175	1,012	2,447
Other significant non-cash items	996	618	2,011
Identifiable assets	440,615	437,499	432,400
Casa Berardi [Member]
Net sales	192,944	210,339	192,165
Income (loss) from operations	(33,499)	881	(534)
Capital additions (including non-cash additions)	33,906	39,816	51,327
Depreciation, depletion and amortization	73,960	71,302	59,131
Other significant non-cash items	5,203	696	33
Identifiable assets	703,511	754,248	784,706
San Sebastian [Member]
Net sales	56,210	50,224	85,758
Income (loss) from operations	569	(14)	53,591
Capital additions (including non-cash additions)	3,906	8,492	9,994
Depreciation, depletion and amortization	9,772	4,602	2,693
Other significant non-cash items	492	419	468
Identifiable assets	48,294	44,152	62,198
Nevada Operations [Member]
Net sales	107,769	31,174	0
Income (loss) from operations	(49,224)	(26,715)	0
Capital additions (including non-cash additions)	42,154	35,721	0
Depreciation, depletion and amortization	67,024	10,617	0
Other significant non-cash items	2,911	8,758	0
Identifiable assets	528,466	581,194	0
Other Segments [Member]
Income (loss) from operations	(47,303)	(63,372)	(47,046)
Capital additions (including non-cash additions)	73	4,555	2,908
Other significant non-cash items	(6,595)	(23,358)	52,266
Identifiable assets	$ 277,375	$ 249,465	$ 393,894