Note 12 - Business Segments, Sales of Products and Significant Customers - Information About Reportable Segments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Net sales	$ 691,873	$ 673,266	$ 567,137
Income (loss) from operations	51,581	(57,109)	(39,126)
Capital additions (including non-cash additions)	102,519	123,729	146,451
Depreciation, depletion and amortization	157,130	199,518	134,044
Other significant non-cash items	11,164	5,875	(9,542)
Identifiable assets	2,667,724	2,637,308	2,703,944
Greens Creek [Member]
Net sales	327,820	299,722	265,650
Income (loss) from operations	108,230	84,868	70,293
Capital additions (including non-cash additions)	23,665	35,829	43,631
Depreciation, depletion and amortization	49,692	47,587	46,511
Other significant non-cash items	3,103	2,868	3,325
Identifiable assets	610,360	639,047	637,386
Lucky Friday [Member]
Net sales	63,025	16,621	9,750
Income (loss) from operations	(1,711)	(12,520)	(20,199)
Capital additions (including non-cash additions)	27,284	7,861	14,236
Depreciation, depletion and amortization	11,473	1,175	1,012
Other significant non-cash items	881	996	618
Identifiable assets	520,463	440,615	437,499
Casa Berardi [Member]
Net sales	209,224	192,944	210,339
Income (loss) from operations	1,359	(33,499)	881
Capital additions (including non-cash additions)	47,576	33,906	39,816
Depreciation, depletion and amortization	69,572	73,960	71,302
Other significant non-cash items	(1,741)	5,203	696
Identifiable assets	694,522	703,511	754,248
San Sebastian [Member]
Net sales	32,906	56,210	50,224
Income (loss) from operations	2,793	569	(14)
Capital additions (including non-cash additions)		3,906	8,492
San Sebastian	(47)
Depreciation, depletion and amortization	3,548	9,772	4,602
Other significant non-cash items	456	492	419
Identifiable assets	42,617	48,294	44,152
Nevada Operations [Member]
Net sales	58,898	107,769	31,174
Income (loss) from operations	(6,674)	(49,224)	(26,715)
Capital additions (including non-cash additions)	4,003	42,154	35,721
Depreciation, depletion and amortization	22,845	67,024	10,617
Other significant non-cash items	2,039	2,911	8,758
Identifiable assets	513,309	528,466	581,194
Other Segments [Member]
Income (loss) from operations	(52,416)	(47,303)	(63,372)
Capital additions (including non-cash additions)	38	73	4,555
Other significant non-cash items	6,426	(6,595)	(23,358)
Identifiable assets	$ 286,453	$ 277,375	$ 249,465