Note 3 - Business Segments and Sales of Products - Information About Reportable Segments (Details) - USD ($) $ in Thousands	3 Months Ended						6 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Jun. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Net sales	$ 193,560			$ 199,703					$ 622,395	$ 502,983
Income (loss) from operations	(8,572)	$ 29,133	$ 41,038	36,515	$ 13,905	$ (13,046)	$ 70,171	$ 1,536	61,599	38,051	$ 66,978	$ (46,678)	$ (35,058)
Total assets	2,674,417								2,674,417		2,700,210	$ 2,660,774
Greens Creek [Member]
Net sales	84,806			93,494					296,978	232,218
Income (loss) from operations	26,572			44,477					127,605	76,762
Total assets	607,207								607,207		610,360
Lucky Friday [Member]
Net sales	29,783			20,812					98,550	35,097
Income (loss) from operations	6,187			950					24,247	(12,388)
Total assets	512,742								512,742		520,463
Casa Berardi [Member]
Net sales	56,065			53,554					185,098	149,731
Income (loss) from operations	(6,233)			1,419					4,944	5,330
Total assets	705,328								705,328		727,008
San Sebastian [Member]
Net sales	0			9,138					176	23,998
Income (loss) from operations	(1,727)			1,946					(4,951)	1,766
Total assets	38,186								38,186		42,617
Nevada Operations [Member]
Net sales	22,906			22,705					41,593	61,939
Income (loss) from operations	(12,077)			5,486					(35,558)	6,830
Total assets	477,621								477,621		513,309
Other Segments [Member]
Income (loss) from operations	(21,294)			$ (17,763)					(54,688)	$ (40,249)
Total assets	$ 333,333								$ 333,333		$ 286,453