Note 5 - Environmental and Reclamation Activities - Liabilities Accrued for Reclamation and Closure Costs (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reclamation and closure costs	$ 113,231	$ 116,048	$ 108,374	$ 108,389
Reclamation and closure costs, current	(9,259)	(5,582)
Reclamation and closure costs, long-term	103,972	110,466
Operating Properties [Member] | Greens Creek [Member]
Reclamation and closure costs	37,474	42,716
Operating Properties [Member] | Lucky Friday [Member]
Reclamation and closure costs	13,543	12,818
Operating Properties [Member] | Casa Berardi [Member]
Reclamation and closure costs	12,497	11,730
Operating Properties [Member] | Nevada Operations [Member]
Reclamation and closure costs	27,068	26,062
Operating Properties [Member] | San Sebastian [Member]
Reclamation and closure costs	4,451	6,882
Non-Operating Properties [Member] | Troy Mine [Member]
Reclamation and closure costs	4,813	5,340
Non-Operating Properties [Member] | Johnny M Mine Area near San Mateo, New Mexico [Member]
Reclamation and closure costs	8,947	6,065
Non-Operating Properties [Member] | Republic [Member]
Reclamation and closure costs	1,500	1,500
Non-Operating Properties [Member] | All Other Sites [Member]
Reclamation and closure costs	$ 2,938	$ 2,935