Note 10 - Commitments, Contingencies and Obligations (Details Textual) - USD ($) $ in Thousands		1 Months Ended			3 Months Ended		9 Months Ended
	Jul. 12, 2022	Jul. 31, 2018	Aug. 31, 2012	Jun. 30, 2011	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Loss Contingencies [Line Items]
Environmental remediation expense					$ 2,256	$ 1,781	$ 6,411	$ 4,154
Finance lease, liability, to be paid					32,161		32,161
Lessee, operating lease, liability, to be paid					12,439		12,439
Lease Commitments [Member]
Loss Contingencies [Line Items]
Lessee, operating lease, liability, to be paid					12,400		12,400
Performance Obligation Commitments [Member]
Loss Contingencies [Line Items]
Surety Bonds					193,400		193,400
Letters of credit outstanding, amount					6,700		6,700
Greens Creek [Member]
Loss Contingencies [Line Items]
Contractual obligation					32,200		32,200
Greens Creek [Member] | Purchase Orders and Commitment [Member]
Loss Contingencies [Line Items]
Contractual obligation					15,000		15,000
Lucky Friday [Member]
Loss Contingencies [Line Items]
EPA maximum for statutory penalties, per day/violation	$ 59,973
EPA maximum for administrative penalties, per day/violation	23,989
EPA maximum for administrative penalties	$ 299,989
Lucky Friday [Member] | Purchase Orders and Commitment [Member]
Loss Contingencies [Line Items]
Contractual obligation					9,700		9,700
Casa Berardi [Member] | Purchase Orders and Commitment [Member]
Loss Contingencies [Line Items]
Contractual obligation					3,500		3,500
Nevada Operations [Member] | Purchase Orders and Commitment [Member]
Loss Contingencies [Line Items]
Contractual obligation					1,800		1,800
Keno Hill [Member] | Purchase Orders and Commitment [Member]
Loss Contingencies [Line Items]
Contractual obligation					$ 10,300		10,300
Johnny M Mine Area near San Mateo, New Mexico [Member]
Loss Contingencies [Line Items]
Payment of response costs			$ 1,100
Estimated response costs		$ 9,600
Environmental remediation expense			10,100
Johnny M Mine Area near San Mateo, New Mexico [Member] | Environmental Remediation Past Response Costs [Member]
Loss Contingencies [Line Items]
Accrual for environmental loss contingencies, period increase (decrease)			$ 10,100				$ 10,100
Carpenter Snow Creek Superfund Site, Cascade County, Montana [Member]
Loss Contingencies [Line Items]
Estimated response costs				$ 4,500
Estimated future response cost				$ 100,000