Note 11 - Commitments, Contingencies and Obligations (Details Textual) - USD ($) $ in Thousands	1 Months Ended		3 Months Ended		9 Months Ended
	Jul. 31, 2018	Jun. 30, 2011	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Loss Contingencies [Line Items]
Environmental remediation expense			$ 1,268	$ 1,542	$ 2,902	$ 3,681
Lessee, operating lease, liability, to be paid			11,936		11,936
Lease Commitments [Member]
Loss Contingencies [Line Items]
Lessee, operating lease, liability, to be paid			11,900		11,900
Performance Obligation Commitments [Member]
Loss Contingencies [Line Items]
Surety bonds			218,800		218,800
Letters of credit outstanding, amount			6,700		6,700
Greens Creek [Member]
Loss Contingencies [Line Items]
Contractual obligation			17,200		17,200
Greens Creek [Member] | Purchase Orders and Commitment [Member]
Loss Contingencies [Line Items]
Contractual obligation			10,700		10,700
Lucky Friday [Member] | Purchase Orders and Commitment [Member]
Loss Contingencies [Line Items]
Contractual obligation			5,600		5,600
Keno Hill [Member] | Purchase Orders and Commitment [Member]
Loss Contingencies [Line Items]
Contractual obligation			7,100		7,100
Casa Berardi [Member] | Purchase Orders and Commitment [Member]
Loss Contingencies [Line Items]
Contractual obligation			8,000		8,000
Other [Member] | Purchase Orders and Commitment [Member]
Loss Contingencies [Line Items]
Contractual obligation			$ 5,000		$ 5,000
Johnny M Mine Area near San Mateo, New Mexico [Member]
Loss Contingencies [Line Items]
Estimated response costs	$ 9,600
Carpenter Snow Creek Superfund Site, Cascade County, Montana [Member]
Loss Contingencies [Line Items]
Estimated response costs		$ 4,500
Estimated future response cost		$ 100,000