Note 10 - Commitments, Contingencies, and Obligations (Details Textual) - USD ($) $ in Thousands	1 Months Ended			3 Months Ended
	Jul. 31, 2018	Aug. 31, 2012	Jun. 30, 2011	Mar. 31, 2021	Mar. 31, 2022
Finance Lease, Liability, to be Paid, Total					$ 15,502
Lessee, Operating Lease, Liability, to be Paid, Total					14,938
Lease Commitments [Member]
Finance Lease, Liability, to be Paid, Total					15,500
Lessee, Operating Lease, Liability, to be Paid, Total					14,900
Performance Obligation Commitments [Member]
Surety Bonds					183,500
Letters of Credit Outstanding, Amount					17,300
Purchase Orders and Commitment [Member] | Greens Creek [Member]
Contractual Obligation, Total					7,700
Purchase Orders and Commitment [Member] | Lucky Friday [Member]
Contractual Obligation, Total					10,100
Purchase Orders and Commitment [Member] | Casa Berardi [Member]
Contractual Obligation, Total					200
Purchase Orders and Commitment [Member] | Nevada Operations [Member]
Contractual Obligation, Total					$ 4,600
Johnny M Mine Area near San Mateo, New Mexico [Member]
Payment Of Response Costs		$ 1,100
Estimated Response Costs	$ 9,600			$ 9,000
Environmental Remediation Expense				9,000
Johnny M Mine Area near San Mateo, New Mexico [Member] | Environmental Remediation, Past Response Costs [Member]
Accrual for Environmental Loss Contingencies, Period Increase (Decrease), Total				$ 2,900
Carpenter Snow Creek Superfund Site, Cascade County, Montana [Member]
Estimated Response Costs			$ 4,500
Estimated Future Response Cost			$ 100,000