Note 15 - Commitments, Contingencies, and Obligations (Details Textual) - USD ($) $ in Thousands	1 Months Ended				3 Months Ended	12 Months Ended
	Jul. 31, 2018	Dec. 31, 2014	Aug. 31, 2012	Jun. 30, 2011	Mar. 31, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Environmental Remediation Expense						$ 14,571	$ 3,929	$ 4,690
Finance Lease, Liability, Payment, Due, Total						14,231
Lessee, Operating Lease, Liability, to be Paid, Total						15,783
Lease Commitments [Member]
Finance Lease, Liability, Payment, Due, Total						14,200
Lessee, Operating Lease, Liability, to be Paid, Total						15,800
Performance Obligation Commitments [Member]
Surety Bonds						182,500
Letters of Credit Outstanding, Amount						17,300
Lucky Friday [Member] | Purchase Orders and Commitment [Member]
Contractual Obligation, Total						10,200
Casa Berardi [Member] | Purchase Orders and Commitment [Member]
Contractual Obligation, Total						100
Greens Creek [Member] | Purchase Orders and Commitment [Member]
Contractual Obligation, Total						4,800
Nevada Operations [Member] | Purchase Orders and Commitment [Member]
Contractual Obligation, Total						$ 3,800
Johnny M Mine Area near San Mateo, New Mexico [Member]
Payment Of Response Costs		$ 1,100	$ 1,100
Estimated Response Costs	$ 9,600				$ 9,000		$ 6,100
Environmental Remediation Expense					$ 9,000
Carpenter Snow Creek Superfund Site, Cascade County, Montana [Member]
Estimated Response Costs				$ 4,500
Estimated Future Response Cost				$ 100,000