Note 7 - Commitments, Contingencies and Obligations (Details Textual) - USD ($)			1 Months Ended					3 Months Ended	12 Months Ended
	Oct. 30, 2019	Apr. 12, 2013	Oct. 31, 2019	Jul. 31, 2018	Dec. 31, 2014	Aug. 31, 2012	Jun. 30, 2011	Dec. 31, 2014	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2014
Environmental Remediation Expense									$ 4,690,000	$ 6,119,000	$ 6,701,000
Contractual Obligation, Total									100,000
Finance Lease, Liability, Payment, Due, Total									13,449,000
Lessee, Operating Lease, Liability, Payments, Due, Total									18,812,000
Performance Obligation Commitments [Member]
Surety Bonds									185,500,000
Letters of Credit Outstanding, Amount									33,600,000
Lucky Friday [Member]
Open Purchase Orders									1,600,000
Casa Berardi [Member]
Open Purchase Orders									300,000
Greens Creek [Member]
Open Purchase Orders									3,600,000
Nevada Operations [Member]
Open Purchase Orders									$ 800,000
Senior Notes [Member]
Proceeds from Issuance of Debt		$ 500,000,000
Debt Instrument, Increase (Decrease), Net, Total												$ 6,500,000
Canadian Assets of Klondex [Member]
Ownership Percentage				13.00%
PRP Lawsuit in Mineral County, Colorado [Member]
Loss Contingency, Damages Sought, Value	$ 5,000,000
Lawsuit filed in Ontario (Canada) Superior Court of Justice [Member] | Waterton Warrants [Member]
Class of Warrant or Right, Issued During Period, Value				$ 3,700,000
Class of Warrant or Right, Warrants Entitled, Value				8,900,000
Johnny M Mine Area near San Mateo, New Mexico [Member]
Payment Of Response Costs					$ 1,100,000	$ 1,100,000
Estimated Response Costs				$ 9,600,000	5,900,000
Environmental Remediation Expense			$ 5,900,000					$ 5,600,000
Johnny M Mine Area near San Mateo, New Mexico [Member] | Minimum [Member]
Estimated Alternative Response Costs					0
Johnny M Mine Area near San Mateo, New Mexico [Member] | Maximum [Member]
Estimated Alternative Response Costs					$ 221,000,000
Carpenter Snow Creek Superfund Site, Cascade County, Montana [Member]
Estimated Response Costs							$ 4,500,000
Estimated Future Response Cost							$ 100,000,000