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Represents the amount of estimated response costs that may be incurred.

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Represents the amount of response costs paid during the period.

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Represents the amount of surety bonds in place as of a specified date. Such surety bonds may be for the purpose of, but not limited to, financial support for future reclamation and closure costs, self-insurance, and employee benefit plans.

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Amount of minimum lease payments for capital leases.

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Amount of contractual obligation, including but not limited to, long-term debt, capital lease obligations, operating lease obligations, purchase obligations, and other commitments.

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Face (par) amount of debt instrument at time of issuance.

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Net increase or decrease in the carrying amount of the debt instrument for the period.

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Contractual interest rate for funds borrowed, under the debt agreement.

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The charge against earnings in the period for known or estimated future costs arising from requirements to perform environmental remediation activities.

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The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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The cash inflow during the period from additional borrowings in aggregate debt. Includes proceeds from short-term and long-term debt.

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Note 4 - Commitments, Contingencies and Obligations (Details Textual) $ in Millions		1 Months Ended		3 Months Ended			12 Months Ended	28 Months Ended
	Apr. 12, 2013 USD ($)	Aug. 31, 2012 USD ($)	Jun. 30, 2011 USD ($)	Mar. 31, 2018 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2014 USD ($)	Mar. 05, 2018 USD ($)	Mar. 05, 2018 CAD ($)
Environmental Remediation Expense				$ 1,262,000	$ 1,119,000
Contractual Obligation, Total				7,100,000
Capital Leases, Future Minimum Payments Due, Total				13,590,000
Surety Bonds				117,000,000
Lucky Friday [Member]
Open Purchase Orders				100,000
Casa Berardi [Member]
Open Purchase Orders				3,100,000
Greens Creek [Member]
Open Purchase Orders				3,300,000
Senior Notes [Member]
Proceeds from Issuance of Debt	$ 500,000,000
Debt Instrument, Interest Rate, Stated Percentage	6.875%
Debt Instrument, Increase (Decrease), Net, Total							$ 6,500,000
Debt Instrument, Face Amount	$ 500,000,000
Series 2018-A Senior Notes [Member]
Debt Instrument, Interest Rate, Stated Percentage									4.68%	4.68%
Debt Instrument, Face Amount									$ 30,800,000	$ 40
Debt Instrument, Issuance, Discount Rate									0.58%	0.58%
Johnny M Mine Area near San Mateo, New Mexico [Member]
Payment Of Response Costs		$ 1,100,000						$ 1,100,000
Estimated Response Costs				5,600,000
Environmental Remediation Expense						$ 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
Joint Venture [Member] \| Rio Grande Silver Inc and Emerald Mining and Leasing LLC [Member]
Equity Method Investment, Ownership Percentage				70.00%
Maximum Environmental Remediation Obligation				$ 2,500,000