Note 4 - Commitments, Contingencies and Obligations (Details Textual)						1 Months Ended		2 Months Ended	3 Months Ended			12 Months Ended
	Apr. 26, 2016	Apr. 15, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 11, 2013 USD ($)	Apr. 12, 2013 USD ($)	Aug. 31, 2012 USD ($)	Jun. 30, 2011 USD ($)	Mar. 01, 2016 USD ($)	Mar. 31, 2016 USD ($)	Jun. 30, 2015 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 1980
Joint Venture [Member] | Rio Grande Silver Inc and Emerald Mining and Leasing LLC [Member]
Equity Method Investment, Ownership Percentage			70.00%						70.00%
Maximum Environmental Remediation Obligation									$ 2,500,000
Liability for Remediation									0
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
Johnny M Mine Area near San Mateo, New Mexico [Member]
Liability for Remediation			$ 5,600,000
Payment Of Response Costs						$ 1,100,000					$ 1,100,000
Estimated Response Costs									5,600,000
Carpenter Snow Creek Superfund Site, Cascade County, Montana [Member]
Estimated Response Costs							$ 4,500,000
Number of Mining Claims													6
Estimated Future Response Cost							$ 100,000,000
Gilt Edge Mine Superfund Site [Member] | Costs Incurred by the EPA [Member]
Incurred Response Costs									118,000,000
Gilt Edge Mine Superfund Site [Member]
Liability for Remediation									3,900,000
Nelson Tunnel/Commodore Site [Member] | Costs Incurred by the EPA [Member]
Incurred Response Costs									10,000,000
Nelson Tunnel/Commodore Site [Member]
Liability for Remediation									6,000,000
Gilt Edge Site and Nelson Tunnel/Commodore Site [Member] | Subsequent Event [Member]
Liability for Remediation		$ 9,900,000
Gilt Edge Site and Nelson Tunnel/Commodore Site [Member]
Liability for Remediation										$ 9,900,000
Subsequent Event [Member]
Number of Days for Public Comment	30 days
Uncooperative Insurer [Member]
Proceeds from Lawsuit Against Uncooperative Insurer									700,000
Insurance Companies and Another PRP [Member]
Remaining Liability For Redemption									6,400,000
Senior Notes [Member]
Proceeds from Issuance of Debt					$ 500,000,000
Debt Instrument, Interest Rate, Stated Percentage					6.875%
Debt Instrument, Increase (Decrease), Net												$ 6,500,000
Lucky Friday [Member]
Open Purchase Orders			1,000,000						1,000,000
Noncapital Costs								$ 500,000
Casa Berardi [Member]
Open Purchase Orders			700,000						700,000
Noncapital Costs								3,600,000
Greens Creek [Member]
Open Purchase Orders			600,000						600,000
Noncapital Costs								2,400,000
Revett Mining Company, Inc. [Member]
Business Combination, Consideration Held for Reclamation			6,500,000						6,500,000
Contractual Obligations			11,700,000						11,700,000
Commitments For Capital Lease Payments								$ 16,300,000
Surety Bonds			$ 100,500,000						$ 100,500,000
Loss Contingency, Number of Plaintiffs				4
Loss Contingency, Estimate of Possible Loss				$ 1,000,000