Note 4 - Commitments, Contingencies and Obligations (Details Textual)						1 Months Ended		3 Months Ended	6 Months Ended	12 Months Ended	27 Months Ended
	Jun. 30, 2016 USD ($)	Apr. 26, 2016	Apr. 15, 2016 USD ($)	Dec. 11, 2013 USD ($)	Apr. 12, 2013 USD ($)	Aug. 31, 2012 USD ($)	Jun. 30, 2011 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2016 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 1980
Joint Venture [Member] | Rio Grande Silver Inc and Emerald Mining and Leasing LLC [Member]
Liability for Remediation									$ 0
Equity Method Investment, Ownership Percentage	70.00%								70.00%
Maximum Environmental Remediation Obligation									$ 2,500,000
Carpenter Snow Creek Superfund Site, Cascade County, Montana [Member]
Number of Mining Claims												6
Estimated Response Costs							$ 4,500,000
Estimated Future Response Cost							$ 100,000,000
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
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
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]
Liability for Remediation			$ 9,900,000					$ 9,900,000
Loss Contingency, Estimate of Possible Loss	3,900,000								$ 3,900,000
Number of Days for Obligation to Pay									60 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	1,100,000								1,100,000
Noncapital Costs									600,000
Casa Berardi [Member]
Open Purchase Orders	1,900,000								1,900,000
Noncapital Costs									1,200,000
Greens Creek [Member]
Open Purchase Orders	7,200,000								7,200,000
Noncapital Costs									2,800,000
Revett Mining Company, Inc. [Member]
Business Combination, Consideration Held for Reclamation	6,500,000								6,500,000
Number of Days for Public Comment		30 days
Loss Contingency, Estimate of Possible Loss				$ 1,000,000
Contractual Obligations	1,200,000								1,200,000
Commitments For Capital Lease Payments	15,400,000								15,400,000
Surety Bonds	$ 111,200,000								$ 111,200,000
Loss Contingency, Number of Plaintiffs				4