Note 4 - Commitments, Contingencies and Obligations (Details Textual)				1 Months Ended			3 Months Ended	9 Months Ended	12 Months Ended	27 Months Ended
	Nov. 07, 2016 USD ($)	Dec. 11, 2013 USD ($)	Apr. 12, 2013 USD ($)	Aug. 31, 2016 USD ($)	Aug. 31, 2012 USD ($)	Jun. 30, 2011 USD ($)	Jun. 30, 2015 USD ($)	Sep. 30, 2016 USD ($)	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]
Equity Method Investment, Ownership Percentage								70.00%
Maximum Environmental Remediation Obligation								$ 2,500,000
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]
Payment Of Response Costs					$ 1,100,000					$ 1,100,000
Estimated Response Costs								5,600,000
Liability for Remediation								5,600,000
Carpenter Snow Creek Superfund Site, Cascade County, Montana [Member]
Estimated Response Costs						$ 4,500,000
Estimated Future Response Cost						$ 100,000,000
Number of Mining Claims											6
Gilt Edge Mine Superfund Site [Member] | Costs Incurred by the EPA [Member]
Incurred Response Costs								118,000,000
Gilt Edge Mine Superfund Site [Member] | United States and South Dakota [Member] | Subsequent Event [Member] | Insurance Companies and Another PRP [Member]
Loss Contingency Accrual, Payments	$ 6,400,000
Gilt Edge Mine Superfund Site [Member] | United States and South Dakota [Member] | Subsequent Event [Member]
Loss Contingency Accrual, Payments	$ 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] | United States and Colorado [Member]
Loss Contingency Accrual, Payments				$ 6,000,000
Gilt Edge Site and Nelson Tunnel/Commodore Site [Member]
Liability for Remediation							$ 9,900,000
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								1,400,000
Noncapital Costs								600,000
Casa Berardi [Member]
Open Purchase Orders								1,600,000
Noncapital Costs								1,100,000
Greens Creek [Member]
Open Purchase Orders								8,300,000
Noncapital Costs								2,400,000
Contractual Obligations								800,000
Commitments For Capital Lease Payments								14,200,000
Surety Bonds								$ 105,300,000
Loss Contingency, Number of Plaintiffs		4
Loss Contingency, Estimate of Possible Loss		$ 1,000,000