Note 7 - Commitments and Contingencies (Detail) (USD $)	1 Months Ended				3 Months Ended	12 Months Ended
	Aug. 31, 2012	Jun. 30, 2011	Mar. 31, 2010	Jan. 31, 2010	Dec. 31, 2012	Dec. 31, 2012	Apr. 30, 2009
Maximum Environmental Remediation Obligation						$ 2,500,000
Loss Contingency, Estimate of Possible Loss							177,500
Payment Of Response Costs	1,100,000				1,100,000
Other Accrued Liabilities, Noncurrent					300,000	300,000
Estimated Response Costs		4,500,000	2,700,000
Estimated Future Response Cost		100,000,000		72,000,000
Incurred Response Costs			5,300,000
Contractual Obligations					3,400,000	3,400,000
Noncapital Costs						25,300,000
Commitments For Capital Lease Payments					18,400,000	18,400,000
Letters of Credit Outstanding, Amount					1,200,000	1,200,000
Greens Creek [Member]
Open Purchase Orders					4,100,000	4,100,000
Noncapital Costs						300,000
Lucky Friday [Member]
Open Purchase Orders					900,000	900,000
Noncapital Costs						500,000
Non-Capital Costs [Member]
Contractual Obligations					500,000	500,000
Minimum [Member]
Loss Contingency, Estimate of Possible Loss					0	0
Maximum [Member]
Loss Contingency, Estimate of Possible Loss					10,000,000	10,000,000
Costs Incurred By The EPA [Member]
Incurred Response Costs				$ 91,000,000