Note 8 - Shareholders' Equity (Detail) (USD $)	3 Months Ended	8 Months Ended		0 Months Ended	3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	May 07, 2013	May 08, 2012 Common Stock [Member]	Mar. 31, 2013 Minimum [Member]
Common Stock, Dividends, Per Share, Declared (in Dollars per share)	$ 0.0025
Dividends, Common Stock	$ 0.7
Average Realized Silver Price	28.86				30
Average Realized Silver Price	28.86				30
Stock Repurchase Program, Authorized Amount				20,000,000
Stock Repurchased During Period, Shares (in Shares)		400,300
Accelerated Share Repurchases, Final Price Paid Per Share (in Dollars per share)		$ 5.56
Stock Repurchase Program, Remaining Authorized Repurchase Amount		$ 19,600,000
Sale of Stock, Price Per Share (in Dollars per share)			$ 3.26