Note 8. Shareholders' Equity (Detail) (USD $)	0 Months Ended	1 Months Ended				3 Months Ended				6 Months Ended			6 Months Ended	1 Months Ended	6 Months Ended		3 Months Ended	12 Months Ended
	May 08, 2012	Mar. 31, 2012	Feb. 17, 2012	Feb. 28, 2012	Jan. 31, 2011	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Aug. 06, 2012	Jun. 25, 2012 Restricted Stock Units (RSUs) [Member] June 2013 [Member]	Jun. 25, 2012 Restricted Stock Units (RSUs) [Member]	Jun. 25, 2012 2013 [Member]	Jun. 25, 2012 2014 [Member]	Mar. 31, 2012 Consent Decree [Member]	Dec. 31, 2011 Consent Decree [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in Shares)													262,934	440,735
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Total Fair Value															$ 1,900,000	$ 700,000
Stock Issued During Period, Shares, New Issues (in Shares)						77,976			42,636
Share-based Compensation										1,495,000	920,000
Stock Repurchased During Period, Shares (in Shares)						60,000				39,538
Stock Repurchased During Period, Value										200,000
Accelerated Share Repurchases, Final Price Paid Per Share (in Dollars per share)						$ 4.89				$ 4.58
Common Stock, Dividends, Per Share, Declared (in Dollars per share)	$ 0.02	$ 0.0125	$ 0.01	$ 0.0025		$ 0.02				$ 0.04
Average Realized Silver Price							36.59	31.61
Dividends, Common Stock		3,600,000				6,400,000
Minimum Dividend Threshold (in Dollars per Ounces)										30
Dividends, Cash						700,000
Stock Repurchase Program, Authorized Amount						20,000,000
Stock Repurchase Program, Remaining Authorized Repurchase Amount						19,940,000
Share Price (in Dollars per share)												$ 4.69
Conversion of Stock, Shares Converted (in Shares)					2,012,500
Debt Instrument, Convertible, Conversion Ratio					9.3773
Stock Issued During Period, Shares, Conversion of Convertible Securities (in Shares)					18,900,000
Mandatory Convertible Preferred Stock Dividend					3,300,000
Proceeds from Warrant Exercises											$ 4,838,000						$ 700,000	$ 10,500,000