Note 8. Shareholders' Equity (Detail) (USD $)	0 Months Ended	1 Months Ended				3 Months Ended					12 Months Ended
	May 07, 2012	Mar. 31, 2012	Feb. 17, 2012	Feb. 29, 2012	Jan. 31, 2011	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2011	Mar. 31, 2012 Consent Decree [Member]	Dec. 31, 2011 Consent Decree [Member]
Common Stock, Dividends, Per Share, Declared (in Dollars per share)	$ 0.02		$ 0.01	$ 0.0125
Average Realized Silver Price							$ 36.59	$ 31.61
Dividends, Common Stock		3,600,000				6,400,000
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									$ 4,739,000	$ 700,000	$ 10,500,000