Summary of Significant Accounting Policies (Details Textual) (USD $)	3 Months Ended	12 Months Ended				15 Months Ended
	Mar. 31, 2011 oz	Dec. 31, 2012 oz	Dec. 31, 2011 oz	Dec. 31, 2011 oz	Dec. 31, 2010	Dec. 31, 2012 oz
Summary of Significant Accounting Policies (Textual) [Abstract]
Minimum Voting control		50.00%
Investments in Equity Method		0.00%
Ownership Interest in equity Method		50.00%
Investments in corporate joint ventures under the equity Method		50.00%
Investments in Cost Method		0.00%
Ownership Interest in Cost Method		20.00%
Third-party smelting and refining costs recorded as a reduction of revenue		$ 16,600,000		$ 17,700,000	$ 8,600,000
Company outstanding provisionally priced sales			22,500,000	22,500,000
Outstanding Provisionally Priced Sales Consists of Silver		400,000	200,000	200,000		400,000
Outstanding Provisionally Priced Sales Consists of Gold		11,957	9,701	9,701		11,957
Fair Value of Gold and Silver Including Embedded Derivative		34,100	21,700,000	21,700,000		34,100
Consisting ounces of silver			200,000,000	200,000,000
Fair value of embedded derivative			21,700,000	21,700,000
Each one cent per ounce change in realized silver price, revenue would vary (plus or minus)		4,000	2,000,000	2,000,000		4,000
Each one dollar per ounce change in realized gold price, revenue would vary (plus or minus)		12,000	9,700,000	9,700,000		12,000
Maturity of cash and cash equivalents include all highly-liquid investments			three months
Reported ore on the leach pads, total assets		0	0	0		0
Reported ore on the leach pads, current assets		22,991,000	27,252,000	27,252,000		22,991,000
Reported ore on the leach pads, non-current assets		0	0	0		0
Decrease in estimated silver ounces inventory	700,000			500,000		200,000
Decrease in estimated gold ounces inventory	298		8,879			10,828
Drilling and related costs		0	0	0		0
Impairment of Long-Lived Assets Held-for-use		5,825,000		0	0
Maturity Period of Certificates of Deposits		three months to a year
Restricted Cash and Cash Equivalents, Noncurrent		24,970,000	28,911,000	28,911,000		24,970,000
Certificates of deposit and cash			0	0
Tax Year 2009 [Member] | Foreign Tax Authority [Member]
Significant Accounting Policies [Line Items]
Income tax expense, additional expense recognized		1.4
Tax Year 2010 and 2011 [Member] | Foreign Tax Authority [Member]
Significant Accounting Policies [Line Items]
Income tax expense, additional expense recognized		$ 15.5