Fair Value Measurements Fair Value Measurements (Details 1) (Portion at Other than Fair Value, Fair Value Disclosure [Member], USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Convertible Senior Notes Due March 2028 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial Liabilities Not Measured at Fair Value	$ 48,658	$ 49,205
Convertible Senior Notes Due March 2028 [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial Liabilities Not Measured at Fair Value	48,658	49,205
Convertible Senior Notes Due March 2028 [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial Liabilities Not Measured at Fair Value	0	0
Convertible Senior Notes Due March 2028 [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial Liabilities Not Measured at Fair Value	0	0
Palmarejo gold production royalty [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial Liabilities Not Measured at Fair Value	105,613	111,257
Palmarejo gold production royalty [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial Liabilities Not Measured at Fair Value	0	0
Palmarejo gold production royalty [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial Liabilities Not Measured at Fair Value	105,613	111,257
Palmarejo gold production royalty [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial Liabilities Not Measured at Fair Value	$ 0	$ 0