Derivative Financial Instruments and Fair Value of Financial Instruments (Details 1) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Prepaid expenses and other [Member]
Fair value of the derivative instruments
Derivative Asset, Fair Value	$ 769	$ 814
Accrued liabilities and other [Member]
Fair value of the derivative instruments
Derivative Asset, Fair Value	3,856	7,196
Other long-term liabilities [Member]
Fair value of the derivative instruments
Derivative Asset, Fair Value	10,335	14,669
Current portion of royalty obligation [Member]
Fair value of the derivative instruments
Derivative Asset, Fair Value	38,476	37,206
Non-current portion of royalty obligation [Member]
Fair value of the derivative instruments
Derivative Asset, Fair Value	108,238	122,194
Silver ounces received from Mandalay [Member]
Fair value of the derivative instruments
Derivative Asset, Fair Value	562	814
Silver ounces received from Mandalay [Member] | Prepaid expenses and other [Member]
Fair value of the derivative instruments
Derivative Asset, Fair Value	562	814
Silver ounces received from Mandalay [Member] | Accrued liabilities and other [Member]
Fair value of the derivative instruments
Derivative Asset, Fair Value
Silver ounces received from Mandalay [Member] | Other long-term liabilities [Member]
Fair value of the derivative instruments
Derivative Asset, Fair Value
Silver ounces received from Mandalay [Member] | Current portion of royalty obligation [Member]
Fair value of the derivative instruments
Derivative Asset, Fair Value
Silver ounces received from Mandalay [Member] | Non-current portion of royalty obligation [Member]
Fair value of the derivative instruments
Derivative Asset, Fair Value
Forward foreign exchange contracts [Member] | Prepaid expenses and other [Member]
Fair value of the derivative instruments
Derivative Liability, Fair Value	167
Forward foreign exchange contracts [Member] | Accrued liabilities and other [Member]
Fair value of the derivative instruments
Derivative Liability, Fair Value	581	3,188
Forward foreign exchange contracts [Member] | Other long-term liabilities [Member]
Fair value of the derivative instruments
Derivative Liability, Fair Value
Forward foreign exchange contracts [Member] | Current portion of royalty obligation [Member]
Fair value of the derivative instruments
Derivative Liability, Fair Value
Forward foreign exchange contracts [Member] | Non-current portion of royalty obligation [Member]
Fair value of the derivative instruments
Derivative Liability, Fair Value
Palmarejo gold production royalty [Member] | Prepaid expenses and other [Member]
Fair value of the derivative instruments
Derivative Liability, Fair Value
Palmarejo gold production royalty [Member] | Accrued liabilities and other [Member]
Fair value of the derivative instruments
Derivative Liability, Fair Value
Palmarejo gold production royalty [Member] | Other long-term liabilities [Member]
Fair value of the derivative instruments
Derivative Liability, Fair Value
Palmarejo gold production royalty [Member] | Current portion of royalty obligation [Member]
Fair value of the derivative instruments
Derivative Liability, Fair Value	38,476	37,206
Palmarejo gold production royalty [Member] | Non-current portion of royalty obligation [Member]
Fair value of the derivative instruments
Derivative Liability, Fair Value	108,238	122,194
Put and call options, net [Member] | Prepaid expenses and other [Member]
Fair value of the derivative instruments
Derivative Liability, Fair Value
Put and call options, net [Member] | Accrued liabilities and other [Member]
Fair value of the derivative instruments
Derivative Liability, Fair Value	2,858	3,183
Put and call options, net [Member] | Other long-term liabilities [Member]
Fair value of the derivative instruments
Derivative Liability, Fair Value	10,335	14,669
Put and call options, net [Member] | Current portion of royalty obligation [Member]
Fair value of the derivative instruments
Derivative Liability, Fair Value
Put and call options, net [Member] | Non-current portion of royalty obligation [Member]
Fair value of the derivative instruments
Derivative Liability, Fair Value
Concentrate sales contracts [Member] | Prepaid expenses and other [Member]
Fair value of the derivative instruments
Derivative Asset, Fair Value	40
Concentrate sales contracts [Member] | Accrued liabilities and other [Member]
Fair value of the derivative instruments
Derivative Asset, Fair Value	417	825
Concentrate sales contracts [Member] | Other long-term liabilities [Member]
Fair value of the derivative instruments
Derivative Asset, Fair Value
Concentrate sales contracts [Member] | Current portion of royalty obligation [Member]
Fair value of the derivative instruments
Derivative Asset, Fair Value
Concentrate sales contracts [Member] | Non-current portion of royalty obligation [Member]
Fair value of the derivative instruments
Derivative Asset, Fair Value