Income and Mining Taxes (Details 5) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Income Tax Examination [Line Items]
Valuation allowance	$ 409,883	$ 289,378
United States [Member]
Income Tax Examination [Line Items]
Valuation allowance	305,534	236,653
Argentina [Member]
Income Tax Examination [Line Items]
Valuation allowance	21,520	17,005
Canada [Member]
Income Tax Examination [Line Items]
Valuation allowance	2,009	4,453
Bolivia [Member]
Income Tax Examination [Line Items]
Valuation allowance	15,948	0
Mexico [Member]
Income Tax Examination [Line Items]
Valuation allowance	33,189	0
New Zealand [Members]
Income Tax Examination [Line Items]
Valuation allowance	28,710	27,292
Other [Member]
Income Tax Examination [Line Items]
Valuation allowance	$ 2,973	$ 3,975