Income Taxes (Details 2) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Deferred tax liabilities:
Mineral Properties	$ 453,818	$ 450,902
Foreign subsidiaries - unremitted earnings	235,116	154,610
Property, plant and equipment, net	68,013	73,168
Deferred tax liabilities, Total	756,947	678,680
Deferred tax assets:
Net operating loss carryforwards	128,073	165,362
Foreign subsidiaries - future tax credits	133,160	61,724
Royalty and other long-term debt	48,254	51,134
Capital loss carryforwards	35,562	42,830
Asset retirement obligation	9,638	9,003
Unrealized foreign currency loss and other	3,974	4,857
Accrued expenses	23,247	19,929
Tax credit carryforwards	11,987	11,127
Inventory	6,069	3,050
Deferred tax assets, gross	399,964	269,016
Valuation allowance	(168,511)	(164,036)
Deferred tax assets, net	231,453	204,980
Net deferred tax liabilities	$ (525,494)	$ (473,700)