Discontinued Operations (Details) (USD $) In Thousands, unless otherwise specified	8 Months Ended	12 Months Ended
	Aug. 31, 2010	Dec. 31, 2010	Dec. 31, 2009
Financial information included in income from discontinued operations
Sales of metal			$ 12,108
Production costs applicable to sales			(2,863)
Depreciation and depletion			(5,765)
Administrative and general			(25)
Mining exploration			(2,153)
Care and maintenance and other			(10,430)
Other income and expense			1,600
Income tax expense			(2,073)
Income from discontinued operations			(9,601)
Gain (loss) on sale of net assets of discontinued operations, net of taxes of $0.0 million for 2010 and $6.5 million for 2009		(2,095)	25,537
Total			15,936
Cerro Bayo Mine [Member]
Financial information included in income from discontinued operations
Sales of metal			1,673
Production costs applicable to sales			(1,211)
Depreciation and depletion		(2,194)	(4,195)
Administrative and general		(18)	(25)
Mining exploration			(2,153)
Care and maintenance and other		(2,351)	(10,430)
Other income and expense		(145)	1,600
Income tax expense		(1,321)	(2,309)
Income from discontinued operations		(6,029)	(17,050)
Gain (loss) on sale of net assets of discontinued operations, net of taxes of $0.0 million for 2010 and $6.5 million for 2009	2,100	(2,095)
Total		(8,124)	(17,050)
Broken Hill [Member]
Financial information included in income from discontinued operations
Sales of metal			10,435
Production costs applicable to sales			(1,652)
Depreciation and depletion			(1,570)
Income tax expense			236
Income from discontinued operations			7,449
Gain (loss) on sale of net assets of discontinued operations, net of taxes of $0.0 million for 2010 and $6.5 million for 2009			25,537
Total			$ 32,986