Inventory (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Current:
Concentrate stockpiles	$ 6,393,000	$ 3,704,000
Raw materials	95,248,000	44,770,000
Work in process	55,229,000	16,602,000
Finished goods	114,903,000	45,045,000
Materials and supplies	15,603,000	1,822,000
Total current	287,376,000	111,943,000
Long-term:
Concentrate stockpiles	4,000	1,144,000
Raw materials	26,092,000	3,186,000
Finished goods	0	32,000
Total long-term	26,096,000	4,362,000
Production costs expensed that would have been allocated to additional tons produced, assuming operations at normal production rates	12,000,000	4,300,000	11,000,000
Write-down of inventory as a result of production or purchase costs in excess of net realizable value	80,900,000	2,800,000	2,500,000
Write-down of work-in-process inventory and stockpile based on estimated REO quantities	$ 2,100,000	$ 2,300,000	$ 2,700,000