Segment Reporting (Details Textual) (USD $) In Thousands, unless otherwise specified	3 Months Ended							12 Months Ended
	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Segment Reporting (Textual) [Abstract]
Total Revenue	$ 343,575	$ 231,090	$ 199,624	$ 207,586	$ 118,564	$ 101,018	$ 88,289	$ 246,911	$ 1,021,200	$ 515,457	$ 300,361
Silver [Member]
Segment Reporting (Textual) [Abstract]
Total Revenue									669,800	356,900	238,400
Gold [Member]
Segment Reporting (Textual) [Abstract]
Total Revenue									$ 371,600	$ 158,500	$ 61,900