Cost Of Sales (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Cost of Revenue [Abstract]
Mining operations costs	$ 98,885	$ 82,621	$ 199,734	$ 171,100
Operations costs to metal inventory	(7,830)	2,231	(11,280)	(459)
Mining related depreciation and amortization	25,110	15,490	44,153	36,519
Accretion of asset retirement obligations	705	2,183	1,408	3,116
Total cost of sales	$ 116,870	$ 102,525	$ 234,015	$ 210,276