Property, Plant and Equipment and Assets Held for Sale (Details 2) (USD $)	3 Months Ended	6 Months Ended			3 Months Ended		0 Months Ended	1 Months Ended	3 Months Ended	6 Months Ended					3 Months Ended				3 Months Ended								3 Months Ended				3 Months Ended				3 Months Ended
	Jun. 30, 2013	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012	Jun. 30, 2013 Velardena Operations	Jun. 30, 2013 San Diego exploration property	Feb. 28, 2013 Peruvian exploration properties	Feb. 28, 2013 Peruvian exploration properties	Mar. 31, 2013 Peruvian exploration properties	Jun. 30, 2013 Peruvian exploration properties	Dec. 31, 2012 Peruvian exploration properties	Jun. 30, 2013 Mineral properties	Mar. 31, 2013 Mineral properties	Dec. 31, 2012 Mineral properties	Jun. 30, 2013 Mineral properties Velardena Operations	Jun. 30, 2013 Exploration properties	Mar. 31, 2013 Exploration properties	Dec. 31, 2012 Exploration properties	Jun. 30, 2013 Exploration properties Velardena Operations	Jun. 30, 2013 Exploration properties San Diego exploration property	Jun. 30, 2013 Royalty properties	Mar. 31, 2013 Royalty properties	Dec. 31, 2012 Royalty properties	Jun. 30, 2013 Buildings	Mar. 31, 2013 Buildings	Dec. 31, 2012 Buildings	Jun. 30, 2013 Buildings Velardena Operations	Jun. 30, 2013 Mining equipment and machinery	Mar. 31, 2013 Mining equipment and machinery	Dec. 31, 2012 Mining equipment and machinery	Jun. 30, 2013 Mining equipment and machinery Velardena Operations	Jun. 30, 2013 Other furniture and equipment	Mar. 31, 2013 Other furniture and equipment	Dec. 31, 2012 Other furniture and equipment	Jun. 30, 2013 Other furniture and equipment Velardena Operations	Jun. 30, 2013 Asset retirement cost	Mar. 31, 2013 Asset retirement cost	Dec. 31, 2012 Asset retirement cost
Property, Plant and Equipment [Line Items]
Gross Value Prior to Impairment	$ 294,831,000	$ 293,165,000										$ 27,591,000	$ 239,200,000	$ 239,200,000		$ 3,724,000	$ 15,624,000	$ 15,685,000			$ 200,000	$ 200,000	$ 200,000	$ 2,349,000	$ 5,385,000	$ 4,808,000		$ 19,695,000	$ 30,271,000	$ 29,185,000		$ 1,164,000	$ 2,064,000	$ 2,204,000		$ 2,087,000	$ 2,087,000	$ 1,883,000
Impairment Charges	238,020,000	238,020,000			229,593,000	8,428,000									211,609,000				3,472,000	8,428,000							3,036,000				10,576,000				900,000
Gross Value After Impairment	56,810,000	56,810,000										27,591,000	239,200,000	239,200,000		3,724,000	15,624,000	15,685,000			200,000	200,000	200,000	2,349,000	5,385,000	4,808,000		19,695,000	30,271,000	29,185,000		1,164,000	2,064,000	2,204,000		2,087,000	2,087,000	1,883,000
Assets Held for Sale
Carrying value of the properties in assets held for sale				575,000							600,000
Amount of an agreement to sell exploration concessions								4,300,000
Net proceeds from sale of exploration concessions		3,842,000	2,494,000						3,500,000
Amount of an agreement to sell exploration concessions conditioned on the receipt of third party consents							800,000			600,000
Gain on the sale of the properties										$ 2,900,000