Mineral Property Expenditures - Schedule of Minerals Property Expenditures (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Total restoration/recovery expenses	$ 14	$ 131	$ 57	$ 485
Total standby care and maintenance expenses	371	$ 323	1,048	$ 1,005
Exploration and evaluation costs	193		599
Land maintenance and holding costs	342	$ 533	1,317	$ 1,439
Mineral property expenses	$ 920	$ 987	$ 3,021	2,929
Kingsville Dome Project [Member]
Total restoration/recovery expenses				328
Total standby care and maintenance expenses	$ 153	$ 210	$ 433	502
Rosita Project [Member]
Total restoration/recovery expenses	14	131	57	131
Total standby care and maintenance expenses	$ 113	$ 20	$ 301	258
Vasquez Project [Member]
Total restoration/recovery expenses				26
Total standby care and maintenance expenses	$ 105	$ 93	$ 314	$ 245