Minerals Property Expenditures - Schedule of Minerals Property Expenditures (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Total restoration/recovery expenses	$ 34	$ 81	$ 43	$ 356
Total standby care and maintenance expenses	365	$ 313	676	$ 682
Exploration and evaluation costs	186		406
Land maintenance and holding costs	707	$ 668	976	$ 904
Total Mineral property expenses	$ 1,292	1,062	$ 2,101	1,942
Kingsville Dome Project [Member]
Total restoration/recovery expenses		81		329
Total standby care and maintenance expenses	$ 152	$ 157	$ 280	$ 292
Rosita Project [Member]
Total restoration/recovery expenses	34		43
Total standby care and maintenance expenses	$ 94	$ 76	$ 188	$ 237
Vasquez Project [Member]
Total restoration/recovery expenses				27
Total standby care and maintenance expenses	$ 119	$ 80	$ 208	$ 153