Mineral Property Expenditures - Schedule of Mineral Property Expenditures (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Total expense for the period	$ 969	$ 1,552	$ 1,751	$ 2,321
Temrezli Project, Turkey [Member]
Total expense for the period	17	24	96	123
Total Turkey Projects [Member]
Total expense for the period	17	24	96	123
Kingsville Dome Project, Texas [Member]
Total expense for the period	172	155	423	418
Rosita Project, Texas [Member]
Total expense for the period	158	172	355	284
Vasquez Project, Texas [Member]
Total expense for the period	97	114	331	283
Other Projects, Texas [Member]
Total expense for the period	(6)	1	1	2
Total Texas Projects [Member]
Total expense for the period	421	442	1,110	987
Cebolleta project, New Mexico [Member]
Total expense for the period	389	538	389	538
Juan Tafoya Project, New Mexico [Member]
Total expense for the period	3	312	9	318
Total New Mexico Projects [Member]
Total expense for the period	392	850	398	856
Columbus Basin Project, Nevada [Member]
Total expense for the period	120	74	122	191
Railroad Valley, Nevada [Member]
Total expense for the period	12	155	16	158
Total Nevada Projects [Member]
Total expense for the period	132	229	138	349
Sal Rica Project, Utah [Member]
Total expense for the period	(2)	7		6
Total Utah Projects [Member]
Total expense for the period	(2)	7		6
Coosa project, Alabama [Member]
Total expense for the period	9		9
Total Alabama Projects [Member]
Total expense for the period	$ 9		$ 9