Geographic and Segment Information - Schedule of Segment Reporting Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Net property, plant and equipment	$ 35,409	$ 46,916
Restricted cash	3,668	3,964
Notes receivable, non-current	3,328
Total long-term assets		2,123
Mineral property expenses	(4,584)	(3,248)
General and administrative	(6,614)	(7,650)
Accretion of asset retirement costs	(1,039)	(480)
Depreciation and amortization	(142)	(247)
Impairment of Uranium properties	(11,436)	(1,673)
Total operating expenses	(24,818)	(13,298)
Other income (expense)	5,530	(6,307)
Long Term Assets [Member]
Net property, plant and equipment	35,409	46,916
Restricted cash	3,668	3,964
Notes receivable, non-current	3,328	2,123
Total long-term assets	42,405	53,003
Operating Results [Member]
Mineral property expenses	4,584	3,248
General and administrative	6,614	7,650
Acquisition related expenses	1,003
Accretion of asset retirement costs	1,039	480
Depreciation and amortization	142	247
Impairment of Uranium properties	11,436	1,673
Total operating expenses	24,818	13,298
Loss from operations	(24,818)	(13,298)
Other income (expense)	5,530	(6,307)
Loss before taxes	(19,288)	(19,605)
Corporate [Member] | Long Term Assets [Member]
Net property, plant and equipment	211	141
Restricted cash
Notes receivable, non-current	834
Total long-term assets	1,045	141
Corporate [Member] | Operating Results [Member]
Mineral property expenses
General and administrative	4,783	5,573
Acquisition related expenses	1,003
Accretion of asset retirement costs
Depreciation and amortization	5	8
Impairment of Uranium properties
Total operating expenses	5,791	5,581
Loss from operations	(5,791)	(5,581)
Other income (expense)	585	(6,339)
Loss before taxes	(5,206)	(11,920)
Uranium [Member] | Long Term Assets [Member]
Net property, plant and equipment	35,198	46,775
Restricted cash	3,668	3,964
Notes receivable, non-current	2,494	2,123
Total long-term assets	41,360	52,862
Uranium [Member] | Operating Results [Member]
Mineral property expenses	3,383	2,441
General and administrative	1,831	2,077
Acquisition related expenses
Accretion of asset retirement costs	1,039	480
Depreciation and amortization	137	239
Impairment of Uranium properties	11,436	1,673
Total operating expenses	17,826	6,910
Loss from operations	(17,826)	(6,910)
Other income (expense)	4,944	32
Loss before taxes	(12,882)	(6,878)
Lithium [Member] | Long Term Assets [Member]
Net property, plant and equipment
Restricted cash
Notes receivable, non-current
Total long-term assets
Lithium [Member] | Operating Results [Member]
Mineral property expenses	1,201	807
General and administrative
Acquisition related expenses
Accretion of asset retirement costs
Depreciation and amortization
Impairment of Uranium properties
Total operating expenses	1,201	807
Loss from operations	(1,201)	(807)
Other income (expense)	1
Loss before taxes	$ (1,200)	$ (807)