Geographic and Segment Information - Schedule of Segment Reporting Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Net property, plant and equipment	$ 26,346		$ 26,346		$ 35,409
Restricted cash	3,668		3,668		3,668
Notes receivable, non-current	1,242		1,242		3,328
Mineral property expenses	969	$ 1,552	1,751	$ 2,321
General and administrative expenses	2,054	1,608	3,859	3,276
Acquisition costs	422		(333)
Accretion of asset retirement costs	134	131	268	263	1,039
Impairment of uranium properties	(17,968)		(17,968)
Depreciation and amortization	33	39	67	77
Total operating expenses	(20,736)	(3,330)	(24,246)	(5,937)
Other income	279	691	370	5,142
Long Term Assets [Member]
Net property, plant and equipment	26,346		26,346		35,409
Restricted cash	3,668		3,668		3,668
Notes receivable, non-current	1,242		1,242		3,328
Total long-term assets	31,256		31,256		42,405
Operating Results [Member]
Mineral property expenses	969	1,552	1,751	2,321
General and administrative expenses	2,054	1,608	3,859	3,276
Acquisition costs	(422)		333
Accretion of asset retirement costs	134	131	268	263
Impairment of uranium properties	17,968		17,968
Depreciation and amortization	33	39	67	77
Total operating expenses	20,736	3,330	24,246	5,937
Loss from operations	(20,736)	(3,330)	(24,246)	(5,937)
Other income	279	691	370	5,142
Loss before taxes	(20,457)	(2,639)	(23,876)	(795)
Corporate [Member] | Long Term Assets [Member]
Net property, plant and equipment	187		187		211
Restricted cash
Notes receivable, non-current					834
Total long-term assets	187		187		1,045
Corporate [Member] | Operating Results [Member]
Mineral property expenses
General and administrative expenses	1,364	1,207	2,717	2,519
Acquisition costs	(422)		333
Accretion of asset retirement costs
Impairment of uranium properties
Depreciation and amortization	1		2	1
Total operating expenses	943	1,207	3,052	2,520
Loss from operations	(943)	(1,207)	(3,052)	(2,520)
Other income	172	239	253	199
Loss before taxes	(771)	(968)	(2,799)	(2,321)
Uranium [Member] | Long Term Assets [Member]
Net property, plant and equipment	17,186		17,186		35,198
Restricted cash	3,668		3,668		3,668
Notes receivable, non-current	1,242		1,242		2,494
Total long-term assets	22,096		22,096		41,360
Uranium [Member] | Operating Results [Member]
Mineral property expenses	830	1,323	1,604	1,971
General and administrative expenses	453	401	905	757
Acquisition costs
Accretion of asset retirement costs	134	131	268	263
Impairment of uranium properties	17,968		17,968
Depreciation and amortization	31	39	64	76
Total operating expenses	19,416	1,894	20,809	3,067
Loss from operations	(19,416)	(1,894)	(20,809)	(3,067)
Other income	107	452	117	4,943
Loss before taxes	(19,309)	(1,442)	(20,692)	1,876
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	130	229	138	350
General and administrative expenses
Acquisition costs
Accretion of asset retirement costs
Impairment of uranium properties
Depreciation and amortization
Total operating expenses	130	229	138	350
Loss from operations	(130)	(229)	(138)	(350)
Other income
Loss before taxes	(130)	(229)	(138)	(350)
Graphite [Member] | Long Term Assets [Member]
Net property, plant and equipment	8,973		8,973
Restricted cash
Notes receivable, non-current
Total long-term assets	8,973		8,973
Graphite [Member] | Operating Results [Member]
Mineral property expenses	9		9
General and administrative expenses	237		237
Acquisition costs
Accretion of asset retirement costs
Impairment of uranium properties
Depreciation and amortization	1		1
Total operating expenses	247		247
Loss from operations	(247)		(247)
Other income
Loss before taxes	$ (247)		$ (247)