Segment Information (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($) Segment	Jun. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | Segment			2
Segment Reporting Information, Results of operations [Abstract]
Total interest expense	$ 56	$ 130	$ 145	$ 214
Operating income (loss) from identified segments	(5,927)	769	(29,446)	1,396
General and administrative expenses	(1,221)	(1,533)	(2,700)	(3,139)
Add back Interest expenses	56	130	145	214
Other revenues and expenses	(353)	(713)	(537)	(1,090)
Income (loss) before income taxes	(6,280)	56	(29,983)	306
Depreciation depletion and amortization expense [Abstract]
Total depreciation depletion amortization expense	2,122	3,651	5,063	7,013
Assets by segment [Abstract]
Total Assets	95,418		95,418		$ 123,523
Reportable Segment [Member]
Segment Reporting Information, Results of operations [Abstract]
Total revenues	3,285	9,128	5,964	17,384
Total operating expenses	7,991	6,826	32,710	12,849
Total interest expense	56	130	145	214
Operating income (loss) from identified segments	(4,762)	2,172	(26,891)	4,321
Add back Interest expenses	56	130	145	214
Reportable Segment [Member] | Oil and gas [Member]
Segment Reporting Information, Results of operations [Abstract]
Total revenues	3,285	9,128	5,964	17,384
Total operating expenses	7,284	6,169	31,250	11,435
Total interest expense	56	130	145	214
Operating income (loss) from identified segments	(4,055)	2,829	(25,431)	5,735
Add back Interest expenses	56	130	145	214
Depreciation depletion and amortization expense [Abstract]
Total depreciation depletion amortization expense	2,055	3,583	4,929	6,877
Assets by segment [Abstract]
Total Assets	66,291		66,291		92,020
Reportable Segment [Member] | Mineral properties [Member]
Segment Reporting Information, Results of operations [Abstract]
Total operating expenses	707	657	1,460	1,414
Total interest expense	0	0	0	0
Operating income (loss) from identified segments	(707)	(657)	(1,460)	(1,414)
Add back Interest expenses	0	0	0	0
Depreciation depletion and amortization expense [Abstract]
Total depreciation depletion amortization expense	31	30	62	61
Assets by segment [Abstract]
Total Assets	21,944		21,944		21,942
Corporate, Non-Segment [Member]
Depreciation depletion and amortization expense [Abstract]
Total depreciation depletion amortization expense	36	$ 38	72	$ 75
Assets by segment [Abstract]
Total Assets	$ 7,183		$ 7,183		$ 9,561