Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statements of Operations [Abstract]
General and administrative	$ 6,360	$ 6,043	$ 6,664
Impairment of unproved oil and gas properties	30,906
Other	2,214	2,744	2,227
Loss from operations	(39,480)	(8,787)	(8,891)
Other income (expense), net
(Loss), gain on derivative liability	1,521	(971)	731
Other income, net		10	43
Foreign exchange gain, (loss)	(133)	152	(6)
Financial (expenses), net	(419)	(393)	(390)
Loss before income taxes	(38,511)	(9,989)	(8,513)
Income taxes
Net loss	$ (38,511)	$ (9,989)	$ (8,513)
Net loss per share of common stock - basic and diluted (in US$)	$ (0.63)	$ (0.20)	$ (0.21)
Weighted-average shares outstanding-basic and diluted (in thousands)	61,107	50,593	41,238