Supplemental Disclosures (Details 1) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Supplemental disclosures of cash flow information
Asset retirement obligations related to mineral properties	$ 1,978	$ 2,511
Asset retirement obligations related to support equipment and facilities	(138)	75
(Decrease) increase in liabilities for oil and natural gas properties capital expenditures	43,797	(3,476)
(Decrease) increase in liabilities for support equipment and facilities	1,838	(11,565)
Stock-based compensation expense recognized as liability	(339)	88
Increase (Decrease) in Liabilities for Accrued Cost to Issue Equity	(343)	62
Transfer of inventory from oil and natural gas properties	$ (228)	$ 474