Supplemental Disclosures (Details 1) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Supplemental disclosures of cash flow information
Cash paid for interest expense, net of amounts capitalized	$ 5,269	$ 5,801	$ 780
Asset retirement obligations related to mineral properties	3,843	1,363	1,195
Asset retirement obligations related to support equipment and facilities	120	3	49
Increase in liabilities for oil and natural gas properties capital expenditures	32,972	7,458	24,847
Increase in liabilities for support equipment and facilities	4,290	660	1,112
Issuance of restricted stock units for Board and advisor services	444	274	73
Issuance of common stock for Board and advisor services	16	57	71
(Decrease) increase in liabilities for accrued cost to issue equity	0	0	(332)
Stock based compensation expense recognized as liability	223	1,012	(1,092)
Transfer of inventory to oil and natural gas properties	$ 216	$ 343	$ 69