Supplemental Disclosures (Details 1) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Supplemental disclosures of cash flow information
Cash paid for interest expense, net of amounts capitalized	$ 1,990	$ 1,269
Asset retirement obligations related to mineral properties	1,507	1,715
Asset retirement obligations related to support equipment and facilities	32	111
Increase in liabilities for oil and natural gas properties capital expenditures	8,654	42,012
Increase in liabilities for support equipment and facilities	6,865	437
Issuance of restricted stock units for Board and advisor services	142	96
Issuance of common stock for advisor services	4	6
Stock-based compensation expense recognized as liability	263	677
Transfer of inventory from oil and natural gas properties	$ 310	$ 107