Supplemental Disclosures (Details 1) - USD ($) $ in Thousands |
9 Months Ended | |
|---|---|---|
Sep. 30, 2015 |
Sep. 30, 2014 |
|
| Supplemental disclosures of cash flow information | ||
| Cash paid for interest expense, net of amounts capitalized | $ 2,617 | $ 3,667 |
| Asset retirement obligations related to mineral properties | 1,487 | 3,305 |
| Asset retirement obligations related to support equipment and facilities | 89 | 132 |
| (Decrease) increase in liabilities for oil and natural gas properties capital expenditures | (30,282) | 43,692 |
| Increase in liabilities for support equipment and facilities | 2,525 | 2,488 |
| Stock-based compensation expense recognized as liability | 191 | 789 |
| Transfer of inventory from oil and natural gas properties | $ 586 | $ 300 |