Asset Retirement Obligations (Details) $ in Thousands |
6 Months Ended |
|---|---|
|
Jun. 30, 2018
USD ($)
| |
| Asset Retirement Obligation, Roll Forward Analysis [Roll Forward] | |
| Asset retirement obligations at January 1, 2018 | $ 12,161 |
| Liabilities acquired | 16 |
| Liabilities incurred | 670 |
| Liabilities divested and settled | (556) |
| Accretion expense | 383 |
| Revisions to estimated cash flows | (11) |
| June 30, 2018 | $ 12,663 |