Derivative Financial Instruments - Changes in Fair Value and Settlements of Commodity Derivative Contracts (Details) - USD ($) $ in Thousands |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2017 |
Jun. 30, 2016 |
Jun. 30, 2017 |
Jun. 30, 2016 |
|
| Gain Loss On Derivative Instruments Net Pretax [Abstract] | ||||
| Derivative (gain) loss | $ (3,689) | $ 4,942 | $ (7,644) | $ 2,449 |
| X | ||||||||||
- Definition Aggregate net gain (loss) on all derivative instruments recognized in earnings during the period, before tax effects. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- References No definition available.
|