Derivative Financial Instruments - Changes in Fair Value and Settlements of Commodity Derivative Contracts (Details) - USD ($) $ in Thousands |
3 Months Ended | 12 Months Ended | ||
|---|---|---|---|---|
Dec. 31, 2018 |
Dec. 31, 2018 |
Dec. 31, 2017 |
Dec. 31, 2016 |
|
| Gain Loss On Derivative Instruments Net Pretax [Abstract] | ||||
| Derivative (gain) loss | $ (59,700) | $ (53,798) | $ (4,199) | $ 2,926 |
| X | ||||||||||
- Definition Aggregate net gain (loss) on all derivative instruments recognized in earnings during the period, before tax effects. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
|
| X | ||||||||||
- References No definition available.
|