Derivative Financial Instruments - Changes in Fair Value and Settlements of Commodity Derivative Contracts (Details)
$ in Thousands
|3 Months Ended|
Mar. 31, 2019
|Gain Loss On Derivative Instruments Net Pretax [Abstract]|
|Derivative loss||$ 48,886|
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