Derivative Financial Instruments Gains and Losses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Derivative Instruments, (Gain) Loss [Line Items]
Derivative settlement (gain) loss	$ (39,222)	$ 135,803	$ (21,234)
Net derivative (gain) loss	97,539	(161,832)	26,414
Oil Contracts [Member]
Derivative Instruments, (Gain) Loss [Line Items]
Derivative settlement (gain) loss	19,685	68,860	31,176
Net derivative (gain) loss	172,055	(192,002)	71,502
Gas Contracts [Member]
Derivative Instruments, (Gain) Loss [Line Items]
Derivative settlement (gain) loss	(23,008)	13,029	(87,857)
Net derivative (gain) loss	(41,205)	35,411	(76,315)
NGL Contracts [Member]
Derivative Instruments, (Gain) Loss [Line Items]
Derivative settlement (gain) loss	(35,899)	53,914	35,447
Net derivative (gain) loss	$ (33,311)	$ (5,241)	$ 31,227