Derivatives (Effect Of Derivative Instruments In The Consolidated Statements Of Operations) (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		8 Months Ended	9 Months Ended
	Feb. 08, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2018	Sep. 30, 2019
Derivative Instruments, Gain (Loss) [Line Items]
Total gains (loss) on derivative contracts		$ (379)	$ (11,212)	$ (62,442)	$ (11,744)
Predecessor
Derivative Instruments, Gain (Loss) [Line Items]
Total gains (loss) on derivative contracts	$ 6,663
Derivatives Not Designated As Hedging
Derivative Instruments, Gain (Loss) [Line Items]
Total gains (loss) on derivative contracts		(379)	(11,212)	(62,442)	(11,744)
Derivatives Not Designated As Hedging | Oil
Derivative Instruments, Gain (Loss) [Line Items]
Total gains (loss) on derivative contracts		522	(12,339)	(62,995)	(16,013)
Derivatives Not Designated As Hedging | Natural gas
Derivative Instruments, Gain (Loss) [Line Items]
Total gains (loss) on derivative contracts		$ (901)	$ 1,127	$ 553	$ 4,269
Derivatives Not Designated As Hedging | Predecessor
Derivative Instruments, Gain (Loss) [Line Items]
Total gains (loss) on derivative contracts	6,663
Derivatives Not Designated As Hedging | Predecessor | Oil
Derivative Instruments, Gain (Loss) [Line Items]
Total gains (loss) on derivative contracts	4,796
Derivatives Not Designated As Hedging | Predecessor | Natural gas
Derivative Instruments, Gain (Loss) [Line Items]
Total gains (loss) on derivative contracts	$ 1,867