Asset Retirement Obligations (Schedule Of Asset Retirement Obligations) (Details) - USD ($) $ in Thousands			4 Months Ended	8 Months Ended
		Sep. 01, 2020	Dec. 31, 2020	Aug. 31, 2020
Asset Retirement Obligation Disclosure [Abstract]
ARO liability, Beginning Balance:		$ 38,984	$ 38,984	$ 66,627
Accretion of discount			467	1,545
Liability incurred			151	465
Liability settled			(95)	(838)
Liability sold			0	(487)
Revision of estimates	[1]		(1,758)	(28,328)
Fresh start adjustments		(14,393)
ARO liability, Ending Balance:		$ 24,591	23,356	$ 38,984
Less current portion			2,121
Total long-term ARO liability			$ 21,235

[1] Plugging liability estimates were revised in 2019 and 2020 for updates in the cost of services used to plug wells over the preceding year and estimated dates to be plugged.