Asset Retirement Obligations (Schedule Of Asset Retirement Obligations) (Details) - USD ($) $ in Thousands		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019
Asset Retirement Obligation Disclosure [Abstract]
ARO liability, January 1:		$ 66,627	$ 64,208
Accretion of discount		(1,169)	(1,168)
Liability incurred		460	3,656
Liability settled		(435)	(2,316)
Liability sold		(463)	(1,632)
Revision of estimates	[1]	(3,110)	2,349
ARO liability, June 30:		64,248	67,433
Less: current portion		1,104	1,784
Total long-term ARO		$ 63,144	$ 65,649

[1] Plugging liability estimates were revised in both 2020 and 2019 for updates in the cost of services used to plug wells over the preceding year. We had various upward and downward adjustments.