Asset Retirement Obligations (Schedule Of Asset Retirement Obligations) (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020
ARO liability, Beginning Balance:		$ 23,356	$ 66,627
Accretion of discount		(461)	(596)
Liability incurred		0	314
Liability settled		(16)	(319)
Liability sold		(2)	(15)
Revision of estimates	[1]	44	(3,384)
ARO, Ending Balance:		23,843	63,819
Less: current portion		2,161	1,470
Total long-term ARO		$ 21,682	$ 62,349

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