Asset Retirement Obligations (Schedule Of Asset Retirement Obligations) (Details) $ in Thousands		6 Months Ended
		Jun. 30, 2016 USD ($) wells	Jun. 30, 2015 USD ($)
Asset Retirement Obligation Disclosure [Abstract]
ARO liability, January 1:		$ 98,297	$ 100,567
Accretion of discount		1,513	1,757
Liability incurred		212	5,986
Liability settled		(605)	(1,566)
Liability sold	[1]	(10,308)	(246)
Revision of estimates	[2]	(18,183)	(10,130)
ARO liability, June 30:		70,926	96,368
Less current portion		3,523	3,277
Total long-term ARO		$ 67,403	$ 93,091
Wells sold | wells		1,150

[1] We sold approximately 1,150 wells to unaffiliated third-parties during the first six months of 2016.

[2] Plugging liability estimates were revised in both 2016 and 2015 for updates in the cost of services used to plug wells over the preceding year. We had various upward and downward adjustments.