Asset Retirement Obligations (Schedule Of Asset Retirement Obligations) (Details) - USD ($) $ in Thousands		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014
Asset Retirement Obligation Disclosure [Abstract]
ARO liability, January 1:		$ 100,567	$ 133,657
Accretion of discount		1,757	2,366
Liability incurred		5,986	1,900
Liability settled		(1,566)	(1,917)
Liability sold		(246)	(877)
Revision of estimates	[1]	(10,130)	(14,538)
ARO liability, June 30:		96,368	120,591
Less current portion		3,277	3,118
Total long-term ARO		$ 93,091	$ 117,473

[1] Plugging liability estimates were revised in both 2015 and 2014 to account for changes in the cost of services used to plug wells over the preceding year. We had various upward and downward adjustments.