Asset Retirement Obligations (Schedule Of Asset Retirement Obligations) (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013
Asset Retirement Obligation Disclosure [Abstract]
ARO liability, January 1:	$ 133,657		$ 146,159
Accretion of discount	3,538		4,152
Liability incurred	2,889		3,820
Liability settled	(3,936)		(3,439)
Liability sold	(1,206)		(632)
Revision of estimates	(38,263)	[1]	(16,166)	[1]
ARO liability, September 30:	96,679		133,894
Less current portion	2,718		2,954
Total long-term ARO	$ 93,961		$ 130,940

[1] Plugging liability estimates were revised in both 2014 and 2013 for updates in the cost of services used to plug wells over the preceding year. We had various upward and downward adjustments.