Property, Plant And Equipment (Schedule Of Property, Plant And Equipment) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Property, Plant and Equipment [Abstract]
Subject to depletion	$ 5,654,672	$ 5,687,557
Unevaluated costs	230,719	221,605
Net oil and gas properties	601,657	640,443
Pipelines and processing facilities	340,618	347,093
General properties	71,720	72,125
Accumulated depletion	(5,283,734)	(5,268,719)
Accumulated depreciation	(198,664)	(198,856)
Net other property and equipment	213,674	220,362
Property, plant and equipment, net of accumulated depletion and depreciation	$ 815,331	$ 860,805