Property And Equipment, Net (Schedule Of Property And Equipment) (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Proved properties	$ 3,550,822	$ 3,174,268
Accumulated depreciation, depletion and amortization	(1,238,775)	(1,087,541)
Proved properties, net	2,312,047	2,086,727
Unproved properties, not being amortized
Unevaluated leasehold and seismic costs	382,953	401,954
Exploratory wells in progress	59,485	71,402
Capitalized interest	62,208	61,841
Total unproved properties, not being amortized	504,646	535,197
Other property and equipment	17,190	16,017
Accumulated depreciation	(9,438)	(8,688)
Other property and equipment, net	7,752	7,329
Total property and equipment, net	$ 2,824,445	$ 2,629,253