Property And Equipment (Schedule Of Property And Equipment) (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Property, Plant and Equipment [Abstract]
Oil and natural gas properties	$ 5,686,188	$ 5,424,342
Office furniture and fixtures	13,139	12,589
Building	31,301	16,915
Land	3,667	3,667
Total property and equipment	5,734,295	5,457,513
Accumulated depletion, depreciation, amortization and impairment	(3,339,087)	(2,829,110)
Property and equipment, net	$ 2,395,208	$ 2,628,403