PROPERTY AND EQUIPMENT (Summary Of Property And Equipment) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
Unproved properties	$ 813,310	$ 816,282
Accumulated impairment of unproved properties	(813,310)	(742,065)
Unproved properties, net	0	74,217
Proved oil and gas properties	2,239,444	2,110,346
Accumulated depreciation, depletion, amortization and impairment	(2,024,092)	(1,421,226)
Proved oil and gas properties, net	215,352	689,120
Total oil and gas properties, net	215,352	763,337
Land	5,690	5,600
Fresh water wells	27,373	27,366
Produced water disposal system	108,966	104,498
Gas processing plant and gathering lines	414,615	380,470
Office furniture, equipment and vehicles	3,397	3,703
Accumulated depreciation and impairment	(453,013)	(77,368)
Other property and equipment, net	107,028	444,269
Total property and equipment, net	$ 322,380	$ 1,207,606