Property and Equipment (Summary of Property and Equipment) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Unproved properties	$ 816,282
Accumulated impairment of unproved properties	(742,065)
Unproved properties, net	74,217
Proved oil and gas properties	2,110,346
Accumulated depreciation, depletion, amortization and impairment	(1,421,226)
Proved oil and gas properties, net	689,120
Total oil and gas properties, net	763,337
Land	5,059
Fresh water wells	27,366
Produced water disposal system	3,608
Office furniture, equipment and vehicles	2,840
Accumulated depreciation	(726)
Other property and equipment, net	38,147
Total property and equipment, net	$ 801,484
Predecessor
Property, Plant and Equipment [Line Items]
Unproved properties		$ 84,590
Accumulated impairment of unproved properties		0
Unproved properties, net		84,590
Proved oil and gas properties		1,061,105
Accumulated depreciation, depletion, amortization and impairment		(251,065)
Proved oil and gas properties, net		810,040
Total oil and gas properties, net		894,630
Land		2,912
Fresh water wells		0
Produced water disposal system		30,990
Office furniture, equipment and vehicles		20,008
Accumulated depreciation		(21,770)
Other property and equipment, net		32,140
Total property and equipment, net		$ 926,770