SUPPLEMENTARY INFORMATION ON OIL AND NATURAL GAS ACTIVITIES (UNAUDITED) (Capitalized Costs Relating to Oil and Natural Gas Producing Activities) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	May 31, 2018	Dec. 31, 2017
Proved oil and natural gas properties	$ 410,184	$ 547,136
Unproved oil and natural gas properties	8,454	68,882
Total oil and natural gas properties	418,638	616,018
Accumulated depreciation, depletion and amortization	(12,950)
Oil and Gas Property, Successful Effort Method, Net, Total	405,688	616,018
Predecessor
Proved oil and natural gas properties		2,593,249	$ 2,567,086
Total oil and natural gas properties		2,593,249	2,567,086
Accumulated depreciation, depletion and amortization		(1,237,745)	(1,191,559)
Oil and Gas Property, Successful Effort Method, Net, Total		$ 1,355,504	$ 1,375,527
Successor
Accumulated depreciation, depletion and amortization	$ (12,950)