DIVESTITURE - Schedule of Net Gain Recognized in Sale (Details) - USD ($) $ in Thousands		1 Months Ended	2 Months Ended	3 Months Ended			10 Months Ended	12 Months Ended
	Feb. 27, 2017	Mar. 31, 2017	Feb. 28, 2017	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Transfer of asset retirement obligations							$ 81,197
Carrying value of properties sold				$ (17,275)			(17,275)
Gain (loss) on Appalachia Properties divestiture		$ 0		$ 0	$ (132)	$ 27	$ (105)
Appalachia Properties | Disposal Group, Disposed of by Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net consideration received for sale of Appalachia Properties	$ 522,500
Predecessor
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Transfer of asset retirement obligations			$ 3,641					$ 19,630	$ 72,713
Carrying value of properties sold								(26,213)
Gain (loss) on Appalachia Properties divestiture			$ 213,453					$ 0	$ 0
Predecessor | Appalachia Properties | Disposal Group, Disposed of by Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net consideration received for sale of Appalachia Properties	522,500
Release of funds held in suspense	4,139
Transfer of asset retirement obligations	8,672
Other adjustments, net	2,597
Transaction costs	(7,087)
Gain (loss) on Appalachia Properties divestiture	213,453
Predecessor | Appalachia Properties | Disposal Group, Disposed of by Sale | Oil and Gas Properties
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Carrying value of properties sold	$ (317,340)