FRESH START ACCOUNTING - Cumulative Impact of the Reorganization Adjustments (Details) - Exchange of Stock for Stock $ in Thousands	Feb. 28, 2017 USD ($)
Fresh-Start Adjustment [Line Items]
Gain on settlement of liabilities subject to compromise	$ 230,445
Professional and other fees paid at emergence	(10,648)
Write-off of unamortized debt issuance costs	(2,577)
Other reorganization adjustments	(1,915)
Net impact to reorganization items	215,305
Gain on sale of Appalachia Properties	213,453
Cancellation of Predecessor Company equity	1,662,282
Other adjustments to accumulated deficit	(17,165)
Net impact to accumulated deficit	$ 2,073,875