REORGANIZATION - Additional Information (Details) $ / shares in Units, shares in Thousands, a in Thousands								2 Months Ended	10 Months Ended	12 Months Ended
	Mar. 01, 2017 USD ($) $ / shares shares	Feb. 28, 2017 USD ($) shares	Feb. 27, 2017 USD ($) shares	Feb. 08, 2017 USD ($)	Jan. 11, 2017 bidder	Dec. 14, 2016 USD ($)	Dec. 09, 2016 USD ($) a	Feb. 28, 2017 USD ($)	Dec. 31, 2017 USD ($) $ / shares	Dec. 31, 2017 $ / shares	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Oct. 20, 2016
Restructuring Cost and Reserve [Line Items]
Proceeds from sale of oil and gas properties, net of expenses		$ 512,472,000							$ 20,633,000
New shares issued in reorganization (in shares) | shares	20,000	20,000
Predecessor
Restructuring Cost and Reserve [Line Items]
Proceeds from sale of oil and gas properties, net of expenses								$ 505,383,000			$ 0	$ 22,839,000
Convertible Debt | Notes Due Two Thousand Seventeen
Restructuring Cost and Reserve [Line Items]
Interest rate		1.75%						1.75%
Convertible Debt | Notes Due Two Thousand Seventeen | Predecessor
Restructuring Cost and Reserve [Line Items]
Interest rate											1.75%		1.75%
Senior Notes | Notes Due Two Thousand Twenty Two
Restructuring Cost and Reserve [Line Items]
Interest rate		7.50%						7.50%					7.50%
Senior Notes | Notes Due Two Thousand Twenty Two | Predecessor
Restructuring Cost and Reserve [Line Items]
Interest rate											7.50%
Senior Notes | Second Lien Notes
Restructuring Cost and Reserve [Line Items]
Interest rate	7.50%								7.50%	7.50%
Aggregate principal amount of senior subordinated notes	$ 225,000,000
Predecessor Company's Common Stockholders
Restructuring Cost and Reserve [Line Items]
Warrants issued in reorganization (in shares) | shares	3,500
Exercise price of warrants or rights (in usd per share) | $ / shares									$ 42.04	$ 42.04
Exercise period for warrants										4 years
RSA | Predecessor
Restructuring Cost and Reserve [Line Items]
Acreage sold in agreement | a							86
Number of additional bidders allowed to participate in competitive bidding | bidder					2
RSA | TH Exploration III, LLC, an affiliate of Tug Hill, Inc. | Predecessor | Disposal Group, Disposed of by Sale
Restructuring Cost and Reserve [Line Items]
Proceeds from sale of oil and gas properties, net of expenses							$ 360,000,000
Loss on contract termination								$ 11,500,000
RSA | EQT Production Company | Predecessor | Disposal Group, Disposed of by Sale
Restructuring Cost and Reserve [Line Items]
Proceeds from sale of oil and gas properties, net of expenses				$ 527,000,000
Upward adjustment of purchase price				$ 16,000,000
RSA | Noteholders | Predecessor
Restructuring Cost and Reserve [Line Items]
Pro rata share of net cash proceeds						$ 100,000,000
Percentage of common stock issued in reorganization						95.00%
RSA | Noteholders | Senior Notes | Second Lien Notes | Predecessor
Restructuring Cost and Reserve [Line Items]
Aggregate principal amount of senior subordinated notes						$ 225,000,000
RSA | Predecessor Company's Common Stockholders
Restructuring Cost and Reserve [Line Items]
Percentage of common stock issued in reorganization			5.00%
Appalachia Regions of Pennsylvania and West Virginia | RSA | Predecessor
Restructuring Cost and Reserve [Line Items]
Minimum proceeds from sale of property							$ 350,000,000
Common Stock | RSA
Restructuring Cost and Reserve [Line Items]
New shares issued in reorganization (in shares) | shares	20,000
Common Stock | RSA | Noteholders | Predecessor
Restructuring Cost and Reserve [Line Items]
New shares issued in reorganization (in shares) | shares			19,000
Common Stock | RSA | Predecessor Company's Common Stockholders
Restructuring Cost and Reserve [Line Items]
New shares issued in reorganization (in shares) | shares	1,000
Warrants issued in reorganization (in shares) | shares	3,500
Exercise price of warrants or rights (in usd per share) | $ / shares	$ 42.04
Exercise period for warrants	4 years
Appalachia Properties | Disposal Group, Disposed of by Sale
Restructuring Cost and Reserve [Line Items]
Proceeds from sale of oil and gas properties, net of expenses			$ 512,500,000
Net consideration received for sale of Appalachia Properties			522,500,000
Appalachia Properties | Predecessor | Disposal Group, Disposed of by Sale
Restructuring Cost and Reserve [Line Items]
Net consideration received for sale of Appalachia Properties			$ 522,500,000