ACQUISITIONS AND DIVESTITURES - Divestitures (Details) $ in Thousands						3 Months Ended	9 Months Ended	12 Months Ended
	Nov. 09, 2017 USD ($)	Sep. 19, 2017 USD ($)	Jul. 10, 2017 USD ($) subsidiary	Jan. 24, 2017 USD ($)	Jan. 01, 2017 USD ($)	Dec. 31, 2019 USD ($)	Oct. 01, 2019 USD ($)	Dec. 31, 2018 USD ($)		Dec. 31, 2017 USD ($)	Oct. 08, 2019	Aug. 02, 2019	Oct. 08, 2018	Oct. 07, 2017	Sep. 07, 2017 USD ($)	Feb. 16, 2017 USD ($)
Divestitures
Increase (Decrease) In Gains On Disposition Of Water Assets						$ 500	$ 3,600
Proceeds received from sales of oil and natural gas assets							$ 1,247	$ 3,816		$ 2,003,894
Gain (loss) on extinguishment of debt										(114,931)
Proceeds received from sale of other operating property and equipment						$ 6		216,083		21,798
Gain (loss) from sale of other operating property and equipment								(7,235)		721,573
12.0% senior secured second lien notes due 2022
Divestitures
Interest rate (as a percent)														12.00%
Gain (loss) on extinguishment of debt										(29,200)
Loss on the repurchase for the make whole premium										23,000
Loss on the write-off of the discount on notes										6,200
6.75% senior notes due 2025
Divestitures
Repurchase amount of outstanding principal			$ 425,000
Aggregate principal amount drawn			$ 850,000					625,005	[1]						$ 850,000	$ 850,000
Interest rate (as a percent)			6.75%			6.75%					6.75%	6.75%	6.75%			6.75%
Gain (loss) on extinguishment of debt										(28,900)
Loss on the write-off of the discount on notes										8,300
Gain on sale of oil and natural gas assets
Divestitures
Gain (loss) from sale of other operating property and equipment			$ 0	$ 0
Williston Basin Assets
Divestitures
Gain (loss) from sale of other operating property and equipment			0					$ (7,200)		485,900
Williston Basin Assets | Property Plant And Equipment, Other
Divestitures
Proceeds received from sales of oil and natural gas assets			1,390,000
Proceeds received from sale of other operating property and equipment			$ 10,900
Williston Basin Assets | Disposal Group Disposed of by Sale
Divestitures
Ownership percentage disposed			100.00%
Number of subsidiaries | subsidiary			2
Proceeds received from sales of oil and natural gas assets			$ 1,400,000
El Halcon Assets
Divestitures
Gain (loss) from sale of other operating property and equipment				0						235,700
El Halcon Assets | Property Plant And Equipment, Other
Divestitures
Proceeds received from sales of oil and natural gas assets				484,100
Proceeds received from sale of other operating property and equipment					$ 10,200
El Halcon Assets | Gain on sale of oil and natural gas assets
Divestitures
Gain (loss) from sale of other operating property and equipment										$ 235,700
El Halcon Assets | Disposal Group Disposed of by Sale
Divestitures
Proceeds from sales of interests				$ 491,100
Non-operating owner | Williston Basin Assets
Divestitures
Proceeds from sales of interests		$ 103,400
Gain (loss) on sale	$ 0

[1] The 6.75% senior notes were cancelled on October 8, 2019 upon emergence from chapter 11 bankruptcy.