LONG TERM DEBT - 6.75% Senior Notes (Details) - USD ($) $ in Thousands							3 Months Ended	9 Months Ended	12 Months Ended
	Aug. 07, 2019	Feb. 15, 2018	Oct. 10, 2017	Sep. 07, 2017	Jul. 25, 2017	Feb. 16, 2017	Mar. 31, 2017	Oct. 01, 2019	Dec. 31, 2018		Dec. 31, 2017	Dec. 31, 2019	Oct. 08, 2019	Aug. 02, 2019	Oct. 08, 2018	Oct. 07, 2017	Jul. 10, 2017
Current and long-term debt
Accrued and unpaid interest			$ 4,100
Gains (Losses) on Extinguishment of Debt											$ (114,931)
Unamortized debt issuance costs									$ 11,100			$ 0
Write-off debt discounts/premium and debt issuance costs								$ 10,953
Interest expense not accrued	$ 7,100
12.0% senior secured second lien notes due 2022
Current and long-term debt
Interest rate (as a percent)																12.00%
Gains (Losses) on Extinguishment of Debt											(29,200)
Loss on the write-off of the discount on notes											6,200
6.75% senior notes due 2025
Current and long-term debt
Principal amount				$ 850,000		$ 850,000			625,005	[1]							$ 850,000
Interest rate (as a percent)						6.75%						6.75%	6.75%	6.75%	6.75%		6.75%
Net proceeds from issuance						$ 834,100
Redemption price of debt instrument (as a percent)			103.00%
Gains (Losses) on Extinguishment of Debt											(28,900)
Loss on the repurchase for the tender premium paid											12,800
Loss on the write-off of the discount on notes											8,300
Loss on write off of debt issuance costs									7,800		$ 7,800
Percentage of holders concluded a consent solicitation					99.00%
Percentage of consent fee paid					2.00%
Consent fee paid					$ 16,900
Principal amount repurchased			$ 425,000
Write-off debt discounts/premium and debt issuance costs	6,600
Additional 2025 Notes
Current and long-term debt
Principal amount		$ 200,000
Net proceeds from issuance		$ 202,400
Issue price as a percentage of par value		103.00%
Unamortized premium related to debt issued									5,400
Unamortized debt issuance costs									$ 10,100
Write-off of debt premium	$ 4,900
8.625% senior secured second lien notes due 2020
Current and long-term debt
Interest rate (as a percent)						8.625%
Gains (Losses) on Extinguishment of Debt							$ (56,900)
Loss on the repurchase for the tender premium paid							30,900
Loss on the write-off of the discount on notes							$ 26,000
Williston Basin Assets | 6.75% senior notes due 2025
Current and long-term debt
Redemption price of debt instrument (as a percent)				103.00%
Principal amount repurchased				$ 425,000

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