COMMITMENTS AND CONTINGENCIES - Agreements (Details) $ in Millions					1 Months Ended		12 Months Ended
	Nov. 12, 2019 bbl / d	Oct. 18, 2018 bbl / d	Aug. 01, 2018 bbl / d	Apr. 23, 2018 bbl / d	Dec. 31, 2019 bbl / d	Jul. 31, 2019 bbl / d	Dec. 31, 2019 USD ($)
Gray Oak Pipeline | Diamondback E&P LLC
Supply Commitment [Line Items]
Number of barrels per day				50,000
Deficiency Payments | $							$ 11
Full Service Term | Gray Oak Pipeline | Diamondback E&P LLC
Supply Commitment [Line Items]
Number of barrels per day	50,000
Trafigura Trading LLC
Supply Commitment [Line Items]
Number of barrels per day			25,000
Commitment, period			7 years
Plains Marketing LP
Supply Commitment [Line Items]
Number of barrels per day						50,000
Commitment, period						10 years
Plains Marketing LP | Maximum
Supply Commitment [Line Items]
Number of barrels per day						100,000
Shell Trading US Company
Supply Commitment [Line Items]
Commitment, period					3 years
Number of options to extend purchase agreement term					3		3
Purchase obligation extension period					1 year
Shell Trading US Company | Pre Commencement Terms | Minimum
Supply Commitment [Line Items]
Number of barrels per day					30,000
Shell Trading US Company | Pre Commencement Terms | Maximum
Supply Commitment [Line Items]
Number of barrels per day					40,000
Shell Trading US Company | Full Service Term | Maximum
Supply Commitment [Line Items]
Number of barrels per day					50,000
Vitol Inc
Supply Commitment [Line Items]
Number of barrels per day		23,750
Vitol Inc | Epic Pipeline
Supply Commitment [Line Items]
Commitment, period		7 years
Additional number of barrels per day		50,000
Vitol Inc | Full Service Term | Gray Oak Pipeline
Supply Commitment [Line Items]
Number of barrels per day		50,000
Commitment, period		7 years
Additional number of barrels per day		50,000