SERIES A CUMULATIVE REDEEMABLE PREFERRED UNITS - Activity Related to Preferred Units (Details) - USD ($) $ in Thousands			12 Months Ended
		Feb. 14, 2020	Dec. 31, 2019	Jun. 12, 2019	Dec. 31, 2018
Increase (Decrease) in Temporary Equity [Roll Forward]
Redeemable noncontrolling interest - Preferred Units: beginning of period			$ 1,900,000
Redeemable noncontrolling interest - Preferred Units: end of period			701,000
Embedded derivative liability			102,929	$ 94,459	$ 0
Redeemable Noncontrolling Interest, Including Embedded Derivative Liability			658,528
Preferred Units, redemption price			$ 663,800
Preferred Units, redemption terms, internal rate of return			11.50%
Subsequent Event
Increase (Decrease) in Temporary Equity [Roll Forward]
Preferred Units, distribution in-kind		$ 11,200
Preferred Units, distribution, PIK units (in shares)		11,168
Preferred Unit limited partners
Movement In Preferred Units [Roll Forward]
Redeemable noncontrolling interest - Preferred Units: beginning of period (in shares)			0
Issuance of Preferred Units, net (in shares)			625,000
Distribution of in-kind additional Preferred Units (in shares)			13,163
Redeemable noncontrolling interest - Preferred Units: end of period (in shares)			638,163
Increase (Decrease) in Temporary Equity [Roll Forward]
Redeemable noncontrolling interest - Preferred Units: beginning of period			$ 0
Issuance of Preferred Units, net	[1]		516,790
Allocation of Altus Midstream net income			38,809
Redeemable noncontrolling interest - Preferred Units: end of period			$ 555,599
Preferred Units, redemption terms, internal rate of return			11.50%

[1] Certain redemption features embedded within the Preferred Unit purchase agreement require bifurcation and measurement at fair value. For further detail, refer to Note 12—Series A Cumulative Redeemable Preferred Units.