SERIES A CUMULATIVE REDEEMABLE PREFERRED UNITS - Activity Related to Preferred Units (Details) shares in Thousands, $ in Thousands		3 Months Ended				9 Months Ended				12 Months Ended
		Sep. 30, 2021 USD ($) shares		Sep. 30, 2020 USD ($)	[2]	Sep. 30, 2021 USD ($) shares		Sep. 30, 2020 USD ($) shares		Dec. 31, 2020 USD ($) shares
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance	[1]					$ 608,381
Accreted redemption value adjustment						13,187
Ending balance		$ 634,795				634,795				$ 608,381	[1]
Embedded derivative liability		120,522				120,522				$ 139,009	[1]
Redeemable noncontrolling interest, including embedded derivative liability		$ 755,317				$ 755,317
Preferred Units, redemption terms, internal rate of return		11.50%				11.50%
Preferred Units, redemption terms, multiple of invested capital		1.3				1.3
Preferred Units, invested capital		$ 812,500				$ 812,500
Preferred Units, redemption price		$ 729,800				$ 729,800
Preferred Unit limited partners
Movement In Preferred Units [Roll Forward]
Redeemable noncontrolling interest - Preferred Units: beginning of period (in shares) | shares						660,694		638,163		638,163
Distribution of in-kind additional Preferred Units (in shares) | shares										22,531
Redeemable noncontrolling interest - Preferred Units: end of period (in shares) | shares		660,694				660,694				660,694
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance						$ 608,381		$ 555,599		$ 555,599
Cash distributions paid to Preferred Unit limited partners				$ (11,562)		(34,686)	[3]	$ (11,562)	[2]	(23,124)
Distributions payable to Preferred Unit limited partners		$ (11,562)	[2]			(11,562)	[3]
Allocation of Altus Midstream net income						59,475				75,906
Ending balance		$ 634,795				$ 634,795				$ 608,381

[1] The Consolidated Balance Sheet as of December 31, 2020 has been derived from the audited consolidated financial statements, revised to reflect the Company’s fair value change of its underlying warrants. Refer to Note 1—Summary of Significant Accounting Policies, see the section titled Revision of Previously Issued Consolidated Financial Statements for Immaterial Adjustment for further information.

[2] Certain redemption features embedded within the Preferred Units require bifurcation and measurement at fair value. For further detail, refer to Note 10—Series A Cumulative Redeemable Preferred Units.

[3] Certain redemption features embedded within the Preferred Units require bifurcation and measurement at fair value. For further detail, refer to Note 10—Series A Cumulative Redeemable Preferred Units.