EQUITY METHOD INTERESTS - Rollforward Activity (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Movement In Equity Method Interests [Roll Forward]
Equity method interest, beginning balance	$ 121
Acquisitions	1,008	$ 0
Equity method interest, ending balance	1,095
Breviloba, LLC
Movement In Equity Method Interests [Roll Forward]
Equity method interest, beginning balance	0
Distributions	0
Equity income (loss), net	3
Accumulated other comprehensive loss	0
Equity method interest, ending balance	468
Altus Midstream Company
Movement In Equity Method Interests [Roll Forward]
Equity method interest, beginning balance	91
Acquisitions	670
Capital contributions	338
Distributions	(3)
Equity income (loss), net	1
Accumulated other comprehensive loss	(2)
Equity method interest, ending balance	1,095
Altus Midstream Company | Gulf Coast Express Pipeline LLC
Movement In Equity Method Interests [Roll Forward]
Equity method interest, beginning balance	91
Acquisitions	15
Capital contributions	169
Distributions	(3)
Equity income (loss), net	3
Accumulated other comprehensive loss	0
Equity method interest, ending balance	275
Altus Midstream Company | EPIC Crude Holdings, LP
Movement In Equity Method Interests [Roll Forward]
Equity method interest, beginning balance	0
Acquisitions	52
Capital contributions	83
Distributions	0
Equity income (loss), net	(5)
Accumulated other comprehensive loss	(2)
Equity method interest, ending balance	128
Altus Midstream Company | Permian Highway Pipeline LLC
Movement In Equity Method Interests [Roll Forward]
Equity method interest, beginning balance	0
Acquisitions	161
Capital contributions	63
Distributions	0
Equity income (loss), net	0
Accumulated other comprehensive loss	0
Equity method interest, ending balance	224
Altus Midstream Company | Breviloba, LLC
Movement In Equity Method Interests [Roll Forward]
Acquisitions	442
Capital contributions	23
Equity method interest, ending balance	$ 0