EQUITY METHOD INTERESTS - Rollforward Activity (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Movement In Equity Method Interests [Roll Forward]
Equity method interest, beginning balance	$ 121
Acquisitions	1,172	$ 91	$ 0
Equity method interest, ending balance	1,258	121
Shin Oak Pipeline (Breviloba, LLC)
Movement In Equity Method Interests [Roll Forward]
Equity method interest, beginning balance	0
Equity method interest, ending balance		0
ALTM
Movement In Equity Method Interests [Roll Forward]
Equity method interest, beginning balance	91
Acquisitions	671
Capital contributions	501
Distributions	(25)
Capitalized interest	2
Equity income (loss), net	19
Accumulated other comprehensive loss	(1)
Net of amortized basis difference	5
Equity method interest, ending balance	1,258	91
ALTM | Gulf Coast Express Pipeline LLC
Movement In Equity Method Interests [Roll Forward]
Equity method interest, beginning balance	91
Acquisitions	15
Capital contributions	184
Distributions	(16)
Capitalized interest	0
Equity income (loss), net	17
Accumulated other comprehensive loss	0
Equity method interest, ending balance	291	91
ALTM | EPIC Crude Holdings, LP
Movement In Equity Method Interests [Roll Forward]
Equity method interest, beginning balance	0
Acquisitions	52
Capital contributions	123
Distributions	0
Capitalized interest	0
Equity income (loss), net	(11)
Accumulated other comprehensive loss	(1)
Equity method interest, ending balance	163	0
ALTM | Permian Highway Pipeline LLC
Movement In Equity Method Interests [Roll Forward]
Equity method interest, beginning balance	0
Acquisitions	162
Capital contributions	147
Distributions	0
Capitalized interest	2
Equity income (loss), net	0
Accumulated other comprehensive loss	0
Equity method interest, ending balance	311	0
ALTM | Shin Oak Pipeline (Breviloba, LLC)
Movement In Equity Method Interests [Roll Forward]
Equity method interest, beginning balance	0
Acquisitions	442
Capital contributions	47
Distributions	(9)
Capitalized interest	0
Equity income (loss), net	13
Accumulated other comprehensive loss	0
Equity method interest, ending balance	493	$ 0
Revolving Credit Facility | ALTM
Movement In Equity Method Interests [Roll Forward]
Capitalized interest	$ 2