Equity Method Investments - Schedule of Equity Investments in Affiliates (Details) - USD ($)	Dec. 31, 2020	Dec. 31, 2019	Jun. 30, 2019
Schedule of Equity Method Investments [Line Items]
Equity method investments	$ 1,013,000,000	$ 926,000,000
Mattox
Schedule of Equity Method Investments [Line Items]
Ownership interest (in percentage)	79.00%	0.00%
Equity method investments	$ 163,000,000	$ 0
Amberjack
Schedule of Equity Method Investments [Line Items]
Equity method investments	$ 382,000,000	$ 426,000,000
Amberjack Pipeline Company LLC - Series A
Schedule of Equity Method Investments [Line Items]
Ownership interest (in percentage)	75.00%	75.00%
Amberjack Pipeline Company LLC - Series B
Schedule of Equity Method Investments [Line Items]
Ownership interest (in percentage)	50.00%	50.00%
Mars
Schedule of Equity Method Investments [Line Items]
Ownership interest (in percentage)	71.50%	71.50%
Equity method investments	$ 152,000,000	$ 161,000,000
Bengal Pipeline Company LLC (“Bengal”)
Schedule of Equity Method Investments [Line Items]
Ownership interest (in percentage)	50.00%	50.00%
Equity method investments	$ 88,000,000	$ 88,000,000
Permian Basin
Schedule of Equity Method Investments [Line Items]
Ownership interest (in percentage)	50.00%	50.00%
Equity method investments	$ 83,000,000	$ 91,000,000
LOCAP
Schedule of Equity Method Investments [Line Items]
Ownership interest (in percentage)	41.48%	41.48%
Equity method investments	$ 12,000,000	$ 9,000,000
Explorer
Schedule of Equity Method Investments [Line Items]
Ownership interest (in percentage)	38.59%	38.59%
Equity method investments	$ 73,000,000	$ 88,000,000
Poseidon Oil Pipeline Company, L.L.C. (“Poseidon”)
Schedule of Equity Method Investments [Line Items]
Ownership interest (in percentage)	36.00%	36.00%
Equity method investments	$ 0	$ 0	$ 0
Colonial
Schedule of Equity Method Investments [Line Items]
Ownership interest (in percentage)	16.125%	16.125%
Equity method investments	$ 29,000,000	$ 30,000,000
Proteus
Schedule of Equity Method Investments [Line Items]
Ownership interest (in percentage)	10.00%	10.00%
Equity method investments	$ 14,000,000	$ 15,000,000
Endymion Oil Pipeline Company, LLC (“Endymion”)
Schedule of Equity Method Investments [Line Items]
Ownership interest (in percentage)	10.00%	10.00%
Equity method investments	$ 17,000,000	$ 18,000,000