Equity Method Investments - Summary of Income Statement Data for Equity Method Investments (Details) - USD ($) $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Schedule of Equity Method Investments [Line Items]
Income from equity method investments	$ 109			$ 115			$ 330	$ 265
Total revenue	110			125			351	377
Costs and Expenses	75			76			230	215
Operating Income (Loss)	35			49			121	162
Net income	137	$ 144	$ 142	146	$ 119	$ 137	423	402
April 2020 Acquisition
Schedule of Equity Method Investments [Line Items]
Total revenue							62
Costs and Expenses							9
Operating Income (Loss)							53
Amberjack
Schedule of Equity Method Investments [Line Items]
Income from equity method investments	28			31			86	94
Amberjack | Equity Method Investment, Nonconsolidated Investee, Other
Schedule of Equity Method Investments [Line Items]
Total revenue	69			80			219	235
Costs and Expenses	16			18			52	54
Operating Income (Loss)	53			62			167	181
Net income	54			62			167	182
Mars
Schedule of Equity Method Investments [Line Items]
Income from equity method investments	33			35			92	93
Mars | Equity Method Investment, Nonconsolidated Investee, Other
Schedule of Equity Method Investments [Line Items]
Total revenue	68			82			201	212
Costs and Expenses	22			32			71	80
Operating Income (Loss)	46			50			130	132
Net income	46			50			130	133
Bengal
Schedule of Equity Method Investments [Line Items]
Income from equity method investments	5			8			14	18
Bengal | Equity Method Investment, Nonconsolidated Investee, Other
Schedule of Equity Method Investments [Line Items]
Total revenue	19			22			51	59
Costs and Expenses	9			7			24	23
Operating Income (Loss)	10			15			27	36
Net income	10			15			27	36
Explorer
Schedule of Equity Method Investments [Line Items]
Income from equity method investments	9			20			33	27
Explorer | Equity Method Investment, Nonconsolidated Investee, Other
Schedule of Equity Method Investments [Line Items]
Total revenue	75			122			251	159
Costs and Expenses	42			51			132	64
Operating Income (Loss)	33			71			119	95
Net income	25			55			91	73
Explorer | Equity Method Investment, Nonconsolidated Investee, Other | June 2019 Acquisition
Schedule of Equity Method Investments [Line Items]
Total revenue								344
Costs and Expenses								145
Operating Income (Loss)								199
Colonial Pipeline Company (“Colonial”)
Schedule of Equity Method Investments [Line Items]
Income from equity method investments	14			17			59	21
Colonial Pipeline Company (“Colonial”) | Equity Method Investment, Nonconsolidated Investee, Other
Schedule of Equity Method Investments [Line Items]
Total revenue	319			354			1,068	442
Costs and Expenses	172			190			501	234
Operating Income (Loss)	147			164			567	208
Net income	89			109			374	136
Colonial Pipeline Company (“Colonial”) | Equity Method Investment, Nonconsolidated Investee, Other | June 2019 Acquisition
Schedule of Equity Method Investments [Line Items]
Total revenue								1,050
Costs and Expenses								520
Operating Income (Loss)								530
Poseidon | Equity Method Investment, Nonconsolidated Investee, Other
Schedule of Equity Method Investments [Line Items]
Total revenue	36			31			99	96
Costs and Expenses	9			9			26	26
Operating Income (Loss)	27			22			73	70
Net income	26			20			68	63
Other
Schedule of Equity Method Investments [Line Items]
Income from equity method investments	5			4			16	12
Other | Equity Method Investment, Nonconsolidated Investee, Other
Schedule of Equity Method Investments [Line Items]
Total revenue	53			44			167	130
Costs and Expenses	30			21			91	76
Operating Income (Loss)	23			23			76	54
Net income	20			21			68	47
Mattox
Schedule of Equity Method Investments [Line Items]
Income from equity method investments	15			$ 0			30	$ 0
Mattox | Equity Method Investment, Nonconsolidated Investee, Other
Schedule of Equity Method Investments [Line Items]
Total revenue	22						44
Costs and Expenses	3						6
Operating Income (Loss)	19						38
Net income	$ 19						$ 38