Equity Method Investments - Summary of Equity Method Investment Financial Information (Details) - USD ($) $ in Millions		3 Months Ended			9 Months Ended
		Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Sep. 30, 2020		Sep. 30, 2019		Dec. 31, 2019
Schedule of Equity Method Investments [Line Items]
Revenues		$ 2,247		$ 2,280	$ 5,320		$ 6,725
Equity method investments		4,081			4,081				$ 5,275
Costs and Expenses		1,348		1,354	6,029		4,002
Net (loss)/income		674		689	(1,387)		2,035
Income/(loss) from equity method investments(1)		83		95	(1,012)	[1],[2]	255
Assets, Current		1,272			1,272				1,484
Liabilities, Current		$ 1,531			1,531				2,132
Equity Method Investment, Other than Temporary Impairment			$ 1,264		$ 1,264
MarEn Bakken Company LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		25.00%			25.00%
Illinois Extension
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		35.00%			35.00%
LOOP
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		41.00%			41.00%
Whistler Pipeline LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		38.00%			38.00%
W2W Holdings LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		50.00%			50.00%
Wink to Webster Pipeline LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		15.00%			15.00%
Explorer
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		25.00%			25.00%
MarkWest Utica EMG
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		57.00%			57.00%
Equity Method Investment, Other than Temporary Impairment			$ 1,251
Sherwood Midstream
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		50.00%			50.00%
MarkWest EMG Jefferson Dry Gas Gathering Company, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		67.00%			67.00%
Centrahoma Processing LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		40.00%			40.00%
Indirect Ownership Interest [Member] | Bakken Pipeline System [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		9.19%			9.19%
Indirect Ownership Interest [Member] | Sherwood Midstream Holdings
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		24.51%			24.51%
Direct Ownership Interest [Member] | Andeavor Logistics Rio Pipeline [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		67.00%			67.00%
Direct Ownership Interest [Member] | Minnesota Pipe Line Company, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		17.00%			17.00%
Direct Ownership Interest [Member] | Rendezvous Gas Services, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		78.00%			78.00%
Direct Ownership Interest [Member] | Sherwood Midstream Holdings
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage		51.00%			51.00%
G&P
Schedule of Equity Method Investments [Line Items]
Difference between carrying amount and underlying equity		$ (58)			$ (58)				1,000
Difference between carrying amount and underlying equity portion related to goodwill		31			31				498
G&P | MarkWest Utica EMG
Schedule of Equity Method Investments [Line Items]
Equity method investments	[3]	720			720				1,984
G&P | Sherwood Midstream
Schedule of Equity Method Investments [Line Items]
Equity method investments	[3]	560			560				537
G&P | MarkWest EMG Jefferson Dry Gas Gathering Company, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[3]	307			307				302
G&P | Rendezvous Gas Services, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[3]	164			164				170
G&P | Sherwood Midstream Holdings
Schedule of Equity Method Investments [Line Items]
Equity method investments	[3]	151			151				157
G&P | Centrahoma Processing LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments		147			147				153
G&P | Other VIEs and Non-VIEs [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[3]	230			230				198
L&S
Schedule of Equity Method Investments [Line Items]
Difference between carrying amount and underlying equity		331			331				329
Difference between carrying amount and underlying equity portion related to goodwill		167			167				167
L&S | MarEn Bakken Company LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[4]	469			469				481
L&S | Illinois Extension
Schedule of Equity Method Investments [Line Items]
Equity method investments		261			261				265
L&S | LOOP
Schedule of Equity Method Investments [Line Items]
Equity method investments		249			249				238
L&S | Andeavor Logistics Rio Pipeline [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[3]	195			195				202
L&S | Minnesota Pipe Line Company, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments		189			189				190
L&S | Whistler Pipeline LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[3]	184			184				134
L&S | W2W Holdings LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[3],[5]	77			77				0
L&S | Wink to Webster Pipeline LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[3],[5]	0			0				126
L&S | Explorer
Schedule of Equity Method Investments [Line Items]
Equity method investments		78			78				83
L&S | Other VIEs and Non-VIEs [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[3]	100			100				55
Operating Segments | G&P
Schedule of Equity Method Investments [Line Items]
Revenues	[6]	913		901	1,330		2,742
Equity method investments		2,279			2,279				3,501
Income/(loss) from equity method investments(1)		47		35	(1,138)		96
Operating Segments | L&S
Schedule of Equity Method Investments [Line Items]
Revenues	[6]	1,334		1,379	3,990		3,983
Equity method investments		1,802			1,802				1,774
Income/(loss) from equity method investments(1)		36		$ 60	126		159
Other VIEs and Non-VIEs [Member]
Schedule of Equity Method Investments [Line Items]
Revenues					1,065		1,595
Costs and Expenses					713		685
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest					352		910
Net (loss)/income					247		797
Income/(loss) from equity method investments(1)					(1,012)	[7]	255	[8]
Assets, Current		1,141			1,141				864
Assets, Noncurrent		11,422			11,422				10,996
Liabilities, Current		498			498				437
Liabilities, Noncurrent		2,468			2,468				1,127
Non-VIEs [Member]
Schedule of Equity Method Investments [Line Items]
Revenues					933		1,116
Costs and Expenses					405		434
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest					528		682
Net (loss)/income					477		605
Income/(loss) from equity method investments(1)					126	[7]	166	[8]
Assets, Current		367			367				330
Assets, Noncurrent		5,024			5,024				5,134
Liabilities, Current		194			194				245
Liabilities, Noncurrent		857			857				822
Other VIEs [Member]
Schedule of Equity Method Investments [Line Items]
Revenues					132		479
Costs and Expenses					308		251
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest					(176)		228
Net (loss)/income					(230)		192
Income/(loss) from equity method investments(1)					(1,138)	[7]	$ 89	[8]
Assets, Current		774			774				534
Assets, Noncurrent		6,398			6,398				5,862
Liabilities, Current		304			304				192
Liabilities, Noncurrent		$ 1,611			$ 1,611				$ 305

[1] The 2020 period includes $1,264 million of impairment expense. See Note 4.

[2] The nine months ended September 30, 2020 includes $1,264 million of impairment expense. See Note 4.

[3] Investments deemed to be VIEs. Some investments included within “Other” have also been deemed to be VIEs.

[4] The investment in MarEn Bakken Company LLC includes our 9.19 percent indirect interest in a joint venture (“Dakota Access”) that owns and operates the Dakota Access Pipeline and Energy Transfer Crude Oil Pipeline projects, collectively referred to as the Bakken Pipeline system or DAPL.

[5] During the nine months ended September 30, 2020, we contributed our ownership in Wink to Webster Pipeline LLC to W2W Holdings LLC.

[6] Within the total segment revenues and other income amounts presented above, third party revenues for the L&S segment were $139 million and $443 million for the three and nine months ended September 30, 2020, respectively, and $182 million and $498 million for the three and nine months ended September 30, 2019, respectively. Third party revenues for the G&P segment were $858 million and $1,181 million for the three and nine months ended September 30, 2020, respectively, and $843 million and $2,581 million for the three and nine months ended September 30, 2019, respectively.

[7] Includes the impact of any basis differential amortization or accretion in addition to the impairment of $1,264 million.

[8] Includes the impact of any basis differential amortization or accretion.