Equity Method Investments - Summary of Equity Method Investment Financial Information (Details) - USD ($) $ in Millions		3 Months Ended					6 Months Ended
		Jun. 30, 2020		Mar. 31, 2020	Jun. 30, 2019		Jun. 30, 2020		Jun. 30, 2019		Dec. 31, 2019
Schedule of Equity Method Investments [Line Items]
Revenues		$ 2,081			$ 2,210	[1],[2]	$ 3,073		$ 4,445	[1],[2]
Equity method investments		4,065					4,065				$ 5,275
Costs and Expenses		1,203			1,325	[1]	4,681		2,648	[1]
Net (loss)/income		655			657	[1],[3],[4]	(2,061)		1,346	[1],[3],[5]
Income/(loss) from equity method investments(2)		89			83	[1],[4]	(1,095)	[6],[7]	160	[1],[5]
Assets, Current		1,386					1,386				1,484
Liabilities, Current		$ 1,228					1,228				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		24.47%					24.47%
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		$ (59)					$ (59)				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	[8]	725					725				1,984
G&P | Sherwood Midstream
Schedule of Equity Method Investments [Line Items]
Equity method investments	[8]	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	[8]	308					308				302
G&P | Rendezvous Gas Services, L.L.C. [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[8]	166					166				170
G&P | Sherwood Midstream Holdings
Schedule of Equity Method Investments [Line Items]
Equity method investments	[8]	152					152				157
G&P | Centrahoma Processing LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments		151					151				153
G&P | Other VIEs and Non-VIEs [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[8]	226					226				198
L&S
Schedule of Equity Method Investments [Line Items]
Difference between carrying amount and underlying equity		330					330				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	[9]	477					477				481
L&S | Illinois Extension
Schedule of Equity Method Investments [Line Items]
Equity method investments		268					268				265
L&S | LOOP
Schedule of Equity Method Investments [Line Items]
Equity method investments		242					242				238
L&S | Andeavor Logistics Rio Pipeline [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[8]	196					196				202
L&S | Minnesota Pipe Line Company, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments		190					190				190
L&S | Whistler Pipeline LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[8]	188					188				134
L&S | W2W Holdings LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments		77					77				0	[8],[10]
L&S | Wink to Webster Pipeline LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[8],[10]	0					0				126
L&S | Explorer
Schedule of Equity Method Investments [Line Items]
Equity method investments		79					79				83
L&S | Other VIEs and Non-VIEs [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments	[8]	60					60				55
Operating Segments | G&P
Schedule of Equity Method Investments [Line Items]
Revenues		791	[11]		902	[4],[11]	417		1,841
Equity method investments		2,288					2,288				3,501
Income/(loss) from equity method investments(2)		49			29	[4]	(1,185)		61
Operating Segments | L&S
Schedule of Equity Method Investments [Line Items]
Revenues		1,290	[11]		1,308	[4],[11]	2,656		2,604
Equity method investments		1,777					1,777				1,774
Income/(loss) from equity method investments(2)		40			$ 54	[4]	90		99
Other VIEs and Non-VIEs [Member]
Schedule of Equity Method Investments [Line Items]
Revenues							597		1,030
Costs and Expenses							476		454
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest							121		576
Net (loss)/income							49		510
Income/(loss) from equity method investments(2)							(1,095)	[12]	160	[13]
Assets, Current		674					674				864
Assets, Noncurrent		10,885					10,885				10,996
Liabilities, Current		446					446				437
Liabilities, Noncurrent		1,509					1,509				1,127
Non-VIEs [Member]
Schedule of Equity Method Investments [Line Items]
Revenues							640		724	[14]
Costs and Expenses							274		295	[14]
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest							366		429	[14]
Net (loss)/income							332		383	[14]
Income/(loss) from equity method investments(2)							83	[12]	106	[13],[14]
Assets, Current		317					317				330
Assets, Noncurrent		5,061					5,061				5,134
Liabilities, Current		181					181				245
Liabilities, Noncurrent		853					853				822
Other VIEs [Member]
Schedule of Equity Method Investments [Line Items]
Revenues							(43)		306	[14]
Costs and Expenses							202		159	[14]
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest							(245)		147	[14]
Net (loss)/income							(283)		127	[14]
Income/(loss) from equity method investments(2)							(1,178)	[12]	$ 54	[13],[14]
Assets, Current		357					357				534
Assets, Noncurrent		5,824					5,824				5,862
Liabilities, Current		265					265				192
Liabilities, Noncurrent		$ 656					$ 656				$ 305

[1] Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[2] Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[3] Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[4] Financial information for the three and six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

[5] Financial information for the six months ended June 30, 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.

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

[7] The six months ended June 30, 2020 includes $1,264 million of impairment expense. See Note 4.

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

[9] 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.

[10] During the six months ended June 30, 2020, we contributed our ownership in Wink to Webster Pipeline LLC to W2W Holdings LLC.

[11] Within the total segment revenues and other income amounts presented above, third party revenues for the L&S segment were $146 million and $304 million for the three and six months ended June 30, 2020, respectively, and $163 million and $316 million for the three and six months ended June 30, 2019, respectively. Third party revenues for the G&P segment were $748 million and $323 million for the three and six months ended June 30, 2020, respectively, and $851 million and $1,738 million for the three and six months ended June 30, 2019, respectively.

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

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

[14] Financial information for the first six months of 2019 has been retrospectively adjusted for the acquisition of ANDX. See Notes 1 and 3.