The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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-Publisher FASB
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-SubTopic 10
-Section 50
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Percentage investment held by members or limited partners of limited liability company (LLC) or limited partnership (LP).

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 272
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (b)
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- Definition

Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 1
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-SubTopic 10
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-Paragraph 1
-Subparagraph (SX 210.5-02.13)
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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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The number of units or percentage investment held in the subsidiary by the limited liability company or limited partnership.

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Percentage of the Variable Interest Entity's (VIE) voting interest owned by (or beneficial interest in) the reporting entity (directly or indirectly).

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-Publisher FASB
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-SubTopic 10
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General, Description of Business, and Basis of Presentation (Details) - USD ($) $ in Millions	1 Months Ended	9 Months Ended
	Jun. 30, 2019	Sep. 30, 2020	Dec. 31, 2019	Apr. 30, 2019
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Property, plant, and equipment		$ 42,384	$ 41,510
Northeast JV [Member]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Subsidiary of Limited Liability Company or Limited Partnership, Ownership Interest	65.00%
Transmission And Gulf Of Mexico [Member] \| Williams Companies Inc [Member] \| Gulfstar One [Member]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Variable Interest Entity Ownership Percentage		51.00%
Northeast G And P [Member] \| Williams Companies Inc [Member] \| Northeast JV [Member]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Variable Interest Entity Ownership Percentage		65.00%
Northeast G And P [Member] \| Williams Companies Inc [Member] \| Cardinal Gas Services LLC [Member]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Variable Interest Entity Ownership Percentage		66.00%
Northeast G And P [Member] \| Williams Companies Inc [Member] \| Appalachia Midstream Services, LLC [Member]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Subsidiary of Limited Liability Company or Limited Partnership, Ownership Interest		66.00%
West [Member] \| Brazos Permian II LLC [Member]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Limited Liability Company or Limited Partnership, Members or Limited Partners, Ownership Interest		15.00%
West [Member] \| Williams Companies Inc [Member] \| Conway Fractionator [Member]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Subsidiary of Limited Liability Company or Limited Partnership, Ownership Interest		50.00%
Northeast Supply Enhancement Project [Member]
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]
Property, plant, and equipment		$ 215
Gulfstream Natural Gas System, LLC [Member] \| Transmission And Gulf Of Mexico [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage		50.00%
Discovery Producer Services LLC [Member] \| Transmission And Gulf Of Mexico [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage		60.00%
Laurel Mountain Midstream, LLC [Member] \| Northeast G And P [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage		69.00%
Caiman Energy II [Member] \| Northeast G And P [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage		58.00%
Overland Pass Pipeline Company LLC [Member] \| West [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage		50.00%
Rocky Mountain Midstream Holdings LLC [Member] \| West [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage		50.00%
Jackalope Gas Gathering Services LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage				50.00%
Jackalope Gas Gathering Services LLC [Member] \| West [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage				50.00%