Enable Midstream Partners (ENBL) 10-Q 4 Aug 21 2021 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2021	Jul. 16, 2021
Entity Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2021
Document Transition Report	false
Entity File Number	1-36413
Entity Registrant Name	ENABLE MIDSTREAM PARTNERS, LP
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	72-1252419
Entity Address, Address Line One	499 West Sheridan Avenue,
Entity Address, Address Line Two	Suite 1500
Entity Address, City or Town	Oklahoma City,
Entity Address, State or Province	OK
Entity Address, Postal Zip Code	73102
City Area Code	405
Local Phone Number	525-7788
Title of 12(b) Security	Common Units Representing Limited Partner Interests
Trading Symbol	ENBL
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Shell Company	false
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Amendment Flag	false
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q2
Entity Central Index Key	0001591763
Entity Common Stock, Shares Outstanding		435,877,546
Current Fiscal Year End Date	--12-31

Condensed Consolidated Statemen

Condensed Consolidated Statements of Income (Unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Revenues (including revenues from affiliates (Note 13)):
Total Revenues	$ 787	$ 515	$ 1,757	$ 1,163
Cost and Expenses (including expenses from affiliates (Note 13)):
Cost of natural gas and natural gas liquids (excluding depreciation and amortization shown separately)	426	177	945	403
Operation and maintenance	91	115	175	217
General and administrative	25	21	62	45
Depreciation and amortization	103	105	209	209
Impairments of property, plant and equipment and goodwill (Note 7)	0	0	0	28
Taxes other than income tax	18	17	36	35
Total Cost and Expenses	663	435	1,427	937
Operating Income	124	80	330	226
Other Income (Expense):
Interest expense	(42)	(46)	(84)	(93)
Equity in earnings (losses) of equity method affiliate, net	0	5	1	11
Other, net	6	5	6	5
Total Other Expense	(36)	(36)	(77)	(77)
Income Before Income Tax
Income Before Income Tax	88	44	253	149
Income tax benefit	0	0	0	0
Net Income
Net Income	88	44	253	149
Less: Net income (loss) attributable to noncontrolling interest
Less: Net income (loss) attributable to noncontrolling interest	1	0	2	(7)
Net Income Attributable to Limited Partners
Net Income Attributable to Limited Partners	87	44	251	156
Less: Series A Preferred Unit distributions (Note 6)
Less: Series A Preferred Unit distributions (Note 6)	8	9	17	18
Net Income Attributable to Common Units (Note 5)
Net Income Attributable to Common Units (Note 5)	79	35	234	138
Common Unit [Member]
Net Income Attributable to Common Units (Note 5)
Net Income Attributable to Common Units (Note 5)	$ 79	$ 35	$ 234	$ 138
Basic and Diluted earnings per unit and weighted average number of units outstanding
Basic and diluted earnings per unit (Note 5)	$ 0.18	$ 0.08	$ 0.53	$ 0.32
Diluted	$ 0.18	$ 0.08	$ 0.52	$ 0.30
Product
Revenues (including revenues from affiliates (Note 13)):
Total Revenues	$ 460	$ 196	$ 1,087	$ 484
Natural Gas, Gathering, Transportation, Marketing and Processing
Revenues (including revenues from affiliates (Note 13)):
Total Revenues	$ 327	$ 319	$ 670	$ 679

Condensed Consolidated Statem_2

Condensed Consolidated Statement of Comprehensive Income Statement (Unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Statement of Comprehensive Income [Abstract]
Net income	$ 88	$ 44	$ 253	$ 149
Other comprehensive income (loss):
Change in fair value of interest rate derivative instruments	0	0	0	(6)
Reclassification of interest rate derivative losses to net income	2	0	3	0
Other comprehensive income (loss)	2	0	3	(6)
Comprehensive income	90	44	256	143
Less: Comprehensive income (loss) attributable to noncontrolling interest	1	0	2	(7)
Comprehensive income attributable to Limited Partners	$ 89	$ 44	$ 254	$ 150

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Current Assets:
Cash and cash equivalents	$ 28	$ 3
Accounts receivable, net of allowance for doubtful accounts (Note 1)	326	248
Accounts receivable—affiliated companies	12	15
Inventory	43	42
Gas imbalances	28	42
Other current assets, net of allowance for doubtful accounts (Note 1)	38	31
Total current assets	475	381
Property, Plant and Equipment:
Property, plant and equipment	13,354	13,220
Less: Accumulated depreciation and amortization	2,715	2,555
Property, plant and equipment, net	10,639	10,665
Other Assets:
Intangible assets, net	508	539
Investment in equity method affiliate	73	76
Other	64	68
Total other assets	645	683
Total Assets	11,759	11,729
Current Liabilities:
Accounts payable	161	149
Accounts payable—affiliated companies	2	2
Current portion of long-term debt	800	0
Short-term debt	171	250
Taxes accrued	46	34
Gas imbalances	14	19
Other	123	128
Total current liabilities	1,317	582
Other Liabilities:
Accumulated deferred income taxes, net	4	5
Regulatory liabilities	26	25
Other	66	71
Total other liabilities	96	101
Long-Term Debt	3,153	3,951
Commitments and Contingencies (Note 14)
Partners’ Equity:
Series A Preferred Units (14,520,000 issued and outstanding at June 30, 2021 and December 31, 2020)	362	362
Common Units (435,866,139 issued and outstanding at June 30, 2021 and 435,549,892 issued and outstanding at December 31, 2020)	6,809	6,713
Accumulated other comprehensive loss	(3)	(6)
Noncontrolling interest	25	26
Total Partners’ Equity	7,193	7,095
Total Liabilities and Partners’ Equity	$ 11,759	$ 11,729

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - shares	Jun. 30, 2021	Dec. 31, 2020
Common Unit [Member]
Common units issued	435,866,139	435,549,892
Common units outstanding	435,866,139	435,549,892
Series A Preferred Units [Member]
Preferred Units, Issued	14,520,000	14,520,000
Preferred Units, Outstanding	14,520,000	14,520,000

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Cash Flows from Operating Activities:
Net income	$ 253	$ 149
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	209	209
Deferred income taxes	0	1
Impairments of property, plant and equipment and goodwill	0	28
Net loss on sale/retirement of assets	0	17
Equity in earnings of equity method affiliate	(1)	(11)
Return on investment in equity method affiliate	1	11
Equity-based compensation	8	7
Amortization of debt costs and discount	3	1
Other, net	(6)	(5)
Changes in other assets and liabilities:
Accounts receivable, net	(78)	20
Accounts receivable—affiliated companies	3	10
Inventory	(1)	3
Gas imbalance assets	14	(3)
Other current assets, net	(9)	(10)
Other assets	3	3
Accounts payable	14	(71)
Accounts payable—affiliated companies	0	1
Gas imbalance liabilities	(5)	0
Other current liabilities	6	(45)
Other liabilities	(1)	(4)
Net cash provided by operating activities	413	311
Cash Flows from Investing Activities:
Capital expenditures (excluding equity AFUDC)	(151)	(102)
Proceeds from sale of assets	3	19
Return of investment in equity method affiliate	3	8
Other, net	2	2
Net cash used in investing activities	(143)	(73)
Cash Flows from Financing Activities:
Decrease in short-term debt	(79)	(125)
Repayment of long-term debt	0	(267)
Proceeds from Revolving Credit Facility	0	869
Repayment of Revolving Credit Facility	0	(469)
Distributions to common unitholders	(144)	(216)
Distributions to preferred unitholders	(17)	(18)
Distributions to non-controlling interests	(3)	(3)
Cash paid for employee equity-based compensation	(2)	(2)
Net cash used in financing activities	(245)	(231)
Net Increase in Cash, Cash Equivalents and Restricted Cash	25	7
Cash, Cash Equivalents and Restricted Cash at Beginning of Period	3	4
Cash, Cash Equivalents and Restricted Cash at End of Period	$ 28	$ 11

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Partners' Equity (Unaudited) - USD ($) shares in Millions, $ in Millions	Total	Cumulative Effect, Period of Adoption, Adjustment	Noncontrolling Interest [Member]	Series A Preferred Units [Member]Preferred Units	Common Unit [Member]Partners' Capital	Common Unit [Member]Partners' CapitalCumulative Effect, Period of Adoption, Adjustment	AOCI Attributable to Parent
Balance, beginning of period at Dec. 31, 2019	$ 7,409	$ (3)	$ 37	$ 362	$ 7,013	$ (3)	$ (3)
Balance, beginning of period, units at Dec. 31, 2019				15	435
Changes in Partners' Capital
Net Income	105		(7)	$ 9	$ 103
Other comprehensive loss	(6)						(6)
Partners' Capital Account, Distributions	(156)		(3)	(9)	(144)
Partners' Capital Account, Unit-based Compensation, Net of Taxes	3				$ 3
Equity-based compensation, net of units for employee taxes, units					0
Balance, end of period at Mar. 31, 2020	7,352		27	$ 362	$ 6,972		(9)
Balance, end of period, units at Mar. 31, 2020				15	435
Changes in Partners' Capital
Net Income	44		0	$ 9	$ 35
Partners' Capital Account, Distributions	(81)		0	(9)	(72)
Partners' Capital Account, Unit-based Compensation, Net of Taxes	2				$ 2
Equity-based compensation, net of units for employee taxes, units					0
Balance, end of period at Jun. 30, 2020	7,317		27	$ 362	$ 6,937		(9)
Balance, end of period, units at Jun. 30, 2020				15	435
Balance, beginning of period at Dec. 31, 2020	7,095		26	$ 362	$ 6,713		(6)
Balance, beginning of period, units at Dec. 31, 2020				15	435
Changes in Partners' Capital
Net Income	165		1	$ 9	$ 155
Other comprehensive loss	1						1
Partners' Capital Account, Distributions	(82)		(1)	(9)	(72)
Partners' Capital Account, Unit-based Compensation, Net of Taxes	2				$ 2
Equity-based compensation, net of units for employee taxes, units					1
Balance, end of period at Mar. 31, 2021	7,181		26	$ 362	$ 6,798		(5)
Balance, end of period, units at Mar. 31, 2021				15	436
Changes in Partners' Capital
Net Income	88		1	$ 8	$ 79
Other comprehensive loss	2						2
Partners' Capital Account, Distributions	(82)		(2)	(8)	(72)
Partners' Capital Account, Unit-based Compensation, Net of Taxes	4				$ 4
Equity-based compensation, net of units for employee taxes, units					0
Balance, end of period at Jun. 30, 2021	$ 7,193		$ 25	$ 362	$ 6,809	$ 0	$ (3)
Balance, end of period, units at Jun. 30, 2021				15	436

Summary of Significant Accounti

Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Organization Enable Midstream Partners, LP (the Partnership) is a Delaware limited partnership whose assets and operations are organized into two reportable segments: (i) gathering and processing and (ii) transportation and storage. Our gathering and processing segment primarily provides natural gas gathering and processing services to our producer customers and crude oil, condensate and produced water gathering services to our producer and refiner customers. The transportation and storage segment provides interstate and intrastate natural gas pipeline transportation and storage services primarily to our producer, power plant, LDC and industrial end-user customers. Our natural gas gathering and processing assets are primarily located in Oklahoma, Texas, Arkansas and Louisiana and serve natural gas production in the Anadarko, Arkoma and Ark-La-Tex Basins. Crude oil gathering assets are located in Oklahoma and serve crude oil production in the SCOOP and STACK plays of the Anadarko Basin and in North Dakota and serve crude oil production in the Bakken Shale formation of the Williston Basin. The Partnership’s natural gas transportation and storage assets consist primarily of an interstate pipeline system extending from western Oklahoma and the Texas Panhandle to Louisiana, an interstate pipeline system extending from Louisiana to Illinois, an intrastate pipeline system in Oklahoma, and our investment in SESH, a pipeline extending from Louisiana to Alabama. CenterPoint Energy and OGE Energy each have 50% of the management interests in Enable GP. Enable GP is the general partner of the Partnership and has no other operating activities. Enable GP is governed by a board made up of two representatives designated by each of CenterPoint Energy and OGE Energy, along with the Partnership’s Chief Executive Officer and three independent board members CenterPoint Energy and OGE Energy mutually agreed to appoint. CenterPoint Energy and OGE Energy also own a 40% and 60% interest, respectively, in the incentive distribution rights held by Enable GP. As of June 30, 2021, CenterPoint Energy held approximately 53.7% or 233,856,623 of the Partnership’s common units, and OGE Energy held approximately 25.5% or 110,982,805 of the Partnership’s common units. Additionally, CenterPoint Energy holds 14,520,000 Series A Preferred Units. The limited partner interests of the Partnership have limited voting rights on matters affecting the business. As such, limited partners do not have rights to elect the Partnership’s general partner on an annual or continuing basis and may not remove Enable GP, its current general partner, without at least a 75% vote by all unitholders, including all units held by the Partnership’s limited partners, and Enable GP and its affiliates, voting together as a single class. As of June 30, 2021, the Partnership owned a 50% interest in SESH. See Note 8 for further discussion of SESH. For the six months ended June 30, 2021, the Partnership owned a 50% ownership in Atoka and consolidated Atoka in the accompanying Condensed Consolidated Financial Statements as EOIT acted as the managing member of Atoka and had control over the operations of Atoka. In addition, the Partnership held a 60% interest in ESCP, which is consolidated in the accompanying Condensed Consolidated Financial Statements as EOCS acted as the managing member of ESCP and had control over the operations of ESCP. Merger Agreement On February 16, 2021, the Partnership and Energy Transfer entered into a Merger Agreement, whereby the Partnership will be acquired by Energy Transfer in an all-equity transaction, including the assumption of debt and other liabilities. Under the terms of the Merger Agreement, which has been unanimously approved by the Boards of Directors of both companies, Partnership common unitholders will receive 0.8595 of an Energy Transfer common unit for each Partnership common unit. Each of the Partnership’s Series A Preferred Units will be exchanged for 0.0265 Series G preferred units of Energy Transfer. The transaction will also include a $10 million cash payment for the Partnership’s general partner. Generally, the Merger, including the receipt of equity consideration by common unitholders is expected to be treated as a tax-free transaction subject to certain exceptions as described in a Registration Statement on Form S-4 filed by Energy Transfer. The transaction, which is expected to close in the second half of 2021, is subject to customary closing conditions. CenterPoint Energy and OGE Energy, who collectively own approximately 79% of the outstanding Partnership common units, delivered their consents to the transaction. The Merger Agreement includes certain customary restrictions on the Partnership until closing of the Merger, such as limitations on distributions, equity issuances, and incurring and prepaying indebtedness. If the Merger does not occur, under certain circumstances, the Partnership may be required to pay Energy Transfer a termination fee of $97.5 million. Until the approval by unitholders and subsequent closing, we must continue to operate the Partnership as a stand-alone company. Basis of Presentation The accompanying Condensed Consolidated Financial Statements and related notes of the Partnership have been prepared pursuant to the rules and regulations of the SEC and GAAP. Pursuant to such rules and regulations, certain disclosures normally included in financial statements prepared in accordance with GAAP have been omitted. The accompanying Condensed Consolidated Financial Statements and related notes should be read in conjunction with the Consolidated Financial Statements and related notes included in our Annual Report. The Condensed Consolidated Financial Statements and the related notes reflect all normal recurring adjustments that are, in the opinion of management, necessary to present fairly the financial position and results of operations for the respective periods. Amounts reported in the Partnership’s Condensed Consolidated Statements of Income are not necessarily indicative of amounts expected for a full-year period due to the effects of, among other things, (a) seasonal fluctuations in demand for energy and energy services, (b) changes in energy commodity prices, (c) timing of maintenance and other expenditures, (d) acquisitions and dispositions of businesses, assets and other interests, and (e) the impact of the ongoing COVID-19 pandemic and the economic effects of the pandemic which have continued to cause significant volatility in natural gas, NGLs and crude oil prices. For a description of the Partnership’s reportable segments, see Note 16. Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. Sales and Retirements of Assets On September 23, 2019, the Partnership entered into an agreement to sell its undivided 1/12th interest in the Bistineau Storage Facility in Louisiana for approximately $19 million. On January 27, 2020, FERC approved the sale. The Partnership closed the sale on April 1, 2020. We did not recognize a gain or loss on this transaction. In April 2020, we sustained damage to an approximately 100-mile gas gathering system in the Ark-La-Tex Basin of our gathering and processing segment. We have ceased operation of this system and are in the process of retiring it. We recognized a loss on retirement of approximately $20 million during the three months ended June 30, 2020, which is included in Operation and maintenance expense in the Condensed Consolidated Statements of Income. Accounts Receivable and Allowance for Doubtful Accounts The Partnership adopted ASU No. 2016-13, “Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments” on January 1, 2020. Upon adoption, the Partnership recognized a $3 million cumulative adjustment to Partners’ Equity and a corresponding adjustment to Allowance for doubtful accounts. Accounts receivable are recorded at the invoiced amount and do not typically bear interest. The determination of the allowance for doubtful accounts requires management to make estimates and judgments regarding our customers’ ability to pay. The allowance for doubtful accounts is determined based primarily upon the historical loss-rate method established for various pools of accounts receivables with similar levels of credit risk. The historical loss-rates are then adjusted, as necessary, based on current conditions and forecast information that could result in future uncollectable amounts. On an ongoing basis, we evaluate our customers’ financial strength and liquidity based on aging of accounts receivable, payment history, and review of other relevant information, including ratings agency credit ratings and alerts, publicly available reports and news releases, and bank and trade references. It is the policy of management to review the outstanding accounts receivable and other receivable balances within other assets at least quarterly, giving consideration to credit losses, the aging of receivables, specific customer circumstances that may impact their ability to pay the amounts due and current and forecast economic conditions over the assets contractual lives. The following table summarizes the required allowance for doubtful accounts. June 30, 2021 December 31, 2020 (In millions) Accounts receivable $ 3 $ 1 Other current assets 2 3 Total Allowance for doubtful accounts $ 5 $ 4 Inventory Natural gas inventory is held, through the transportation and storage segment, to provide operational support for pipeline deliveries and to manage leased intrastate storage capacity. Natural gas liquids inventory is held, through the gathering and processing segment, due to timing differences between the production of certain natural gas liquids and ultimate sale to third parties. Natural gas and natural gas liquids inventory is valued using moving average cost and is subsequently recorded at the lower of cost or net realizable value. The Partnership recorded write-downs to net realizable value related to natural gas and natural gas liquids inventory of zero and $1 million during the three months ended June 30, 2021 and 2020, respectively, and $1 million and $7 million during the six months ended June 30, 2021 and 2020, respectively. Impairment of Long-Lived Assets (including Intangible Assets) The Partnership periodically evaluates long-lived assets, including property, plant and equipment, and specifically identifiable intangibles other than goodwill, when events or changes in circumstances indicate that the carrying value of these assets may not be recoverable. The determination of whether an impairment has occurred is based on an estimate of undiscounted cash flows attributable to the assets, as compared to the carrying value of the assets. For more information, see Note 7. Impairment of Goodwill The Partnership assesses its goodwill for impairment annually on October 1st, or more frequently if events or changes in circumstances indicate that the carrying value of goodwill may not be recoverable. Goodwill is assessed for impairment by comparing the fair value of the reporting unit with its book value, including goodwill. The Partnership utilizes the market or income approaches to estimate the fair value of the reporting unit, also giving consideration to the alternative cost approach. Under the market approach, historical and current year forecasted cash flows are multiplied by a market multiple to determine fair value. Under the income approach, anticipated cash flows over a period of years plus a terminal value are discounted to present value using appropriate discount rates. The resulting fair value of the reporting unit is then compared to the carrying amount of the reporting unit and an impairment charge is recorded to goodwill for the difference. The Partnership performs its goodwill impairment testing at the reporting unit, which is one level below the transportation and storage and gathering and processing reportable segment level. For more information, see Note 7. Capitalization of Interest and Allowance for Funds Used During Construction Capitalized interest represents the approximate net composite interest cost of borrowed funds used for construction of assets other than those assets regulated by FERC. Allowance for funds used during construction (AFUDC) is separated into two components, borrowed funds (debt AFUDC) and equity funds (equity AFUDC). AFUDC is calculated under guidelines prescribed by FERC, and represents the approximate net composite interest cost of borrowed funds and a reasonable return on the equity funds used for construction of FERC regulated assets. Although equity AFUDC increases both utility plant and earnings, it is realized in cash when the assets are included in rates for entities that apply guidance for accounting for regulated operations. Interest and AFUDC are capitalized as a component of projects under construction and will be amortized over the assets’ estimated useful lives. Capitalized interest and the borrowed funds component of AFUDC are recognized as an offset to Interest expense and the equity funds component of AFUDC is recognized in Other, net on the Condensed Consolidated Statements of Income. The Partnership capitalized interest and combined debt and equity AFUDC of $6 million and $1 million during the three months ended June 30, 2021 and 2020, respectively, and $7 million and $1 million during the six months ended June 30, 2021 and 2020, respectively.

New Accounting Pronouncements

New Accounting Pronouncements	6 Months Ended
	Jun. 30, 2021
Accounting Changes and Error Corrections [Abstract]
New Accounting Pronouncements	New Accounting Pronouncements Reference Rate Reform In March 2020, the FASB issued ASU No. 2020-04, “Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting.” This standard provides optional guidance, for a limited time, to ease the potential burden in accounting for or recognizing the effects of reference rate reform on financial reporting. The standard was effective upon issuance and generally can be applied through December 31, 2022. The Partnership adopted ASU 2020-04 during the year ended December 31, 2020. The implementation had no material impact on the Consolidated Financial Statements and related disclosures. In January 2021, the FASB issued ASU No. 2021-01, “Reference Rate Reform (Topic 848): Scope.” This standard clarifies that certain optional expedients and exceptions in ASC 848 for contract modifications and hedge accounting apply to derivatives that are affected by the discounting transition. ASU 2021-01 also amends the expedients and exceptions in ASC 848 to capture the incremental consequences of the scope clarification and to tailor the existing guidance to derivative instruments affected by the discounting transition. ASU 2021-01 was effective upon issuance and generally can be applied through December 31, 2022. The Partnership adopted ASU 2021-01 during the first quarter of 2021. The implementation had no material impact on the Condensed Consolidated Financial Statements and related disclosures.

Revenue

Revenue	6 Months Ended
	Jun. 30, 2021
Revenue from Contract with Customer [Abstract]
Revenue	Revenues The following tables disaggregate total revenues by major source from contracts with customers and the gain (loss) on derivative activity for the three and six months ended June 30, 2021 and 2020. Three Months Ended June 30, 2021 Gathering and Transportation Eliminations Total (In millions) Revenues: Product sales: Natural gas $ 91 $ 133 $ (131) $ 93 Natural gas liquids 361 5 (5) 361 Condensate 35 — — 35 Total revenues from natural gas, natural gas liquids, and condensate 487 138 (136) 489 Loss on derivative activity (26) (3) — (29) Total Product sales $ 461 $ 135 $ (136) $ 460 Service revenues: Demand revenues $ 31 $ 107 $ — $ 138 Volume-dependent revenues 181 11 (3) 189 Total Service revenues $ 212 $ 118 $ (3) $ 327 Total Revenues $ 673 $ 253 $ (139) $ 787 Three Months Ended June 30, 2020 Gathering and Transportation Eliminations Total (In millions) Revenues: Product sales: Natural gas $ 47 $ 57 $ (53) $ 51 Natural gas liquids 143 3 (3) 143 Condensate 7 — — 7 Total revenues from natural gas, natural gas liquids, and condensate 197 60 (56) 201 Loss on derivative activity (4) (1) — (5) Total Product sales $ 193 $ 59 $ (56) $ 196 Service revenues: Demand revenues $ 34 $ 113 $ — $ 147 Volume-dependent revenues 164 11 (3) 172 Total Service revenues $ 198 $ 124 $ (3) $ 319 Total Revenues $ 391 $ 183 $ (59) $ 515 Six Months Ended June 30, 2021 Gathering and Transportation Eliminations Total (In millions) Revenues: Product sales: Natural gas $ 203 $ 463 $ (261) $ 405 Natural gas liquids 658 8 (8) 658 Condensate 67 — — 67 Total revenues from natural gas, natural gas liquids, and condensate 928 471 (269) 1,130 Loss on derivative activity (39) (4) — (43) Total Product sales $ 889 $ 467 $ (269) $ 1,087 Service revenues: Demand revenues $ 57 $ 234 $ — $ 291 Volume-dependent revenues 351 34 (6) 379 Total Service revenues $ 408 $ 268 $ (6) $ 670 Total Revenues $ 1,297 $ 735 $ (275) $ 1,757 Six Months Ended June 30, 2020 Gathering and Transportation Eliminations Total (In millions) Revenues: Product sales: Natural gas $ 103 $ 130 $ (113) $ 120 Natural gas liquids 315 5 (5) 315 Condensate 34 — — 34 Total revenues from natural gas, natural gas liquids, and condensate 452 135 (118) 469 Gain (loss) on derivative activity 16 (1) — 15 Total Product sales $ 468 $ 134 $ (118) $ 484 Service revenues: Demand revenues $ 73 $ 255 $ — $ 328 Volume-dependent revenues 327 28 (4) 351 Total Service revenues $ 400 $ 283 $ (4) $ 679 Total Revenues $ 868 $ 417 $ (122) $ 1,163 MRT Rate Case Settlements In June 2018, MRT filed a general NGA rate case (the 2018 Rate Case), and in October 2019, MRT filed a second rate case (the 2019 Rate Case). MRT began collecting the rates proposed in the 2018 Rate Case, subject to refund, on January 1, 2019. On March 26, 2020, FERC issued an order approving settlements filed in the 2018 Rate Case and the 2019 Rate Case. Upon issuance of the order and approval of the settlement of the MRT rate cases, the Partnership recognized $17 million of revenues from amounts previously held in reserve related to transportation and storage services performed in 2019. In May 2020, $21 million previously held in reserve was refunded to customers, which was inclusive of interest. Accounts Receivable The following table summarizes the components of accounts receivable, net of allowance for doubtful accounts. June 30, 2021 December 31, 2020 (In millions) Accounts Receivable: Customers $ 301 $ 245 Contract assets (1) 31 12 Non-customers 6 6 Total Accounts Receivable (2) $ 338 $ 263 ____________________ (1) Contract assets reflected in Total Accounts Receivable include accrued minimum volume commitments. Contract assets are primarily attributable to revenues associated with estimated shortfall volumes on certain annual minimum volume commitment arrangements. Total Accounts Receivable does not include contract assets related to firm service transportation contracts with tiered rates of $11 million as of June 30, 2021 and $9 million as of December 31, 2020, which are reflected in Other Assets. (2) Total Accounts Receivable includes Accounts receivable, net of allowance for doubtful accounts and Accounts receivable—affiliated companies. Contract Liabilities Our contract liabilities primarily consist of prepayments received from customers for which the good or service has not yet been provided in connection with the prepayment. The table below summarizes the change in the contract liabilities. June 30, 2021 December 31, 2020 (In millions) Deferred revenues, beginning of period (1) $ 44 $ 48 Amounts recognized in revenues related to the beginning balance (19) (25) Net additions 20 21 Deferred revenues, end of period (1) $ 45 $ 44 ____________________ (1) Deferred revenues includes deferred revenue — affiliated companies. This amount is included in Other current liabilities and Other long-term liabilities. The table below summarizes the timing of recognition of these contract liabilities as of June 30, 2021. 2021 2022 2023 2024 2025 and After (In millions) Deferred revenues (1) $ 22 $ 7 $ 7 $ 7 $ 2 ____________________ (1) Deferred revenues includes deferred revenue — affiliated companies. This amount is included in Other current liabilities and Other long-term liabilities. Remaining Performance Obligations Our remaining performance obligations consist primarily of firm arrangements and minimum volume commitment arrangements. Upon completion of the performance obligations associated with these arrangements, customers are invoiced and revenue is recognized as Service revenues in the Condensed Consolidated Statements of Income. The table below summarizes the timing of recognition of the remaining performance obligations as of June 30, 2021. 2021 2022 2023 2024 2025 and After (In millions) Transportation and Storage $ 221 $ 404 $ 355 $ 265 $ 959 Gathering and Processing 60 122 121 101 213 Total remaining performance obligations $ 281 $ 526 $ 476 $ 366 $ 1,172

Leases

Leases	6 Months Ended
	Jun. 30, 2021
Leases [Abstract]
Leases	Leases The table below summarizes the operating leases included in the Condensed Consolidated Balance Sheets. Balance Sheet Location June 30, 2021 December 31, 2020 (In millions) Operating lease asset Other Assets $ 23 $ 25 Total right-of-use assets $ 23 $ 25 Operating lease liabilities Other Current Liabilities $ 4 $ 4 Operating lease liabilities Other Liabilities 22 24 Total lease liabilities $ 26 $ 28 As of June 30, 2021, all lease obligations outstanding were classified as operating leases. Therefore, all cash flows are reflected in Cash Flows from Operating Activities. The following table presents the Partnership’s rental costs associated with field equipment and buildings. Three Months Ended June 30, Six Months Ended 2021 2020 2021 2020 (In millions) Rental Costs: Field equipment $ 2 $ 4 $ 5 $ 9 Office space 2 1 3 2 As of June 30, 2021, the weighted average remaining lease term is 6.3 years and the weighted average discount rate is 5.49%. The following table presents the Partnership’s lease cost. Three Months Ended June 30, Six Months Ended 2021 2020 2021 2020 (In millions) Lease Cost: Operating lease cost $ 2 $ 1 $ 3 $ 3 Short-term lease cost 2 4 4 7 Variable lease cost — — 1 1 Total Lease Cost $ 4 $ 5 $ 8 $ 11 All lease costs were included in the gathering and processing reportable segment during the three and six months ended June 30, 2021 and 2020 . Under ASC 842, as of June 30, 2021 , the Partnership has operating lease obligations expiring at various dates. Undiscounted cash flows for operating lease liabilities are as follows: Non-cancellable operating leases (In millions) Year Ending December 31, 2021 - remainder $ 3 2022 5 2023 5 2024 4 2025 3 2026 2 After 2026 6 Total 28 Less: impact of the applicable discount rate 2 Total lease liabilities $ 26

Earnings Per Limited Partner Un

Earnings Per Limited Partner Unit	6 Months Ended
	Jun. 30, 2021
Earnings Per Share [Abstract]
Earnings Per Limited Partner Unit	Earnings Per Limited Partner Unit The following table illustrates the Partnership’s calculation of earnings per unit for common units. Three Months Ended June 30, Six Months Ended 2021 2020 2021 2020 (In millions, except per unit data) Net income $ 88 $ 44 $ 253 $ 149 Net income (loss) attributable to noncontrolling interest 1 — 2 (7) Series A Preferred Unit distributions 8 9 17 18 Net income available to common units $ 79 $ 35 $ 234 $ 138 Net income allocable to common units $ 79 $ 35 $ 234 $ 138 Dilutive effect of Series A Preferred Unit distributions — — 17 18 Diluted net income allocable to common units $ 79 $ 35 $ 251 $ 156 Basic weighted average number of common units outstanding (1) 438 437 438 437 Dilutive effect of Series A Preferred Units — — 41 79 Dilutive effect of performance units (2) 1 — — — Diluted weighted average number of common units outstanding 439 437 479 516 Basic and diluted earnings per unit Basic $ 0.18 $ 0.08 $ 0.53 $ 0.32 Diluted $ 0.18 $ 0.08 $ 0.52 $ 0.30 ____________________ (1) Basic weighted average number of outstanding common units includes approximately three million and two million time-based phantom units for the three months ended June 30, 2021 and 2020, respectively, and two million time-based phantom units for each of the six months ended June 30, 2021 and 2020, respectively. (2) The dilutive effect of the performance unit awards was less than $0.01 per unit during the three months ended June 30, 2020 and the six months ended June 30, 2021 and 2020.

Partners' Equity

Partners' Equity	6 Months Ended
	Jun. 30, 2021
Equity [Abstract]
Partners' Equity	Partners’ Equity The Partnership Agreement requires that, within 60 days after the end of each quarter, the Partnership distribute all of its available cash (as defined in the Partnership Agreement) to unitholders of record on the applicable record date. The Partnership paid or has authorized payment of the following cash distributions to common unitholders, as applicable, during 2021 and 2020 (in millions, except for per unit amounts): Three Months Ended Record Date Payment Date Per Unit Distribution Total Cash Distribution June 30, 2021 (1) August 12, 2021 August 24, 2021 $ 0.16525 $ 72 March 31, 2021 May 13, 2021 May 25, 2021 $ 0.16525 $ 72 December 31, 2020 February 22, 2021 March 1, 2021 $ 0.16525 $ 72 September 30, 2020 November 17, 2020 November 24, 2020 $ 0.16525 $ 72 June 30, 2020 August 18, 2020 August 25, 2020 $ 0.16525 $ 72 March 31, 2020 May 19, 2020 May 27, 2020 $ 0.16525 $ 72 _____________________ (1) The Board of Directors declared a $0.16525 per common unit cash distribution on July 30, 2021, to be paid on August 24, 2021 to common unitholders of record at the close of business on August 12, 2021. Holders of the Series A Preferred Units receive a quarterly cash distribution on a non-cumulative basis if and when declared by the General Partner, and subject to certain adjustments, equal to an annual rate of 10% on the stated liquidation preference of $25.00 from the date of original issue, February 18, 2016, to, but not including, the five-year anniversary of the original issue date, February 18, 2021. Thereafter, the holders receive a quarterly cash distribution based on a percentage of the stated liquidation preference equal to the sum of the three-month LIBOR plus 8.5%, which is included for each relevant period in the table below. The Partnership paid or has authorized payment of the following cash distributions to holders of the Series A Preferred Units during 2021 and 2020 (in millions, except for per unit amounts): Three Months Ended Record Date Payment Date Distribution Rate Per Unit Distribution Total Cash Distribution June 30, 2021 (1) July 30, 2021 August 13, 2021 8.7016 % $ 0.5439 $ 8 March 31, 2021 (2) April 26, 2021 May 14, 2021 8.7375 % $ 0.5873 $ 9 December 31, 2020 February 12, 2021 February 12, 2021 10.0 % $ 0.625 $ 9 September 30, 2020 November 3, 2020 November 13, 2020 10.0 % $ 0.625 $ 9 June 30, 2020 August 4, 2020 August 14, 2020 10.0 % $ 0.625 $ 9 March 31, 2020 May 5, 2020 May 15, 2020 10.0 % $ 0.625 $ 9 _____________________ (1) The Board of Directors declared a $0.5439 per Series A Preferred Unit cash distribution on July 30, 2021, to be paid on August 13, 2021, to Series A Preferred unitholders of record at the close of business on July 30, 2021. (2) The distribution rate for the three months ended March 31, 2021 reflects 10% through February 18, 2021, and the sum of the three-month LIBOR plus 8.5% for the remaining days in the period.

Impairment of Property, Plant a

Impairment of Property, Plant and Equipment and Goodwill	6 Months Ended
	Jun. 30, 2021
Impairment of Property, Plant and Equipment and Goodwill [Abstract]
Impairment of Property, Plant and Equipment and Goodwill [Text Block]	(7) Impairments of Property, Plant and Equipment and Goodwill Impairment of Property, Plant and Equipment The Partnership periodically evaluates property, plant and equipment for impairment when events or changes in circumstances indicate that the carrying value of these assets may not be recoverable. The determination of whether an impairment has occurred is based on an estimate of undiscounted cash flows attributable to the assets, as compared to the carrying value of the assets. Due to decreases in natural gas and NGL market prices during 2020 as a result of the ongoing COVID-19 pandemic and the economic effects of the pandemic, together with the dispute over crude oil production levels between Russia and members of OPEC led by Saudi Arabia, as of March 31, 2020, management reassessed the carrying value of the Atoka assets, in which the Partnership owns a 50% interest in the consolidated joint venture, which is a component of the gathering and processing segment. Based on forecasted future undiscounted cash flows, management determined that the carrying value of the Atoka assets were not fully recoverable. The Partnership utilized the income approach (generally accepted valuation approach) to estimate the fair value of these assets. The primary inputs were forecasted cash flows and the discount rate. The fair value measurement is based on inputs that are not observable in the market and thus represent Level 3 inputs. Applying a discounted cash flow model to the property, plant and equipment, the Partnership recognized a $16 million impairment, which is included in Impairments of property, plant and equipment and goodwill on the Condensed Consolidated Statements of Income during the six months ended June 30, 2020. Impairment of Goodwill In the fourth quarter of 2017, as a result of the acquisition of ETGP, the Partnership recorded $12 million of goodwill associated with the Ark-La-Tex Basin reporting unit, included in the gathering and processing reportable segment. The Partnership tests its goodwill for impairment annually on October 1st, or more frequently if events or changes in circumstances indicate that the carrying value of goodwill may not be recoverable. Goodwill is assessed for impairment by comparing the fair value of the reporting unit with its book value, including goodwill. During 2020, the commodity price declines due to the existing oversupply of crude oil, NGLs and natural gas were exacerbated by t he ongoing COVID-19 pandemic and the economic effects of the pandemic, in addition to the dispute over crude oil production levels between Russia and members of OPEC led by Saudi Arabia in the first quarter . Despite the subsequent agreement in April 2020 by a coalition of nations including Russia and Saudi Arabia to reduce production of crude oil, the price of NGLs and crude oil had remained significantly lower than pre-pandemic levels. Amid such crude oil, NGL and natural gas price declines, producers had been cutting back spending and shifting their focus from emphasizing reserves growth, to increasing net cash flows and reducing outstanding debt, which consequently resulted in a decrease in rig count and in forecasted producer activity in the Ark-La-Tex Basin reporting unit during the first quarter of 2020. At the same time, unit prices and market multiples for midstream companies with gathering and processing operations had dropped to their lowest levels in the last three years. Due to the continuing decrease in forward commodity prices, the reduction in forecasted producer activities, the resulting decrease in our forecasted cash flows and the increase in the weighted average cost of capital, the Partnership determined that the fair value of the goodwill associated with our Ark-La-Tex Basin reporting unit would more likely than not be impaired. As a result, the Partnership performed a quantitative test for our goodwill and determined that the carrying value of the Ark-La-Tex Basin reporting unit exceeded its fair value and that goodwill associated with the Ark-La-Tex Basin was completely impaired in the amount of $12 million. The impairment is included in Impairments of property, plant and equipment and goodwill on the Condensed Consolidated Statements of Income for the six months ended June 30, 2020. The Partnership had no goodwill recorded as of June 30, 2021 and December 31, 2020.

Investment in Equity Method Aff

Investment in Equity Method Affiliate	6 Months Ended
	Jun. 30, 2021
Equity Method Investments and Joint Ventures [Abstract]
Investment in Equity Method Affiliate	Investment in Equity Method Affiliate The Partnership uses the equity method of accounting for investments in entities in which it has an ownership interest between 20% and 50% and exercises significant influence. SESH is owned 50% by Enbridge, Inc. and 50% by the Partnership. Pursuant to the terms of the SESH LLC Agreement, if, at any time, CenterPoint Energy has a right to receive less than 50% of our distributions through its interest in the Partnership and its economic interest in Enable GP, or does not have the ability to exercise certain control rights, Enbridge, Inc. may, under certain circumstances, have the right to purchase the Partnership’s interest in SESH at fair market value, subject to certain exceptions. The Partnership shares operations of SESH with Enbridge, Inc. under service agreements. The Partnership is responsible for the field operations of SESH. SESH reimburses each party for actual costs incurred, which are billed based upon a combination of direct charges and allocations. The Partnership billed SESH $3 million and $2 million during the three months ended June 30, 2021 and 2020, respectively, and $5 million and $8 million during the six months ended June 30, 2021 and 2020, respectively, associated with these service agreements. The Partnership includes equity in earnings of equity method affiliate, net under the Other Income (Expense) caption in the Condensed Consolidated Statements of Income. The following table presents the amount of Equity in earnings of equity method affiliate recognized and Distributions from equity method affiliate received. Three Months Ended June 30, Six Months Ended 2021 2020 2021 2020 (In millions) Equity in earnings of equity method affiliate $ — $ 5 $ 1 $ 11 Distributions from equity method affiliate (1) — 9 4 19 ___________________ (1) Distributions from equity method affiliate includes a zero and $5 million return on investment and a zero and $4 million return of investment for the three months ended June 30, 2021 and 2020, respectively. Distributions from equity method affiliate includes a $1 million and $11 million return on investment and a $3 million and $8 million return of investment for the six months ended June 30, 2021 and 2020, respectively. The following table includes the summarized financial information of SESH. Three Months Ended June 30, Six Months Ended 2021 2020 2021 2020 (In millions) Income Statements: Revenues $ 16 $ 28 $ 31 $ 55 Operating income 2 13 6 29 Net income (loss) (1) 10 (2) 21

Debt

Debt	6 Months Ended
	Jun. 30, 2021
Debt Disclosure [Abstract]
Debt	Debt The following table presents the Partnership’s outstanding debt. June 30, 2021 December 31, 2020 Outstanding Principal Discount (1) Total Debt Outstanding Principal Discount (1) Total Debt (In millions) Commercial Paper $ 171 $ — $ 171 $ 250 $ — $ 250 Revolving Credit Facility — — — — — — 2019 Term Loan Agreement 800 — 800 800 — 800 2024 Notes 600 — 600 600 — 600 2027 Notes 700 (2) 698 700 (2) 698 2028 Notes 800 (4) 796 800 (5) 795 2029 Notes 547 (1) 546 547 (1) 546 2044 Notes 531 — 531 531 — 531 Total debt $ 4,149 $ (7) $ 4,142 $ 4,228 $ (8) $ 4,220 Less: Short-term debt (2) 171 250 Less: Current portion of long-term debt (3) 800 — Less: Unamortized debt expense (4) 18 19 Total long-term debt $ 3,153 $ 3,951 ____________________ (1) Unamortized discount on long-term debt is amortized over the life of the respective debt. (2) Short-term debt includes $171 million and $250 million of outstanding commercial paper as of June 30, 2021 and December 31, 2020, respectively. (3) As of June 30, 2021, Current portion of long-term debt included $800 million outstanding balance of the 2019 Term Loan Agreement. (4) As of June 30, 2021 and December 31, 2020, there was an additional $2 million and $3 million, respectively, of unamortized debt expense related to the Revolving Credit Facility included in Other assets, not included above. Commercial Paper The Partnership has a commercial paper program, pursuant to which the Partnership is authorized to issue up to $1.4 billion of commercial paper. The commercial paper program is supported by our Revolving Credit Facility, and outstanding commercial paper effectively reduces our borrowing capacity thereunder. There were $171 million and $250 million outstanding under our commercial paper program at June 30, 2021 and December 31, 2020 , respectively. A s of June 30, 2021, the weighted average interest rate for the outstanding commercial paper was 0.42%. Revolving Credit Facility The Partnership’s Revolving Credit Facility is a $1.75 billion, five-year senior unsecured revolving credit facility, which under certain circumstances may be increased from time to time up to an additional $875 million. The Revolving Credit Facility is scheduled to mature on April 6, 2023, subject to an extension option, which could be exercised two times to extend the term of the Revolving Credit Facility, in each case, for an additional one-year term. As of June 30, 2021, there were no principal advances, $3 million letters of credit outstanding and our available borrowing capacity was approximately $1.2 billion under our Revolving Credit Facility. The Revolving Credit Facility provides that outstanding borrowings bear interest at the LIBOR and/or an alternate base rate, at the Partnership’s election, plus an applicable margin. The applicable margin is based on the Partnership’s designated credit ratings from S&P, Moody’s and Fitch Ratings. As of June 30, 2021, the applicable margin for LIBOR-based borrowings under the Revolving Credit Facility was 1.50% based on the Partnership’s credit ratings. In addition, the Revolving Credit Facility requires the Partnership to pay a fee on unused commitments. The commitment fee is based on the Partnership’s credit ratings. As of June 30, 2021, the commitment fee under the restated Revolving Credit Facility was 0.20% per annum based on the Partnership’s credit ratings. The commitment fee is recorded as interest expense in the Partnership’s Condensed Consolidated Statements of Income. 2019 Term Loan Agreement On January 29, 2019, the Partnership entered into an unsecured term loan agreement with Bank of America, N.A., as administrative agent, and the several lenders thereto. As of June 30, 2021, there was $800 million outstanding under the 2019 Term Loan Agreement. The 2019 Term Loan Agreement has a scheduled maturity date of January 29, 2022, but contains an option, which may be exercised up to two times, to extend the maturity date for an additional one-year term. The 2019 Term Loan Agreement provides that outstanding borrowings bear interest at the eurodollar rate and/or an alternate base rate, at the Partnership’s election, plus an applicable margin. The applicable margin is based on the Partnership’s credit ratings. The applicable margin shall equal, (1) in the case of interest rates determined by reference to the eurodollar rate, between 0.75% and 1.50% per annum and (2) in the case of interest rates determined by reference to the alternate base rate, between 0% and 0.50% per annum. As of June 30, 2021, the applicable margin for LIBOR-based advances under the 2019 Term Loan Facility was 1.25% based on the Partnership’s credit ratings. As of June 30, 2021, the weighted average interest rate of the 2019 Term Loan Agreement was 2.07%, including the impact of the associated interest rate derivatives designated as hedging instruments for accounting purposes. Senior Notes As of June 30, 2021, the Partnership’s debt included the 2024 Notes, 2027 Notes, 2028 Notes, 2029 Notes and 2044 Notes, which had $7 million of unamortized discount and $18 million of unamortized debt expense at June 30, 2021, resulting in effective interest rates of 4.01%, 4.56%, 5.19%, 4.30% and 5.08%, respectively, during the six months ended June 30, 2021. In March 2020, the Partnership’s EOIT Senior Notes matured and were paid using proceeds from the Revolving Credit Facility. During the three months ended June 30, 2020, the Partnership repurchased $22 million aggregate principal amount of the 2029 Notes and 2044 Notes in open market transactions for approximately $17 million plus accrued interest, which resulted in a $5 million gain on extinguishment of debt. The gain is included in Other, net in the Condensed Consolidated Statements of Income. As of June 30, 2021, the Partnership was in compliance with all of its debt agreements, including financial covenants.

Derivative Instruments and Hedg

Derivative Instruments and Hedging Activities	6 Months Ended
	Jun. 30, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments and Hedging Activities	Derivative Instruments and Hedging Activities The primary risks managed using derivative instruments are commodity price and interest rate risks. Derivatives Not Designated as Hedging Instruments Derivative instruments not designated as hedging instruments for accounting purposes are utilized to manage the Partnership’s exposure to commodity price risk. For derivative instruments not designated as hedging instruments, the gain or loss on the derivative is recognized currently in earnings. Quantitative Disclosures Related to Derivative Instruments Not Designated as Hedging Instruments The following table presents the Partnership’s derivative instruments that were not designated as hedging instruments for accounting purposes. June 30, 2021 December 31, 2020 Gross Notional Volume Purchases Sales Purchases Sales Natural gas— TBtu (1) Financial fixed futures/swaps — 8 — 18 Financial basis futures/swaps — 22 — 27 Financial swaptions (2) — 4 — 7 Physical purchases/sales — — — — Crude oil (for condensate)— MBbl (3) Financial futures/swaps — 270 — 465 Financial swaptions (2) — 90 — 90 Natural gas liquids— MBbl (4) Financial futures/swaps 45 525 855 1,210 Financial options — 15 — 45 ____________________ (1) As of June 30, 2021, 98.7% of the natural gas contracts had durations of one year or less and 1.3% had durations of more than one year and less than two years. As of December 31, 2020, 95.7% of the natural gas contracts had durations of one year or less and 4.3% had durations of more than one year and less than two years. (2) The notional volume contains a combined derivative instrument consisting of a fixed price swap and a sold option, which gives the counterparties the right, but not the obligation, to increase the notional volume hedged under the fixed price swap until the option expiration date. The notional volume represents the volume prior to option exercise. (3) As of June 30, 2021, 91.7% of the crude oil (for condensate) contracts had durations of one year or less and 8.3% had durations of more than one year and less than two years. As of December 31, 2020, 100.0% of the crude oil (for condensate) contracts had durations of one year or less. (4) As of June 30, 2021, 94.9% of the natural gas liquids contracts had durations of one year or less and 5.1% had durations of more than one year and less than two years. As of December 31, 2020, 100.0% of the natural gas liquids contracts had durations of one year or less. Derivatives Designated as Hedging Instruments Derivative instruments designated as hedging instruments for accounting purposes are utilized in managing the Partnership’s interest rate risk exposures. Quantitative Disclosures Related to Derivative Instruments Designated as Hedging Instruments The following table presents the Partnership’s derivative instruments that were designated as hedging instruments for accounting purposes. June 30, 2021 December 31, 2020 Gross Notional Value (In millions) Interest rate swaps $ 300 $ 300 Balance Sheet Presentation Related to Derivative Instruments The following table presents the fair value of the derivative instruments that are included in the Partnership’s Condensed Consolidated Balance Sheets that were not designated as hedging instruments for accounting purposes. June 30, 2021 December 31, 2020 Fair Value Instrument Balance Sheet Location Assets Liabilities Assets Liabilities (In millions) Natural gas Financial futures/swaps Other Current $ — $ 9 $ 2 $ 2 Financial swaptions Other Current — 6 1 2 Crude oil (for condensate) Financial futures/swaps Other Current — 7 1 13 Financial swaptions Other Current — 1 — — Financial swaptions Other — 1 — — Natural gas liquids Financial futures/swaps Other Current 4 10 15 3 Financial swaptions Other Current — 1 — 1 Total gross commodity derivatives (1) $ 4 $ 35 $ 19 $ 21 _____________________ (1) See Note 11 for a reconciliation of the Partnership’s commodity derivatives fair value to the Partnership’s Condensed Consolidated Balance Sheets as of June 30, 2021 and December 31, 2020. The following table presents the fair value of the derivative instruments that are included in the Partnership’s Condensed Consolidated Balance Sheets that were designated as hedging instruments for accounting purposes. June 30, 2021 December 31, 2020 Fair Value Instrument Balance Sheet Location Assets Liabilities Assets Liabilities (In millions) Interest rate swaps (1) Other Current $ — $ 3 $ — $ 6 _____________________ (1) All interest rate derivative instruments that were designated as cash flow hedges are considered Level 2 as of June 30, 2021 and December 31, 2020. Income Statement Presentation Related to Derivative Instruments The following table presents the effect of derivative instruments on the Partnership’s Condensed Consolidated Statements of Income. Amounts Recognized in Income Three Months Ended June 30, Six Months Ended 2021 2020 2021 2020 (In millions) Natural gas Financial futures/swaps gains (losses) $ (11) $ (1) $ (13) $ 3 Financial swaptions losses (5) (1) (5) (2) Physical purchases/sales gains (losses) — — — 1 Crude oil (for condensate) Financial futures/swaps gains (losses) (6) (7) (12) 12 Financial swaptions gains (losses) (1) (2) (2) 2 Natural gas liquids Financial futures/swaps gains (losses) (6) 6 (11) (1) Total $ (29) $ (5) $ (43) $ 15 For derivatives not designated as hedges in the tables above, amounts recognized in income for the periods ended June 30, 2021 and 2020, if any, are reported in Product sales. The following table presents the components of gain (loss) on derivative activity in the Partnership’s Condensed Consolidated Statements of Income. Three Months Ended June 30, Six Months Ended 2021 2020 2021 2020 (In millions) Change in fair value of commodity derivatives $ (19) $ (12) $ (29) $ (2) Realized gains (losses) on commodity derivatives (10) 7 (14) 17 Gains (losses) on commodity derivative activity $ (29) $ (5) $ (43) $ 15 The following table presents the effect of derivative instruments that were designated as hedging instruments on the Partnership’s Condensed Consolidated Statements of Income. Amounts Recognized in Income Three Months Ended June 30, Six Months Ended 2021 2020 2021 2020 (In millions) Interest rate swaps losses $ (2) $ (1) $ (3) $ (1) Interest rate derivatives designated as hedges are recognized in income once settled. Settlement amounts recognized in income for the periods ended June 30, 2021 and 2020 are reported in Interest expense. Credit-Risk Related Contingent Features in Derivative Instruments In the event Moody’s or S&P were to lower the Partnership’s senior unsecured debt rating to a below investment grade rating, the Partnership could be required to provide additional credit assurances to third parties, which could include letters of credit or cash collateral to satisfy its obligation under its financial and physical contracts relating to derivative instruments that are in a net liability position. As of June 30, 2021, under these obligations, the Partnership had posted $1 million of cash collateral related to natural gas swaps and swaptions, crude oil swaps and swaptions and NGL swaps and $6 million of additional collateral would be required to be posted by the Partnership in the event of a credit ratings downgrade to a below investment grade rating. In certain situations where the Partnership’s credit rating is lowered by Moody’s or S&P, the Partnership could be subject to an early termination event related to certain derivative instruments, which could result in a cash settlement of the instruments at market values on the date of such early termination.

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements Certain assets and liabilities are recorded at fair value in the Condensed Consolidated Balance Sheets and are categorized based upon the level of judgment associated with the inputs used to measure their value. The Partnership determines the appropriate level for each financial asset and liability on a quarterly basis and recognizes transfers between levels at the end of the reporting period. For the three and six months ended June 30, 2021, there were no transfers between levels. As of June 30, 2021, there were no contracts classified as Level 3. Estimated Fair Value of Financial Instruments The fair values of all accounts receivable, notes receivable, accounts payable, commercial paper and other such financial instruments on the Condensed Consolidated Balance Sheets are estimated to be approximately equivalent to their carrying amounts due to their short-term nature and have been excluded from the table below. The following table summarizes the fair value and carrying amount of the Partnership’s financial instruments. June 30, 2021 December 31, 2020 Carrying Amount Fair Value Carrying Amount Fair Value (In millions) Debt Revolving Credit Facility (Level 2) (1) $ — $ — $ — $ — 2019 Term Loan Agreement (Level 2) 800 800 800 800 2024 Notes (Level 2) 600 639 600 612 2027 Notes (Level 2) 698 774 698 709 2028 Notes (Level 2) 796 916 795 817 2029 Notes (Level 2) 546 599 546 544 2044 Notes (Level 2) 531 578 531 499 ____________________ (1) Borrowing capacity is effectively reduced by our borrowings outstanding under the commercial paper program. $171 million and $250 million of commercial paper was outstanding as of June 30, 2021 and December 31, 2020, respectively. The fair value of the Partnership’s Revolving Credit Facility, 2019 Term Loan Agreement, 2024 Notes, 2027 Notes, 2028 Notes, 2029 Notes, and 2044 Notes is based on quoted market prices and estimates of current rates available for similar issues with similar maturities and is classified as Level 2 in the fair value hierarchy. Non-Financial Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis Certain assets and liabilities are measured at fair value on a nonrecurring basis; that is, the assets and liabilities are not measured at fair value on an ongoing basis but are subject to fair value adjustments in certain circumstances (e.g., when there is evidence of impairment). As of June 30, 2021, no material fair value adjustments or fair value measurements were required for these non-financial assets or liabilities. Based upon review of forecasted undiscounted cash flows as of June 30, 2021, all of the asset groups were considered recoverable. Based upon review for other than temporary declines in fair value, the investment in equity method affiliate was considered recoverable. Future price declines, throughput declines, contracted capacity declines, cost increases, regulatory or political environment changes and other changes in market conditions, including the oversupply of crude oil, NGLs and natural gas as well as the ongoing COVID-19 pandemic and the economic effects of the pandemic, could reduce forecasted undiscounted cash flows for the asset groups and result in other than temporary declines in the fair value of the investment in equity method affiliate. Contracts with Master Netting Arrangements As of June 30, 2021, the Partnership’s Level 2 interest rate derivatives are recorded as liabilities with no netting adjustments. The following tables summarize the Partnership’s other assets and liabilities that are measured at fair value on a recurring basis. June 30, 2021 Commodity Contracts Gas Imbalances (1) Assets Liabilities Assets (2) Liabilities (3) (In millions) Quoted market prices in active market for identical assets (Level 1) $ — $ 11 $ — $ — Significant other observable inputs (Level 2) 4 24 14 11 Total fair value 4 35 14 11 Netting adjustments (4) (4) — — Total $ — $ 31 $ 14 $ 11 December 31, 2020 Commodity Contracts Gas Imbalances (1) Assets Liabilities Assets (2) Liabilities (3) (In millions) Quoted market prices in active market for identical assets (Level 1) $ 2 $ 14 $ — $ — Significant other observable inputs (Level 2) 17 7 23 16 Total fair value 19 21 23 16 Netting adjustments (19) (19) — — Total $ — $ 2 $ 23 $ 16 ______________________ (1) The Partnership uses the market approach to fair value its gas imbalance assets and liabilities at individual, or where appropriate an average of, current market indices applicable to the Partnership’s operations, not to exceed net realizable value. There were no netting adjustments as of June 30, 2021 and December 31, 2020. (2) Gas imbalance assets exclude fuel reserves for under retained fuel due from shippers of $14 million and $19 million at June 30, 2021 and December 31, 2020, respectively, which fuel reserves are based on the value of natural gas at the time the imbalance was created, and which are not subject to revaluation at fair market value. (3) Gas imbalance liabilities exclude fuel reserves for over retained fuel due to shippers of $3 million and $3 million at June 30, 2021 and December 31, 2020, respectively, which fuel reserves are based on the value of natural gas at the time the imbalance was created, and which are not subject to revaluation at fair market value.

Supplemental Disclosure of Cash

Supplemental Disclosure of Cash Flow Information	6 Months Ended
	Jun. 30, 2021
Supplemental Cash Flow Information [Abstract]
Supplemental Disclosure of Cash Flow Information	Supplemental Disclosure of Cash Flow Information The following table provides information regarding supplemental cash flow information: Six Months Ended June 30, 2021 2020 (In millions) Supplemental Disclosure of Cash Flow Information: Cash Payments: Interest, net of capitalized interest and debt AFUDC $ 81 $ 96 Income taxes, net of refunds (1) 1 Non-cash transactions: Accounts payable related to capital expenditures 6 8 Lease liabilities related to derecognition of right-of-use assets — (5) Impact of adoption of financial instruments-credit losses accounting standard (Note 1) — (3)

Related Party Transactions

Related Party Transactions	6 Months Ended
	Jun. 30, 2021
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions The Partnership’s revenues from affiliated companies accounted for 6% and 7% of total revenues during the six months ended June 30, 2021 and 2020, respectively. The following table presents the amounts of revenues from affiliated companies included in the Partnership’s Condensed Consolidated Statements of Income. Three Months Ended June 30, Six Months Ended 2021 2020 2021 2020 (In millions) Gas transportation and storage service revenues — CenterPoint Energy $ 16 $ 22 $ 43 $ 59 Natural gas product sales — CenterPoint Energy 5 1 5 1 Gas transportation and storage service revenues — OGE Energy 9 10 19 19 Natural gas product sales — OGE Energy 2 — 33 5 Total revenues — affiliated companies $ 32 $ 33 $ 100 $ 84 The following table presents the amounts of natural gas purchased from affiliated companies included in the Partnership’s Condensed Consolidated Statements of Income. Three Months Ended June 30, Six Months Ended 2021 2020 2021 2020 (In millions) Cost of natural gas purchases — CenterPoint Energy $ — $ — $ — $ 1 Cost of natural gas purchases — OGE Energy 12 6 43 14 Total cost of natural gas purchases — affiliated companies $ 12 $ 6 $ 43 $ 15 Corporate services and seconded employees The Partnership receives services and support functions from each of CenterPoint Energy and OGE Energy under services agreements for an initial term that ended on April 30, 2016. The services agreements automatically extend year-to-year at the end of the initial term, unless terminated by the Partnership with at least 90 days’ notice prior to the end of any extension. Additionally, the Partnership may terminate the services agreements at any time with 180 days’ notice, if approved by the Board of Enable GP. The Partnership reimburses CenterPoint Energy and OGE Energy for these services up to annual caps, which for 2021 are both less than $1 million. As of June 30, 2021 , the Partnership had certain employees who are participants under OGE Energy’s defined benefit and retiree medical plans, who will remain seconded to the Partnership, subject to certain termination rights of the Partnership and OGE Energy. The Partnership’s reimbursement of OGE Energy for seconded employee costs arising out of OGE Energy’s defined benefit and retiree medical plans is fixed at actual cost subject to an annual cap of $5 million until secondment is terminated. The following table presents the amounts charged to the Partnership by affiliates for seconded employees, included primarily in Operation and maintenance and General and administrative expenses in the Partnership’s Condensed Consolidated Statements of Income. Three Months Ended June 30, Six Months Ended 2021 2020 2021 2020 (In millions) Seconded Employee Costs — OGE Energy $ 3 $ 5 $ 7 $ 8

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies The Partnership is involved in legal, environmental, tax and regulatory proceedings before various courts, regulatory commissions and governmental agencies regarding matters arising in the ordinary course of business. Some of these proceedings involve substantial amounts. The Partnership regularly analyzes current information and, as necessary, provides accruals for probable liabilities on the eventual disposition of these matters. The Partnership does not expect the disposition of these matters to have a material adverse effect on its financial condition, results of operations or cash flows. On January 1, 2017, the Partnership entered into a 10-year gathering and processing agreement, which became effective on July 1, 2018, with an affiliate of Energy Transfer for deliveries to the Godley Plant in Johnson County, Texas. As of June 30, 2021, the Partnership estimates the remaining associated minimum volume commitment fee to be $159 million. Minimum volume commitment fees are expected to be $10 million for the remainder of 2021, $23 million per year from 2022 through 2027 and $11 million in 2028. On September 13, 2018, the Partnership executed a precedent agreement for the development of the Gulf Run Pipeline, an interstate natural gas transportation project. On January 30, 2019, a final investment decision was made by Golden Pass LNG, the cornerstone shipper for the liquefied natural gas facility to be served by the Gulf Run Pipeline project.

Equity-Based Compensation

Equity-Based Compensation	6 Months Ended
	Jun. 30, 2021
Share-based Payment Arrangement [Abstract]
Equity-Based Compensation	Equity-Based Compensation The following table summarizes the Partnership’s equity-based compensation expense related to performance units and phantom units for the Partnership’s employees and independent directors. Three Months Ended June 30, Six Months Ended 2021 2020 2021 2020 (In millions) Performance units $ 2 $ 2 $ 4 $ 4 Phantom units 2 1 4 3 Total compensation expense $ 4 $ 3 $ 8 $ 7 The following table presents the assumptions related to the performance units granted in 2021. 2021 Number of units granted 1,453,897 Fair value of units granted $ 10.26 Expected distribution yield 12.90 % Expected price volatility 100.00 % Risk-free interest rate 0.27 % Expected life of units (in years) 3 The following table presents the number of phantom units granted and the grant date fair value related to the phantom units granted in 2021. 2021 Phantom Units granted 1,371,001 Fair value of phantom units granted $5.41 - $6.87 Units Outstanding A summary of the activity for the Partnership’s performance units and phantom units applicable to the Partnership’s employees at June 30, 2021 and changes during 2021 are shown in the following table. Performance Units Phantom Units Number Weighted Average Grant-Date Fair Value, Per Unit Number Weighted Average Grant-Date Fair Value, Per Unit (In millions, except unit data) Units outstanding at December 31, 2020 1,765,508 $ 13.10 1,790,845 $ 10.29 Granted (1) 1,453,897 10.26 1,371,001 6.86 Vested (2) (389,817) 17.70 (469,488) 13.07 Forfeited (45,945) 9.94 (119,851) 8.51 Units outstanding at June 30, 2021 2,783,643 $ 11.02 2,572,507 $ 8.03 Aggregate intrinsic value of units outstanding at June 30, 2021 $ 25 $ 23 _____________________ (1) Performance units represents the target number of performance units granted. The actual number of performance units earned, if any, is dependent upon performance and may range from 0% to 200% of the target. (2) Performance units vested as of June 30, 2021 include 389,817 units from the 2018 annual grant, which were approved by the Board of Directors in 2018 and, based on the level of achievement of a performance goal established by the Board of Directors over the performance period of January 1, 2018 through December 31, 2020, no performance units vested. Unrecognized Compensation Cost The following table summarizes the Partnership’s unrecognized compensation cost for its non-vested performance units and phantom units, and the weighted-average periods over which the compensation cost is expected to be recognized. June 30, 2021 Unrecognized Compensation Cost Weighted Average Period for Recognition Performance Units $ 19 2.00 Phantom Units 12 1.84 Total $ 31 As of June 30, 2021, there were 3,118,170 units available for issuance under the long-term incentive plan.

Reportable Segments

Reportable Segments	6 Months Ended
	Jun. 30, 2021
Segment Reporting [Abstract]
Reportable Segments	Reportable Segments The Partnership’s determination of reportable segments considers the strategic operating units under which it manages sales, allocates resources and assesses performance of various products and services to customers in differing regulatory environments. The accounting policies of the reportable segments are the same as those described in the summary of significant accounting policies excerpt in the Partnership’s audited 2020 Notes to Consolidated Financial Statements included in the Annual Report. The Partnership uses operating income as the measure of profit or loss for its reportable segments. The Partnership’s assets and operations are organized into two reportable segments: (i) gathering and processing and (ii) transportation and storage. Our gathering and processing segment primarily provides natural gas gathering and processing services to our producer customers and crude oil, condensate and produced water gathering services to our producer and refiner Financial data for reportable segments are as follows: Three Months Ended June 30, 2021 Gathering and Transportation (1) and Storage Eliminations Total (In millions) Product sales $ 461 $ 135 $ (136) $ 460 Service revenues 212 118 (3) 327 Total Revenues 673 253 (139) 787 Cost of natural gas and natural gas liquids (excluding depreciation and amortization shown separately) 437 128 (139) 426 Operation and maintenance, General and administrative 73 44 (1) 116 Depreciation and amortization 74 29 — 103 Taxes other than income tax 11 7 — 18 Operating income $ 78 $ 45 $ 1 $ 124 Total Assets $ 10,824 $ 5,917 $ (4,982) $ 11,759 Capital expenditures (excluding equity AFUDC) $ 20 $ 51 $ — $ 71 Three Months Ended June 30, 2020 Gathering and Transportation (1) and Storage Eliminations Total (In millions) Product sales $ 193 $ 59 $ (56) $ 196 Service revenues 198 124 (3) 319 Total Revenues 391 183 (59) 515 Cost of natural gas and natural gas liquids (excluding depreciation and amortization shown separately) 176 59 (58) 177 Operation and maintenance, General and administrative 92 45 (1) 136 Depreciation and amortization 74 31 — 105 Taxes other than income tax 11 6 — 17 Operating income $ 38 $ 42 $ — $ 80 Total assets as of December 31, 2020 $ 10,830 $ 5,729 $ (4,830) $ 11,729 Capital expenditures (excluding equity AFUDC) $ 24 $ 24 $ — $ 48 Six Months Ended June 30, 2021 Gathering and Transportation (1) and Storage Eliminations Total (In millions) Product sales $ 889 $ 467 $ (269) $ 1,087 Service revenues 408 268 (6) 670 Total Revenues 1,297 735 (275) 1,757 Cost of natural gas and natural gas liquids (excluding depreciation and amortization shown separately) 835 385 (275) 945 Operation and maintenance, General and administrative 152 86 (1) 237 Depreciation and amortization 148 61 — 209 Taxes other than income tax 22 14 — 36 Operating income $ 140 $ 189 $ 1 $ 330 Total Assets $ 10,824 $ 5,917 $ (4,982) $ 11,759 Capital expenditures (excluding equity AFUDC) $ 41 $ 110 $ — $ 151 Six Months Ended June 30, 2020 Gathering and Transportation (1) and Storage Eliminations Total (In millions) Product sales $ 468 $ 134 $ (118) $ 484 Service revenues 400 283 (4) 679 Total Revenues 868 417 (122) 1,163 Cost of natural gas and natural gas liquids (excluding depreciation and amortization shown separately) 387 137 (121) 403 Operation and maintenance, General and administrative 173 90 (1) 262 Depreciation and amortization 148 61 — 209 Impairments of property, plant and equipment and goodwill 28 — — 28 Taxes other than income tax 22 13 — 35 Operating income $ 110 $ 116 $ — $ 226 Total assets as of December 31, 2020 $ 10,830 $ 5,729 $ (4,830) $ 11,729 Capital expenditures (excluding equity AFUDC) $ 58 $ 44 $ — $ 102 _____________________ (1) See Note 8 for discussion regarding ownership interests in SESH and related equity earnings included in the transportation and storage segment for the three and six months ended June 30, 2021 and 2020.	[1]
[1]	See Note 8 for discussion regarding ownership interests in SESH and related equity earnings included in the transportation and storage segment for the three and six months ended June 30, 2021 and 2020.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization	Organization Enable Midstream Partners, LP (the Partnership) is a Delaware limited partnership whose assets and operations are organized into two reportable segments: (i) gathering and processing and (ii) transportation and storage. Our gathering and processing segment primarily provides natural gas gathering and processing services to our producer customers and crude oil, condensate and produced water gathering services to our producer and refiner customers. The transportation and storage segment provides interstate and intrastate natural gas pipeline transportation and storage services primarily to our producer, power plant, LDC and industrial end-user customers. Our natural gas gathering and processing assets are primarily located in Oklahoma, Texas, Arkansas and Louisiana and serve natural gas production in the Anadarko, Arkoma and Ark-La-Tex Basins. Crude oil gathering assets are located in Oklahoma and serve crude oil production in the SCOOP and STACK plays of the Anadarko Basin and in North Dakota and serve crude oil production in the Bakken Shale formation of the Williston Basin. The Partnership’s natural gas transportation and storage assets consist primarily of an interstate pipeline system extending from western Oklahoma and the Texas Panhandle to Louisiana, an interstate pipeline system extending from Louisiana to Illinois, an intrastate pipeline system in Oklahoma, and our investment in SESH, a pipeline extending from Louisiana to Alabama. CenterPoint Energy and OGE Energy each have 50% of the management interests in Enable GP. Enable GP is the general partner of the Partnership and has no other operating activities. Enable GP is governed by a board made up of two representatives designated by each of CenterPoint Energy and OGE Energy, along with the Partnership’s Chief Executive Officer and three independent board members CenterPoint Energy and OGE Energy mutually agreed to appoint. CenterPoint Energy and OGE Energy also own a 40% and 60% interest, respectively, in the incentive distribution rights held by Enable GP. As of June 30, 2021, CenterPoint Energy held approximately 53.7% or 233,856,623 of the Partnership’s common units, and OGE Energy held approximately 25.5% or 110,982,805 of the Partnership’s common units. Additionally, CenterPoint Energy holds 14,520,000 Series A Preferred Units. The limited partner interests of the Partnership have limited voting rights on matters affecting the business. As such, limited partners do not have rights to elect the Partnership’s general partner on an annual or continuing basis and may not remove Enable GP, its current general partner, without at least a 75% vote by all unitholders, including all units held by the Partnership’s limited partners, and Enable GP and its affiliates, voting together as a single class. As of June 30, 2021, the Partnership owned a 50% interest in SESH. See Note 8 for further discussion of SESH. For the six months ended June 30, 2021, the Partnership owned a 50% ownership in Atoka and consolidated Atoka in the accompanying Condensed Consolidated Financial Statements as EOIT acted as the managing member of Atoka and had control over the operations of Atoka. In addition, the Partnership held a 60% interest in ESCP, which is consolidated in the accompanying Condensed Consolidated Financial Statements as EOCS acted as the managing member of ESCP and had control over the operations of ESCP.
Basis of Presentation	Basis of Presentation The accompanying Condensed Consolidated Financial Statements and related notes of the Partnership have been prepared pursuant to the rules and regulations of the SEC and GAAP. Pursuant to such rules and regulations, certain disclosures normally included in financial statements prepared in accordance with GAAP have been omitted. The accompanying Condensed Consolidated Financial Statements and related notes should be read in conjunction with the Consolidated Financial Statements and related notes included in our Annual Report. The Condensed Consolidated Financial Statements and the related notes reflect all normal recurring adjustments that are, in the opinion of management, necessary to present fairly the financial position and results of operations for the respective periods. Amounts reported in the Partnership’s Condensed Consolidated Statements of Income are not necessarily indicative of amounts expected for a full-year period due to the effects of, among other things, (a) seasonal fluctuations in demand for energy and energy services, (b) changes in energy commodity prices, (c) timing of maintenance and other expenditures, (d) acquisitions and dispositions of businesses, assets and other interests, and (e) the impact of the ongoing COVID-19 pandemic and the economic effects of the pandemic which have continued to cause significant volatility in natural gas, NGLs and crude oil prices.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.
Accounts Receivable and Allowance for Doubtful Accounts	Accounts Receivable and Allowance for Doubtful Accounts The Partnership adopted ASU No. 2016-13, “Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments” on January 1, 2020. Upon adoption, the Partnership recognized a $3 million cumulative adjustment to Partners’ Equity and a corresponding adjustment to Allowance for doubtful accounts.
Inventory	InventoryNatural gas inventory is held, through the transportation and storage segment, to provide operational support for pipeline deliveries and to manage leased intrastate storage capacity. Natural gas liquids inventory is held, through the gathering and processing segment, due to timing differences between the production of certain natural gas liquids and ultimate sale to third parties. Natural gas and natural gas liquids inventory is valued using moving average cost and is subsequently recorded at the lower of cost or net realizable value.
Impairment of Long-lived Assets (including Intangible Assets) and Impairment of Goodwill	Impairment of Long-Lived Assets (including Intangible Assets) The Partnership periodically evaluates long-lived assets, including property, plant and equipment, and specifically identifiable intangibles other than goodwill, when events or changes in circumstances indicate that the carrying value of these assets may not be recoverable. The determination of whether an impairment has occurred is based on an estimate of undiscounted cash flows attributable to the assets, as compared to the carrying value of the assets. For more information, see Note 7. Impairment of Goodwill
Capitalization of Interest and Allowance for Funds Used During Construction	Capitalization of Interest and Allowance for Funds Used During ConstructionCapitalized interest represents the approximate net composite interest cost of borrowed funds used for construction of assets other than those assets regulated by FERC. Allowance for funds used during construction (AFUDC) is separated into two components, borrowed funds (debt AFUDC) and equity funds (equity AFUDC). AFUDC is calculated under guidelines prescribed by FERC, and represents the approximate net composite interest cost of borrowed funds and a reasonable return on the equity funds used for construction of FERC regulated assets. Although equity AFUDC increases both utility plant and earnings, it is realized in cash when the assets are included in rates for entities that apply guidance for accounting for regulated operations. Interest and AFUDC are capitalized as a component of projects under construction and will be amortized over the assets’ estimated useful lives. Capitalized interest and the borrowed funds component of AFUDC are recognized as an offset to Interest expense and the equity funds component of AFUDC is recognized in Other, net on the Condensed Consolidated Statements of Income.
New Accounting Pronouncements	Reference Rate Reform In March 2020, the FASB issued ASU No. 2020-04, “Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting.” This standard provides optional guidance, for a limited time, to ease the potential burden in accounting for or recognizing the effects of reference rate reform on financial reporting. The standard was effective upon issuance and generally can be applied through December 31, 2022. The Partnership adopted ASU 2020-04 during the year ended December 31, 2020. The implementation had no material impact on the Consolidated Financial Statements and related disclosures. In January 2021, the FASB issued ASU No. 2021-01, “Reference Rate Reform (Topic 848): Scope.” This standard clarifies that certain optional expedients and exceptions in ASC 848 for contract modifications and hedge accounting apply to derivatives that are affected by the discounting transition. ASU 2021-01 also amends the expedients and exceptions in ASC 848 to capture the incremental consequences of the scope clarification and to tailor the existing guidance to derivative instruments affected by the discounting transition. ASU 2021-01 was effective upon issuance and generally can be applied through December 31, 2022. The Partnership adopted ASU 2021-01 during the first quarter of 2021. The implementation had no material impact on the Condensed Consolidated Financial Statements and related disclosures.
Derivatives Instruments and Hedging Activities	The primary risks managed using derivative instruments are commodity price and interest rate risks. Derivatives Not Designated as Hedging Instruments Derivative instruments not designated as hedging instruments for accounting purposes are utilized to manage the Partnership’s exposure to commodity price risk. For derivative instruments not designated as hedging instruments, the gain or loss on the derivative is recognized currently in earnings. Derivatives Designated as Hedging Instruments Derivative instruments designated as hedging instruments for accounting purposes are utilized in managing the Partnership’s interest rate risk exposures.
Fair Value Measurements	Certain assets and liabilities are recorded at fair value in the Condensed Consolidated Balance Sheets and are categorized based upon the level of judgment associated with the inputs used to measure their value. The Partnership determines the appropriate level for each financial asset and liability on a quarterly basis and recognizes transfers between levels at the end of the reporting period. For the three and six months ended June 30, 2021, there were no transfers between levels. As of June 30, 2021, there were no contracts classified as Level 3.
Reportable Segments	The Partnership’s determination of reportable segments considers the strategic operating units under which it manages sales, allocates resources and assesses performance of various products and services to customers in differing regulatory environments. The accounting policies of the reportable segments are the same as those described in the summary of significant accounting policies excerpt in the Partnership’s audited 2020 Notes to Consolidated Financial Statements included in the Annual Report. The Partnership uses operating income as the measure of profit or loss for its reportable segments. The Partnership’s assets and operations are organized into two reportable segments: (i) gathering and processing and (ii) transportation and storage. Our gathering and processing segment primarily provides natural gas gathering and processing services to our producer customers and crude oil, condensate and produced water gathering services to our producer and refiner

Accounting Policies (Tables)

Accounting Policies (Tables)	6 Months Ended
	Jun. 30, 2021
Accounting Policies [Abstract]
Accounts Receivable, Allowance for Credit Loss	The following table summarizes the required allowance for doubtful accounts. June 30, 2021 December 31, 2020 (In millions) Accounts receivable $ 3 $ 1 Other current assets 2 3 Total Allowance for doubtful accounts $ 5 $ 4

Revenue (Tables)

Revenue (Tables)	6 Months Ended
	Jun. 30, 2021
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue	The following tables disaggregate total revenues by major source from contracts with customers and the gain (loss) on derivative activity for the three and six months ended June 30, 2021 and 2020. Three Months Ended June 30, 2021 Gathering and Transportation Eliminations Total (In millions) Revenues: Product sales: Natural gas $ 91 $ 133 $ (131) $ 93 Natural gas liquids 361 5 (5) 361 Condensate 35 — — 35 Total revenues from natural gas, natural gas liquids, and condensate 487 138 (136) 489 Loss on derivative activity (26) (3) — (29) Total Product sales $ 461 $ 135 $ (136) $ 460 Service revenues: Demand revenues $ 31 $ 107 $ — $ 138 Volume-dependent revenues 181 11 (3) 189 Total Service revenues $ 212 $ 118 $ (3) $ 327 Total Revenues $ 673 $ 253 $ (139) $ 787 Three Months Ended June 30, 2020 Gathering and Transportation Eliminations Total (In millions) Revenues: Product sales: Natural gas $ 47 $ 57 $ (53) $ 51 Natural gas liquids 143 3 (3) 143 Condensate 7 — — 7 Total revenues from natural gas, natural gas liquids, and condensate 197 60 (56) 201 Loss on derivative activity (4) (1) — (5) Total Product sales $ 193 $ 59 $ (56) $ 196 Service revenues: Demand revenues $ 34 $ 113 $ — $ 147 Volume-dependent revenues 164 11 (3) 172 Total Service revenues $ 198 $ 124 $ (3) $ 319 Total Revenues $ 391 $ 183 $ (59) $ 515 Six Months Ended June 30, 2021 Gathering and Transportation Eliminations Total (In millions) Revenues: Product sales: Natural gas $ 203 $ 463 $ (261) $ 405 Natural gas liquids 658 8 (8) 658 Condensate 67 — — 67 Total revenues from natural gas, natural gas liquids, and condensate 928 471 (269) 1,130 Loss on derivative activity (39) (4) — (43) Total Product sales $ 889 $ 467 $ (269) $ 1,087 Service revenues: Demand revenues $ 57 $ 234 $ — $ 291 Volume-dependent revenues 351 34 (6) 379 Total Service revenues $ 408 $ 268 $ (6) $ 670 Total Revenues $ 1,297 $ 735 $ (275) $ 1,757 Six Months Ended June 30, 2020 Gathering and Transportation Eliminations Total (In millions) Revenues: Product sales: Natural gas $ 103 $ 130 $ (113) $ 120 Natural gas liquids 315 5 (5) 315 Condensate 34 — — 34 Total revenues from natural gas, natural gas liquids, and condensate 452 135 (118) 469 Gain (loss) on derivative activity 16 (1) — 15 Total Product sales $ 468 $ 134 $ (118) $ 484 Service revenues: Demand revenues $ 73 $ 255 $ — $ 328 Volume-dependent revenues 327 28 (4) 351 Total Service revenues $ 400 $ 283 $ (4) $ 679 Total Revenues $ 868 $ 417 $ (122) $ 1,163
Schedule of Accounts Receivable	The following table summarizes the components of accounts receivable, net of allowance for doubtful accounts. June 30, 2021 December 31, 2020 (In millions) Accounts Receivable: Customers $ 301 $ 245 Contract assets (1) 31 12 Non-customers 6 6 Total Accounts Receivable (2) $ 338 $ 263 ____________________ (1) Contract assets reflected in Total Accounts Receivable include accrued minimum volume commitments. Contract assets are primarily attributable to revenues associated with estimated shortfall volumes on certain annual minimum volume commitment arrangements. Total Accounts Receivable does not include contract assets related to firm service transportation contracts with tiered rates of $11 million as of June 30, 2021 and $9 million as of December 31, 2020, which are reflected in Other Assets. (2) Total Accounts Receivable includes Accounts receivable, net of allowance for doubtful accounts and Accounts receivable—affiliated companies.	[1],[2]
Summary of Timing Recognition of Contract Liabilities	The table below summarizes the change in the contract liabilities. June 30, 2021 December 31, 2020 (In millions) Deferred revenues, beginning of period (1) $ 44 $ 48 Amounts recognized in revenues related to the beginning balance (19) (25) Net additions 20 21 Deferred revenues, end of period (1) $ 45 $ 44 ____________________ (1) Deferred revenues includes deferred revenue — affiliated companies. This amount is included in Other current liabilities and Other long-term liabilities. The table below summarizes the timing of recognition of these contract liabilities as of June 30, 2021. 2021 2022 2023 2024 2025 and After (In millions) Deferred revenues (1) $ 22 $ 7 $ 7 $ 7 $ 2 ____________________ (1) Deferred revenues includes deferred revenue — affiliated companies. This amount is included in Other current liabilities and Other long-term liabilities.	[3]
Summary of Timing Recognition of Remaining Performance Obligations	The table below summarizes the timing of recognition of the remaining performance obligations as of June 30, 2021. 2021 2022 2023 2024 2025 and After (In millions) Transportation and Storage $ 221 $ 404 $ 355 $ 265 $ 959 Gathering and Processing 60 122 121 101 213 Total remaining performance obligations $ 281 $ 526 $ 476 $ 366 $ 1,172
[1]	Contract assets reflected in Total Accounts Receivable include accrued minimum volume commitments. Contract assets are primarily attributable to revenues associated with estimated shortfall volumes on certain annual minimum volume commitment arrangements. Total Accounts Receivable does not include contract assets related to firm service transportation contracts with tiered rates of $11 million as of June 30, 2021 and $9 million as of December 31, 2020, which are reflected in Other Assets.
[2]	Total Accounts Receivable includes Accounts receivable, net of allowance for doubtful accounts and Accounts receivable—affiliated companies.
[3]	Deferred revenues includes deferred revenue — affiliated companies. This amount is included in Other current liabilities and Other long-term liabilities.

Leases (Tables)

Leases (Tables)	6 Months Ended
	Jun. 30, 2021
Leases [Abstract]
Schedule of Leasing Assets and Liabilities [Table Text Block]	The table below summarizes the operating leases included in the Condensed Consolidated Balance Sheets. Balance Sheet Location June 30, 2021 December 31, 2020 (In millions) Operating lease asset Other Assets $ 23 $ 25 Total right-of-use assets $ 23 $ 25 Operating lease liabilities Other Current Liabilities $ 4 $ 4 Operating lease liabilities Other Liabilities 22 24 Total lease liabilities $ 26 $ 28
Summary of Lease Expense	The following table presents the Partnership’s rental costs associated with field equipment and buildings. Three Months Ended June 30, Six Months Ended 2021 2020 2021 2020 (In millions) Rental Costs: Field equipment $ 2 $ 4 $ 5 $ 9 Office space 2 1 3 2 The following table presents the Partnership’s lease cost. Three Months Ended June 30, Six Months Ended 2021 2020 2021 2020 (In millions) Lease Cost: Operating lease cost $ 2 $ 1 $ 3 $ 3 Short-term lease cost 2 4 4 7 Variable lease cost — — 1 1 Total Lease Cost $ 4 $ 5 $ 8 $ 11 All lease costs were included in the gathering and processing reportable segment during the three and six months ended June 30, 2021 and 2020
Schedule of Operating Lease Obligations Expiration	Undiscounted cash flows for operating lease liabilities are as follows: Non-cancellable operating leases (In millions) Year Ending December 31, 2021 - remainder $ 3 2022 5 2023 5 2024 4 2025 3 2026 2 After 2026 6 Total 28 Less: impact of the applicable discount rate 2 Total lease liabilities $ 26

Earnings Per Limited Partner _2

Earnings Per Limited Partner Unit (Tables)	6 Months Ended
	Jun. 30, 2021
Earnings Per Share [Abstract]
Schedule Of Earnings Per Unit For Common Units	The following table illustrates the Partnership’s calculation of earnings per unit for common units. Three Months Ended June 30, Six Months Ended 2021 2020 2021 2020 (In millions, except per unit data) Net income $ 88 $ 44 $ 253 $ 149 Net income (loss) attributable to noncontrolling interest 1 — 2 (7) Series A Preferred Unit distributions 8 9 17 18 Net income available to common units $ 79 $ 35 $ 234 $ 138 Net income allocable to common units $ 79 $ 35 $ 234 $ 138 Dilutive effect of Series A Preferred Unit distributions — — 17 18 Diluted net income allocable to common units $ 79 $ 35 $ 251 $ 156 Basic weighted average number of common units outstanding (1) 438 437 438 437 Dilutive effect of Series A Preferred Units — — 41 79 Dilutive effect of performance units (2) 1 — — — Diluted weighted average number of common units outstanding 439 437 479 516 Basic and diluted earnings per unit Basic $ 0.18 $ 0.08 $ 0.53 $ 0.32 Diluted $ 0.18 $ 0.08 $ 0.52 $ 0.30 ____________________ (1) Basic weighted average number of outstanding common units includes approximately three million and two million time-based phantom units for the three months ended June 30, 2021 and 2020, respectively, and two million time-based phantom units for each of the six months ended June 30, 2021 and 2020, respectively. (2) The dilutive effect of the performance unit awards was less than $0.01 per unit during the three months ended June 30, 2020 and the six months ended June 30, 2021 and 2020.

Partners' Equity (Tables)

Partners' Equity (Tables)	6 Months Ended
	Jun. 30, 2021
Equity [Abstract]
Schedule of Equity Transactions with Limited Partner	The Partnership paid or has authorized payment of the following cash distributions to common unitholders, as applicable, during 2021 and 2020 (in millions, except for per unit amounts): Three Months Ended Record Date Payment Date Per Unit Distribution Total Cash Distribution June 30, 2021 (1) August 12, 2021 August 24, 2021 $ 0.16525 $ 72 March 31, 2021 May 13, 2021 May 25, 2021 $ 0.16525 $ 72 December 31, 2020 February 22, 2021 March 1, 2021 $ 0.16525 $ 72 September 30, 2020 November 17, 2020 November 24, 2020 $ 0.16525 $ 72 June 30, 2020 August 18, 2020 August 25, 2020 $ 0.16525 $ 72 March 31, 2020 May 19, 2020 May 27, 2020 $ 0.16525 $ 72 _____________________
Schedule of Cash Distributions to Series A Preferred Unitholders	The Partnership paid or has authorized payment of the following cash distributions to holders of the Series A Preferred Units during 2021 and 2020 (in millions, except for per unit amounts): Three Months Ended Record Date Payment Date Distribution Rate Per Unit Distribution Total Cash Distribution June 30, 2021 (1) July 30, 2021 August 13, 2021 8.7016 % $ 0.5439 $ 8 March 31, 2021 (2) April 26, 2021 May 14, 2021 8.7375 % $ 0.5873 $ 9 December 31, 2020 February 12, 2021 February 12, 2021 10.0 % $ 0.625 $ 9 September 30, 2020 November 3, 2020 November 13, 2020 10.0 % $ 0.625 $ 9 June 30, 2020 August 4, 2020 August 14, 2020 10.0 % $ 0.625 $ 9 March 31, 2020 May 5, 2020 May 15, 2020 10.0 % $ 0.625 $ 9 _____________________ (1) The Board of Directors declared a $0.5439 per Series A Preferred Unit cash distribution on July 30, 2021, to be paid on August 13, 2021, to Series A Preferred unitholders of record at the close of business on July 30, 2021. (2) The distribution rate for the three months ended March 31, 2021 reflects 10% through February 18, 2021, and the sum of the three-month LIBOR plus 8.5% for the remaining days in the period.

Investment in Equity Method A_2

Investment in Equity Method Affiliate (Tables)	6 Months Ended
	Jun. 30, 2021
Equity Method Investments and Joint Ventures [Abstract]
Schedule of Investments Detail	The following table presents the amount of Equity in earnings of equity method affiliate recognized and Distributions from equity method affiliate received. Three Months Ended June 30, Six Months Ended 2021 2020 2021 2020 (In millions) Equity in earnings of equity method affiliate $ — $ 5 $ 1 $ 11 Distributions from equity method affiliate (1) — 9 4 19 ___________________ (1) Distributions from equity method affiliate includes a zero and $5 million return on investment and a zero and $4 million return of investment for the three months ended June 30, 2021 and 2020, respectively. Distributions from equity method affiliate includes a $1 million and $11 million return on investment and a $3 million and $8 million return of investment for the six months ended June 30, 2021 and 2020, respectively. The following table includes the summarized financial information of SESH. Three Months Ended June 30, Six Months Ended 2021 2020 2021 2020 (In millions) Income Statements: Revenues $ 16 $ 28 $ 31 $ 55 Operating income 2 13 6 29 Net income (loss) (1) 10 (2) 21	[1]
[1]	Distributions from equity method affiliate includes a zero and $5 million return on investment and a zero and $4 million return of investment for the three months ended June 30, 2021 and 2020, respectively. Distributions from equity method affiliate includes a $1 million and $11 million return on investment and a $3 million and $8 million return of investment for the six months ended June 30, 2021 and 2020, respectively.

Debt (Tables)

Debt (Tables)	6 Months Ended
	Jun. 30, 2021
Debt Disclosure [Abstract]
Schedule of Debt	The following table presents the Partnership’s outstanding debt. June 30, 2021 December 31, 2020 Outstanding Principal Discount (1) Total Debt Outstanding Principal Discount (1) Total Debt (In millions) Commercial Paper $ 171 $ — $ 171 $ 250 $ — $ 250 Revolving Credit Facility — — — — — — 2019 Term Loan Agreement 800 — 800 800 — 800 2024 Notes 600 — 600 600 — 600 2027 Notes 700 (2) 698 700 (2) 698 2028 Notes 800 (4) 796 800 (5) 795 2029 Notes 547 (1) 546 547 (1) 546 2044 Notes 531 — 531 531 — 531 Total debt $ 4,149 $ (7) $ 4,142 $ 4,228 $ (8) $ 4,220 Less: Short-term debt (2) 171 250 Less: Current portion of long-term debt (3) 800 — Less: Unamortized debt expense (4) 18 19 Total long-term debt $ 3,153 $ 3,951 ____________________ (1) Unamortized discount on long-term debt is amortized over the life of the respective debt. (2) Short-term debt includes $171 million and $250 million of outstanding commercial paper as of June 30, 2021 and December 31, 2020, respectively. (3) As of June 30, 2021, Current portion of long-term debt included $800 million outstanding balance of the 2019 Term Loan Agreement.	[1],[2],[3],[4]
[1]	As of June 30, 2021 and December 31, 2020, there was an additional $2 million and $3 million, respectively, of unamortized debt expense related to the Revolving Credit Facility included in Other assets, not included above.
[2]	As of June 30, 2021, Current portion of long-term debt included $800 million outstanding balance of the 2019 Term Loan Agreement.
[3]	Short-term debt includes $171 million and $250 million of outstanding commercial paper as of June 30, 2021 and December 31, 2020, respectively.
[4]	Unamortized discount on long-term debt is amortized over the life of the respective debt.

Derivative Instruments and He_2

Derivative Instruments and Hedging Activities (Tables)	6 Months Ended
	Jun. 30, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Derivative Instruments	The following table presents the Partnership’s derivative instruments that were not designated as hedging instruments for accounting purposes. June 30, 2021 December 31, 2020 Gross Notional Volume Purchases Sales Purchases Sales Natural gas— TBtu (1) Financial fixed futures/swaps — 8 — 18 Financial basis futures/swaps — 22 — 27 Financial swaptions (2) — 4 — 7 Physical purchases/sales — — — — Crude oil (for condensate)— MBbl (3) Financial futures/swaps — 270 — 465 Financial swaptions (2) — 90 — 90 Natural gas liquids— MBbl (4) Financial futures/swaps 45 525 855 1,210 Financial options — 15 — 45 ____________________ (1) As of June 30, 2021, 98.7% of the natural gas contracts had durations of one year or less and 1.3% had durations of more than one year and less than two years. As of December 31, 2020, 95.7% of the natural gas contracts had durations of one year or less and 4.3% had durations of more than one year and less than two years. (2) The notional volume contains a combined derivative instrument consisting of a fixed price swap and a sold option, which gives the counterparties the right, but not the obligation, to increase the notional volume hedged under the fixed price swap until the option expiration date. The notional volume represents the volume prior to option exercise. (3) As of June 30, 2021, 91.7% of the crude oil (for condensate) contracts had durations of one year or less and 8.3% had durations of more than one year and less than two years. As of December 31, 2020, 100.0% of the crude oil (for condensate) contracts had durations of one year or less. (4) As of June 30, 2021, 94.9% of the natural gas liquids contracts had durations of one year or less and 5.1% had durations of more than one year and less than two years. As of December 31, 2020, 100.0% of the natural gas liquids contracts had durations of one year or less. The following table presents the Partnership’s derivative instruments that were designated as hedging instruments for accounting purposes. June 30, 2021 December 31, 2020 Gross Notional Value (In millions) Interest rate swaps $ 300 $ 300	[1],[2],[3],[4]
Schedule of Derivative Assets at Fair Value	The following table presents the fair value of the derivative instruments that are included in the Partnership’s Condensed Consolidated Balance Sheets that were not designated as hedging instruments for accounting purposes. June 30, 2021 December 31, 2020 Fair Value Instrument Balance Sheet Location Assets Liabilities Assets Liabilities (In millions) Natural gas Financial futures/swaps Other Current $ — $ 9 $ 2 $ 2 Financial swaptions Other Current — 6 1 2 Crude oil (for condensate) Financial futures/swaps Other Current — 7 1 13 Financial swaptions Other Current — 1 — — Financial swaptions Other — 1 — — Natural gas liquids Financial futures/swaps Other Current 4 10 15 3 Financial swaptions Other Current — 1 — 1 Total gross commodity derivatives (1) $ 4 $ 35 $ 19 $ 21 _____________________ (1) See Note 11 for a reconciliation of the Partnership’s commodity derivatives fair value to the Partnership’s Condensed Consolidated Balance Sheets as of June 30, 2021 and December 31, 2020. The following table presents the fair value of the derivative instruments that are included in the Partnership’s Condensed Consolidated Balance Sheets that were designated as hedging instruments for accounting purposes. June 30, 2021 December 31, 2020 Fair Value Instrument Balance Sheet Location Assets Liabilities Assets Liabilities (In millions) Interest rate swaps (1) Other Current $ — $ 3 $ — $ 6 _____________________ (1) All interest rate derivative instruments that were designated as cash flow hedges are considered Level 2 as of June 30, 2021 and December 31, 2020.
Schedule of Derivative Instruments in Statement of Financial Position, Fair Value	The following table presents the effect of derivative instruments on the Partnership’s Condensed Consolidated Statements of Income. Amounts Recognized in Income Three Months Ended June 30, Six Months Ended 2021 2020 2021 2020 (In millions) Natural gas Financial futures/swaps gains (losses) $ (11) $ (1) $ (13) $ 3 Financial swaptions losses (5) (1) (5) (2) Physical purchases/sales gains (losses) — — — 1 Crude oil (for condensate) Financial futures/swaps gains (losses) (6) (7) (12) 12 Financial swaptions gains (losses) (1) (2) (2) 2 Natural gas liquids Financial futures/swaps gains (losses) (6) 6 (11) (1) Total $ (29) $ (5) $ (43) $ 15 The following table presents the effect of derivative instruments that were designated as hedging instruments on the Partnership’s Condensed Consolidated Statements of Income. Amounts Recognized in Income Three Months Ended June 30, Six Months Ended 2021 2020 2021 2020 (In millions) Interest rate swaps losses $ (2) $ (1) $ (3) $ (1)
Schedule of Other Derivatives Not Designated as Hedging Instruments, Statements of Financial Performance and Financial Position, Location	The following table presents the components of gain (loss) on derivative activity in the Partnership’s Condensed Consolidated Statements of Income. Three Months Ended June 30, Six Months Ended 2021 2020 2021 2020 (In millions) Change in fair value of commodity derivatives $ (19) $ (12) $ (29) $ (2) Realized gains (losses) on commodity derivatives (10) 7 (14) 17 Gains (losses) on commodity derivative activity $ (29) $ (5) $ (43) $ 15
[1]	As of June 30, 2021, 91.7% of the crude oil (for condensate) contracts had durations of one year or less and 8.3% had durations of more than one year and less than two years. As of December 31, 2020, 100.0% of the crude oil (for condensate) contracts had durations of one year or less.
[2]	As of June 30, 2021, 94.9% of the natural gas liquids contracts had durations of one year or less and 5.1% had durations of more than one year and less than two years. As of December 31, 2020, 100.0% of the natural gas liquids contracts had durations of one year or less.
[3]	As of June 30, 2021, 98.7% of the natural gas contracts had durations of one year or less and 1.3% had durations of more than one year and less than two years. As of December 31, 2020, 95.7% of the natural gas contracts had durations of one year or less and 4.3% had durations of more than one year and less than two years.
[4]	The notional volume contains a combined derivative instrument consisting of a fixed price swap and a sold option, which gives the counterparties the right, but not the obligation, to increase the notional volume hedged under the fixed price swap until the option expiration date. The notional volume represents the volume prior to option exercise.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2021
Fair Value Disclosures [Abstract]
Schedule of Fair Value and Carrying Amount of Financial Instruments	The following table summarizes the fair value and carrying amount of the Partnership’s financial instruments. June 30, 2021 December 31, 2020 Carrying Amount Fair Value Carrying Amount Fair Value (In millions) Debt Revolving Credit Facility (Level 2) (1) $ — $ — $ — $ — 2019 Term Loan Agreement (Level 2) 800 800 800 800 2024 Notes (Level 2) 600 639 600 612 2027 Notes (Level 2) 698 774 698 709 2028 Notes (Level 2) 796 916 795 817 2029 Notes (Level 2) 546 599 546 544 2044 Notes (Level 2) 531 578 531 499 ____________________ (1) Borrowing capacity is effectively reduced by our borrowings outstanding under the commercial paper program. $171 million and $250 million of commercial paper was outstanding as of June 30, 2021 and December 31, 2020, respectively.	[1]
Schedule of Assets and Liabilities Measured at Fair Value on a Recurring Basis	The following tables summarize the Partnership’s other assets and liabilities that are measured at fair value on a recurring basis. June 30, 2021 Commodity Contracts Gas Imbalances (1) Assets Liabilities Assets (2) Liabilities (3) (In millions) Quoted market prices in active market for identical assets (Level 1) $ — $ 11 $ — $ — Significant other observable inputs (Level 2) 4 24 14 11 Total fair value 4 35 14 11 Netting adjustments (4) (4) — — Total $ — $ 31 $ 14 $ 11 December 31, 2020 Commodity Contracts Gas Imbalances (1) Assets Liabilities Assets (2) Liabilities (3) (In millions) Quoted market prices in active market for identical assets (Level 1) $ 2 $ 14 $ — $ — Significant other observable inputs (Level 2) 17 7 23 16 Total fair value 19 21 23 16 Netting adjustments (19) (19) — — Total $ — $ 2 $ 23 $ 16 ______________________ (1) The Partnership uses the market approach to fair value its gas imbalance assets and liabilities at individual, or where appropriate an average of, current market indices applicable to the Partnership’s operations, not to exceed net realizable value. There were no netting adjustments as of June 30, 2021 and December 31, 2020. (2) Gas imbalance assets exclude fuel reserves for under retained fuel due from shippers of $14 million and $19 million at June 30, 2021 and December 31, 2020, respectively, which fuel reserves are based on the value of natural gas at the time the imbalance was created, and which are not subject to revaluation at fair market value. (3) Gas imbalance liabilities exclude fuel reserves for over retained fuel due to shippers of $3 million and $3 million at June 30, 2021 and December 31, 2020, respectively, which fuel reserves are based on the value of natural gas at the time the imbalance was created, and which are not subject to revaluation at fair market value.	[2],[3],[4]
[1]	Borrowing capacity is effectively reduced by our borrowings outstanding under the commercial paper program. $171 million and $250 million of commercial paper was outstanding as of June 30, 2021 and December 31, 2020, respectively.
[2]	Gas imbalance assets exclude fuel reserves for under retained fuel due from shippers of $14 million and $19 million at June 30, 2021 and December 31, 2020, respectively, which fuel reserves are based on the value of natural gas at the time the imbalance was created, and which are not subject to revaluation at fair market value.
[3]	Gas imbalance liabilities exclude fuel reserves for over retained fuel due to shippers of $3 million and $3 million at June 30, 2021 and December 31, 2020, respectively, which fuel reserves are based on the value of natural gas at the time the imbalance was created, and which are not subject to revaluation at fair market value.
[4]	The Partnership uses the market approach to fair value its gas imbalance assets and liabilities at individual, or where appropriate an average of, current market indices applicable to the Partnership’s operations, not to exceed net realizable value. There were no netting adjustments as of June 30, 2021 and December 31, 2020.

Supplemental Disclosure of Ca_2

Supplemental Disclosure of Cash Flow Information (Tables)	6 Months Ended
	Jun. 30, 2021
Supplemental Cash Flow Information [Abstract]
Schedule of Cash Flow, Supplemental Disclosures	The following table provides information regarding supplemental cash flow information: Six Months Ended June 30, 2021 2020 (In millions) Supplemental Disclosure of Cash Flow Information: Cash Payments: Interest, net of capitalized interest and debt AFUDC $ 81 $ 96 Income taxes, net of refunds (1) 1 Non-cash transactions: Accounts payable related to capital expenditures 6 8 Lease liabilities related to derecognition of right-of-use assets — (5) Impact of adoption of financial instruments-credit losses accounting standard (Note 1) — (3)

Related Party Transactions (Tab

Related Party Transactions (Tables)	6 Months Ended
	Jun. 30, 2021
Related Party Transactions [Abstract]
Schedule of Revenues from Related Parties	The following table presents the amounts of revenues from affiliated companies included in the Partnership’s Condensed Consolidated Statements of Income. Three Months Ended June 30, Six Months Ended 2021 2020 2021 2020 (In millions) Gas transportation and storage service revenues — CenterPoint Energy $ 16 $ 22 $ 43 $ 59 Natural gas product sales — CenterPoint Energy 5 1 5 1 Gas transportation and storage service revenues — OGE Energy 9 10 19 19 Natural gas product sales — OGE Energy 2 — 33 5 Total revenues — affiliated companies $ 32 $ 33 $ 100 $ 84
Schedule of Natural Gas Purchased From Related Parties	The following table presents the amounts of natural gas purchased from affiliated companies included in the Partnership’s Condensed Consolidated Statements of Income. Three Months Ended June 30, Six Months Ended 2021 2020 2021 2020 (In millions) Cost of natural gas purchases — CenterPoint Energy $ — $ — $ — $ 1 Cost of natural gas purchases — OGE Energy 12 6 43 14 Total cost of natural gas purchases — affiliated companies $ 12 $ 6 $ 43 $ 15
Schedule of Amounts Charged to Partnership by Related Parties	The following table presents the amounts charged to the Partnership by affiliates for seconded employees, included primarily in Operation and maintenance and General and administrative expenses in the Partnership’s Condensed Consolidated Statements of Income. Three Months Ended June 30, Six Months Ended 2021 2020 2021 2020 (In millions) Seconded Employee Costs — OGE Energy $ 3 $ 5 $ 7 $ 8

Equity-Based Compensation (Tabl

Equity-Based Compensation (Tables)	6 Months Ended
	Jun. 30, 2021
Share-based Payment Arrangement [Abstract]
Disclosure of Share-based Compensation Arrangements by Share-based Payment Award	The following table summarizes the Partnership’s equity-based compensation expense related to performance units and phantom units for the Partnership’s employees and independent directors. Three Months Ended June 30, Six Months Ended 2021 2020 2021 2020 (In millions) Performance units $ 2 $ 2 $ 4 $ 4 Phantom units 2 1 4 3 Total compensation expense $ 4 $ 3 $ 8 $ 7 The following table presents the assumptions related to the performance units granted in 2021. 2021 Number of units granted 1,453,897 Fair value of units granted $ 10.26 Expected distribution yield 12.90 % Expected price volatility 100.00 % Risk-free interest rate 0.27 % Expected life of units (in years) 3 The following table presents the number of phantom units granted and the grant date fair value related to the phantom units granted in 2021. 2021 Phantom Units granted 1,371,001 Fair value of phantom units granted $5.41 - $6.87
Schedule of Share-based Compensation, Activity	A summary of the activity for the Partnership’s performance units and phantom units applicable to the Partnership’s employees at June 30, 2021 and changes during 2021 are shown in the following table. Performance Units Phantom Units Number Weighted Average Grant-Date Fair Value, Per Unit Number Weighted Average Grant-Date Fair Value, Per Unit (In millions, except unit data) Units outstanding at December 31, 2020 1,765,508 $ 13.10 1,790,845 $ 10.29 Granted (1) 1,453,897 10.26 1,371,001 6.86 Vested (2) (389,817) 17.70 (469,488) 13.07 Forfeited (45,945) 9.94 (119,851) 8.51 Units outstanding at June 30, 2021 2,783,643 $ 11.02 2,572,507 $ 8.03 Aggregate intrinsic value of units outstanding at June 30, 2021 $ 25 $ 23 _____________________ (1) Performance units represents the target number of performance units granted. The actual number of performance units earned, if any, is dependent upon performance and may range from 0% to 200% of the target. (2) Performance units vested as of June 30, 2021 include 389,817 units from the 2018 annual grant, which were approved by the Board of Directors in 2018 and, based on the level of achievement of a performance goal established by the Board of Directors over the performance period of January 1, 2018 through December 31, 2020, no performance units vested.	[1],[2]
Schedule of Unrecognized Compensation Cost, Nonvested Awards	The following table summarizes the Partnership’s unrecognized compensation cost for its non-vested performance units and phantom units, and the weighted-average periods over which the compensation cost is expected to be recognized. June 30, 2021 Unrecognized Compensation Cost Weighted Average Period for Recognition Performance Units $ 19 2.00 Phantom Units 12 1.84 Total $ 31
[1]	Performance units represents the target number of performance units granted. The actual number of performance units earned, if any, is dependent upon performance and may range from 0% to 200% of the target.
[2]	Performance units vested as of June 30, 2021 include 389,817 units from the 2018 annual grant, which were approved by the Board of Directors in 2018 and, based on the level of achievement of a performance goal established by the Board of Directors over the performance period of January 1, 2018 through December 31, 2020, no performance units vested.

Reportable Segments (Tables)

Reportable Segments (Tables)	6 Months Ended
	Jun. 30, 2021
Segment Reporting [Abstract]
Schedule of Financial Data for Business Segments and Services	Financial data for reportable segments are as follows: Three Months Ended June 30, 2021 Gathering and Transportation (1) and Storage Eliminations Total (In millions) Product sales $ 461 $ 135 $ (136) $ 460 Service revenues 212 118 (3) 327 Total Revenues 673 253 (139) 787 Cost of natural gas and natural gas liquids (excluding depreciation and amortization shown separately) 437 128 (139) 426 Operation and maintenance, General and administrative 73 44 (1) 116 Depreciation and amortization 74 29 — 103 Taxes other than income tax 11 7 — 18 Operating income $ 78 $ 45 $ 1 $ 124 Total Assets $ 10,824 $ 5,917 $ (4,982) $ 11,759 Capital expenditures (excluding equity AFUDC) $ 20 $ 51 $ — $ 71 Three Months Ended June 30, 2020 Gathering and Transportation (1) and Storage Eliminations Total (In millions) Product sales $ 193 $ 59 $ (56) $ 196 Service revenues 198 124 (3) 319 Total Revenues 391 183 (59) 515 Cost of natural gas and natural gas liquids (excluding depreciation and amortization shown separately) 176 59 (58) 177 Operation and maintenance, General and administrative 92 45 (1) 136 Depreciation and amortization 74 31 — 105 Taxes other than income tax 11 6 — 17 Operating income $ 38 $ 42 $ — $ 80 Total assets as of December 31, 2020 $ 10,830 $ 5,729 $ (4,830) $ 11,729 Capital expenditures (excluding equity AFUDC) $ 24 $ 24 $ — $ 48 Six Months Ended June 30, 2021 Gathering and Transportation (1) and Storage Eliminations Total (In millions) Product sales $ 889 $ 467 $ (269) $ 1,087 Service revenues 408 268 (6) 670 Total Revenues 1,297 735 (275) 1,757 Cost of natural gas and natural gas liquids (excluding depreciation and amortization shown separately) 835 385 (275) 945 Operation and maintenance, General and administrative 152 86 (1) 237 Depreciation and amortization 148 61 — 209 Taxes other than income tax 22 14 — 36 Operating income $ 140 $ 189 $ 1 $ 330 Total Assets $ 10,824 $ 5,917 $ (4,982) $ 11,759 Capital expenditures (excluding equity AFUDC) $ 41 $ 110 $ — $ 151 Six Months Ended June 30, 2020 Gathering and Transportation (1) and Storage Eliminations Total (In millions) Product sales $ 468 $ 134 $ (118) $ 484 Service revenues 400 283 (4) 679 Total Revenues 868 417 (122) 1,163 Cost of natural gas and natural gas liquids (excluding depreciation and amortization shown separately) 387 137 (121) 403 Operation and maintenance, General and administrative 173 90 (1) 262 Depreciation and amortization 148 61 — 209 Impairments of property, plant and equipment and goodwill 28 — — 28 Taxes other than income tax 22 13 — 35 Operating income $ 110 $ 116 $ — $ 226 Total assets as of December 31, 2020 $ 10,830 $ 5,729 $ (4,830) $ 11,729 Capital expenditures (excluding equity AFUDC) $ 58 $ 44 $ — $ 102 _____________________ (1) See Note 8 for discussion regarding ownership interests in SESH and related equity earnings included in the transportation and storage segment for the three and six months ended June 30, 2021 and 2020.	[1]
[1]	See Note 8 for discussion regarding ownership interests in SESH and related equity earnings included in the transportation and storage segment for the three and six months ended June 30, 2021 and 2020.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Narrative (Details) $ in Millions	Feb. 16, 2021USD ($)shares	Apr. 08, 2020USD ($)	Apr. 01, 2020USD ($)	Jun. 30, 2021USD ($)board_membershares	Jun. 30, 2020USD ($)	Jun. 30, 2021USD ($)segmentboard_membershares	Jun. 30, 2020USD ($)	Mar. 31, 2021USD ($)	Dec. 31, 2020USD ($)	Mar. 31, 2020USD ($)	Dec. 31, 2019USD ($)
Significant Accounting Policies [Line Items]
Number of reportable segments | segment						2
Number of representatives designated by each of CenterPoint Energy and OGE Energy | board_member				2		2
Number of independent board members | board_member				3		3
Percentage vote by all unitholders (at least 75%)						75.00%
Merger Termination Fee	$ 97.5
Sale of interest			$ 19
Loss on retirement						$ 0	$ (17)
Partners' Capital, Including Portion Attributable to Noncontrolling Interest				$ 7,193	$ 7,317	7,193	7,317	$ 7,181	$ 7,095	$ 7,352	$ 7,409
Accounts receivable				3		3			1
Other assets				2		2			3
Total Allowance for doubtful accounts				5		5			4
Inventory adjustments				0	1	1	7
Allowance for Funds Used During Construction, Capitalized Interest and Combined Debt and Equity				$ 6	1	$ 7	1
Gathering and Processing
Significant Accounting Policies [Line Items]
Loss on retirement		$ 20
Partnership Interest
Significant Accounting Policies [Line Items]
Payments to Acquire Businesses, Gross	$ 10
Cumulative Effect, Period of Adoption, Adjustment
Significant Accounting Policies [Line Items]
Partners' Capital, Including Portion Attributable to Noncontrolling Interest											(3)
Common Unit [Member]
Significant Accounting Policies [Line Items]
Merger Agreement, Right to Receive Number of Common Units Per Share | shares	0.8595
Series A Preferred Units [Member]
Significant Accounting Policies [Line Items]
Merger Agreement, Right to Receive Number of Common Units Per Share | shares	0.0265
Atoka
Significant Accounting Policies [Line Items]
Ownership interest (as a percentage)						50.00%
ESCP
Significant Accounting Policies [Line Items]
Ownership interest (as a percentage)						60.00%
OGE Energy | Partners' Capital
Significant Accounting Policies [Line Items]
Limited partner ownership interest percentage						25.50%
CenterPoint | Partners' Capital
Significant Accounting Policies [Line Items]
Limited partner ownership interest percentage						53.70%
CenterPoint and OGE Energy | Partners' Capital
Significant Accounting Policies [Line Items]
Limited partner ownership interest percentage						79.00%
OGE Energy | Partners' Capital | Common Unit [Member]
Significant Accounting Policies [Line Items]
Units outstanding | shares				110,982,805		110,982,805
CenterPoint | Partners' Capital | Series A 10% Fixed to Floating Non Cumulative Redeemable Perpetual Preferred Units
Significant Accounting Policies [Line Items]
Series A preferred units held by CenterPoint Energy | shares				14,520,000		14,520,000
CenterPoint | Partners' Capital | Common Unit [Member]
Significant Accounting Policies [Line Items]
Units outstanding | shares				233,856,623		233,856,623
Partners' Capital | Common Unit [Member]
Significant Accounting Policies [Line Items]
Partners' Capital, Including Portion Attributable to Noncontrolling Interest				$ 6,809	$ 6,937	$ 6,809	$ 6,937	$ 6,798	$ 6,713	$ 6,972	7,013
Partners' Capital | Common Unit [Member] | Cumulative Effect, Period of Adoption, Adjustment
Significant Accounting Policies [Line Items]
Partners' Capital, Including Portion Attributable to Noncontrolling Interest				$ 0		$ 0					$ (3)
Partners' Capital | OGE Energy
Significant Accounting Policies [Line Items]
Percentage share of management rights				50.00%		50.00%
Percentage share of incentive distribution rights				60.00%		60.00%
Partners' Capital | CenterPoint
Significant Accounting Policies [Line Items]
Percentage share of management rights				50.00%		50.00%
Percentage share of incentive distribution rights				40.00%		40.00%

Revenue - Disaggregation of Rev

Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021		Jun. 30, 2020
Disaggregation of Revenue [Line Items]
Total revenues from natural gas, natural gas liquids, and condensate	$ 489	$ 201	$ 1,130		$ 469
Gain (loss) on derivative activity	(29)	(5)	(43)		15
Total Revenues	787	515	1,757		1,163
Natural gas
Disaggregation of Revenue [Line Items]
Total revenues from natural gas, natural gas liquids, and condensate	93	51	405		120
Natural gas liquids
Disaggregation of Revenue [Line Items]
Total revenues from natural gas, natural gas liquids, and condensate	361	143	658		315
Condensate Natural Gas
Disaggregation of Revenue [Line Items]
Total revenues from natural gas, natural gas liquids, and condensate	35	7	67		34
Product
Disaggregation of Revenue [Line Items]
Total Revenues	460	196	1,087		484
Demand Service Revenue
Disaggregation of Revenue [Line Items]
Total Revenues	138	147	291		328
Volume Dependant Service Revenue
Disaggregation of Revenue [Line Items]
Total Revenues	189	172	379		351
Natural Gas, Gathering, Transportation, Marketing and Processing
Disaggregation of Revenue [Line Items]
Total Revenues	327	319	670		679
Operating Segments | Gathering and Processing
Disaggregation of Revenue [Line Items]
Total revenues from natural gas, natural gas liquids, and condensate	487	197	928		452
Gain (loss) on derivative activity	(26)	(4)	(39)		16
Total Revenues	673	391	1,297		868
Operating Segments | Gathering and Processing | Natural gas
Disaggregation of Revenue [Line Items]
Total revenues from natural gas, natural gas liquids, and condensate	91	47	203		103
Operating Segments | Gathering and Processing | Natural gas liquids
Disaggregation of Revenue [Line Items]
Total revenues from natural gas, natural gas liquids, and condensate	361	143	658		315
Operating Segments | Gathering and Processing | Condensate Natural Gas
Disaggregation of Revenue [Line Items]
Total revenues from natural gas, natural gas liquids, and condensate	35	7	67		34
Operating Segments | Gathering and Processing | Product
Disaggregation of Revenue [Line Items]
Total Revenues	461	193	889		468
Operating Segments | Gathering and Processing | Demand Service Revenue
Disaggregation of Revenue [Line Items]
Total Revenues	31	34	57		73
Operating Segments | Gathering and Processing | Volume Dependant Service Revenue
Disaggregation of Revenue [Line Items]
Total Revenues	181	164	351		327
Operating Segments | Gathering and Processing | Natural Gas, Gathering, Transportation, Marketing and Processing
Disaggregation of Revenue [Line Items]
Total Revenues	212	198	408		400
Operating Segments | Transportation and Storage
Disaggregation of Revenue [Line Items]
Total revenues from natural gas, natural gas liquids, and condensate	138	60	471		135
Gain (loss) on derivative activity	(3)	(1)	(4)		(1)
Total Revenues	253	183	735	[1]	417	[1]
Operating Segments | Transportation and Storage | Natural gas
Disaggregation of Revenue [Line Items]
Total revenues from natural gas, natural gas liquids, and condensate	133	57	463		130
Operating Segments | Transportation and Storage | Natural gas liquids
Disaggregation of Revenue [Line Items]
Total revenues from natural gas, natural gas liquids, and condensate	5	3	8		5
Operating Segments | Transportation and Storage | Condensate Natural Gas
Disaggregation of Revenue [Line Items]
Total revenues from natural gas, natural gas liquids, and condensate	0	0	0		0
Operating Segments | Transportation and Storage | Product
Disaggregation of Revenue [Line Items]
Total Revenues	135	59	467	[1]	134	[1]
Operating Segments | Transportation and Storage | Demand Service Revenue
Disaggregation of Revenue [Line Items]
Total Revenues	107	113	234		255
Operating Segments | Transportation and Storage | Volume Dependant Service Revenue
Disaggregation of Revenue [Line Items]
Total Revenues	11	11	34		28
Operating Segments | Transportation and Storage | Natural Gas, Gathering, Transportation, Marketing and Processing
Disaggregation of Revenue [Line Items]
Total Revenues	118	124	268	[1]	283	[1]
Eliminations
Disaggregation of Revenue [Line Items]
Total revenues from natural gas, natural gas liquids, and condensate	(136)	(56)	(269)		(118)
Gain (loss) on derivative activity	0	0	0		0
Total Revenues	(139)	(59)	(275)		(122)
Eliminations | Natural gas
Disaggregation of Revenue [Line Items]
Total revenues from natural gas, natural gas liquids, and condensate	(131)	(53)	(261)		(113)
Eliminations | Natural gas liquids
Disaggregation of Revenue [Line Items]
Total revenues from natural gas, natural gas liquids, and condensate	(5)	(3)	(8)		(5)
Eliminations | Condensate Natural Gas
Disaggregation of Revenue [Line Items]
Total revenues from natural gas, natural gas liquids, and condensate	0	0	0		0
Eliminations | Product
Disaggregation of Revenue [Line Items]
Total Revenues	(136)	(56)	(269)		(118)
Eliminations | Demand Service Revenue
Disaggregation of Revenue [Line Items]
Total Revenues	0	0	0		0
Eliminations | Volume Dependant Service Revenue
Disaggregation of Revenue [Line Items]
Total Revenues	(3)	(3)	(6)		(4)
Eliminations | Natural Gas, Gathering, Transportation, Marketing and Processing
Disaggregation of Revenue [Line Items]
Total Revenues	$ (3)	$ (3)	$ (6)		$ (4)
[1]	See Note 8 for discussion regarding ownership interests in SESH and related equity earnings included in the transportation and storage segment for the three and six months ended June 30, 2021 and 2020.

Revenue - Narrative (Details)

Revenue - Narrative (Details) $ in Millions	6 Months Ended
	Jun. 30, 2020USD ($)
Revenue from Contract with Customer [Abstract]
Revenue recognized related to rate case settlement	$ 17
Regulatory Liabilities, Refund to Customers	$ 21

Revenue - Accounts Receivable (

Revenue - Accounts Receivable (Details) - USD ($) $ in Millions		Jun. 30, 2021	Dec. 31, 2020
Disaggregation of Revenue [Line Items]
Customers		$ 301	$ 245
Contract assets	[1]	31	12
Non-customers		6	6
Total Accounts Receivable	[2]	338	263
Firm Service Transportation [Member]
Disaggregation of Revenue [Line Items]
Contract assets		$ 11	$ 9
[1]	Contract assets reflected in Total Accounts Receivable include accrued minimum volume commitments. Contract assets are primarily attributable to revenues associated with estimated shortfall volumes on certain annual minimum volume commitment arrangements. Total Accounts Receivable does not include contract assets related to firm service transportation contracts with tiered rates of $11 million as of June 30, 2021 and $9 million as of December 31, 2020, which are reflected in Other Assets.
[2]	Total Accounts Receivable includes Accounts receivable, net of allowance for doubtful accounts and Accounts receivable—affiliated companies.

Revenue - Summary of Changes in

Revenue - Summary of Changes in Contract Liabilities (Details) - USD ($) $ in Millions		6 Months Ended	12 Months Ended
		Jun. 30, 2021	Dec. 31, 2020	Dec. 31, 2019
Revenue from Contract with Customer [Abstract]
Contract with Customer, Liability	[1]	$ 45	$ 44	$ 48
Amounts recognized in revenues related to the beginning balance		(19)	(25)
Net additions		$ 20	$ 21
[1]	Deferred revenues includes deferred revenue — affiliated companies. This amount is included in Other current liabilities and Other long-term liabilities.

Revenue - Summary of Recognitio

Revenue - Summary of Recognition Contract Liabilities (Details) $ in Millions	6 Months Ended
	Jun. 30, 2021USD ($)	[1]
Revenue from Contract with Customer [Abstract]
2021	$ 22
2022	7
2023	7
2024	7
2025 and After	$ 2
[1]	Deferred revenues includes deferred revenue — affiliated companies. This amount is included in Other current liabilities and Other long-term liabilities.

Revenue - Summary of Recognit_2

Revenue - Summary of Recognition of Remaining Performance Obligations (Details) $ in Millions	Jun. 30, 2021USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-07-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	6 months
Total remaining performance obligations	$ 281
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-07-01 | Transportation and Storage
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	6 months
Total remaining performance obligations	$ 221
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-07-01 | Gathering and Processing
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	6 months
Total remaining performance obligations	$ 60
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Total remaining performance obligations	$ 526
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01 | Transportation and Storage
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Total remaining performance obligations	$ 404
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01 | Gathering and Processing
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Total remaining performance obligations	$ 122
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Total remaining performance obligations	$ 476
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01 | Transportation and Storage
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Total remaining performance obligations	$ 355
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01 | Gathering and Processing
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Total remaining performance obligations	$ 121
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Total remaining performance obligations	$ 366
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01 | Transportation and Storage
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Total remaining performance obligations	$ 265
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01 | Gathering and Processing
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Total remaining performance obligations	$ 101
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	22 years 5 months
Total remaining performance obligations	$ 1,172
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01 | Transportation and Storage
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	22 years 5 months
Total remaining performance obligations	$ 959
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01 | Gathering and Processing
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	4 years 2 months
Total remaining performance obligations	$ 213

Leases - Schedule of Leasing As

Leases - Schedule of Leasing Assets and Liabilities (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Lessee, Lease, Description [Line Items]
Operating lease asset	$ 23	$ 25
Total lease liabilities	26	28
Other Current Liabilities
Lessee, Lease, Description [Line Items]
Operating Lease, Liability, Current	4	4
Other Liabilities
Lessee, Lease, Description [Line Items]
Operating Lease, Liability, Noncurrent	22	24
Other Assets [Member]
Lessee, Lease, Description [Line Items]
Operating lease asset	$ 23	$ 25

Leases - Summary of Lease Expen

Leases - Summary of Lease Expense (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Lessee, Lease, Description [Line Items]
Weighted average lease term (in years)	6 years 3 months 18 days		6 years 3 months 18 days
Weighted average discount rate (as a percentage)	5.49%		5.49%
Gathering and Processing
Lessee, Lease, Description [Line Items]
Rental costs	$ 4	$ 5	$ 8	$ 11
Operating lease cost	2	1	3	3
Short-term lease cost	2	4	4	7
Variable Lease, Cost	0	0	1	1
Total Lease Cost	4	5	8	11
Field equipment
Lessee, Lease, Description [Line Items]
Rental costs	2	4	5	9
Total Lease Cost	2	4	5	9
Buildings
Lessee, Lease, Description [Line Items]
Rental costs	2	1	3	2
Total Lease Cost	$ 2	$ 1	$ 3	$ 2

Leases - Schedule of Operating

Leases - Schedule of Operating Lease Obligations Expiration (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Leases [Abstract]
2021 - remainder	$ 3
2022	5
2023	5
2024	4
2025	3
2026	2
After 2026	6
Total	28
Less: impact of the applicable discount rate	2
Total lease liabilities	$ 26	$ 28

Earnings Per Limited Partner _3

Earnings Per Limited Partner Unit (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income		$ 88	$ 44	$ 253	$ 149
Net income (loss) attributable to noncontrolling interest		1	0	2	(7)
Series A Preferred Unit distributions		8	9	17	18
Net Income Attributable to Common Units (Note 5)		$ 79	$ 35	$ 234	$ 138
Diluted earnings (loss) per unit
Earnings Per Share, Diluted, Undistributed		$ 0.01	$ 0.01	$ 0.01	$ 0.01
Phantom units
Basic weighted average number of outstanding
Basic weighted average number of outstanding		3,000,000	2,000,000	2,000,000	2,000,000
Common Unit [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net Income Attributable to Common Units (Note 5)		$ 79	$ 35	$ 234	$ 138
Dilutive effect of Series A Preferred Unit distributions		0	0	17	18
Diluted net income		$ 79	$ 35	$ 251	$ 156
Basic weighted average number of outstanding
Basic weighted average number of outstanding	[1]	438	437	438	437
Dilutive effect of Series A Preferred Units (in units)		0	0	41	79
Dilutive effect of performance units (in units)	[2]	1	0	0	0
Diluted weighted average number of outstanding units		439	437	479	516
Basic and diluted earnings per unit
Basic and diluted earnings per unit		$ 0.18	$ 0.08	$ 0.53	$ 0.32
Diluted earnings (loss) per unit
Diluted earnings per unit		$ 0.18	$ 0.08	$ 0.52	$ 0.30
[1]	Basic weighted average number of outstanding common units includes approximately three million and two million time-based phantom units for the three months ended June 30, 2021 and 2020, respectively, and two million time-based phantom units for each of the six months ended June 30, 2021 and 2020, respectively.
[2]	The dilutive effect of the performance unit awards was less than $0.01 per unit during the three months ended June 30, 2020 and the six months ended June 30, 2021 and 2020.

Partners' Equity - Schedule of

Partners' Equity - Schedule of Cash Distributions (Details) - USD ($) $ / shares in Units, $ in Millions

Aug. 24, 2021

Aug. 13, 2021

Aug. 12, 2021

Jul. 30, 2021

May 25, 2021

May 14, 2021

[1]

May 13, 2021

Apr. 26, 2021

[1]

Mar. 01, 2021

Feb. 22, 2021

Feb. 12, 2021

Nov. 24, 2020

Nov. 17, 2020

Nov. 13, 2020

Nov. 03, 2020

Aug. 25, 2020

Aug. 18, 2020

Aug. 14, 2020

Aug. 04, 2020

May 27, 2020

May 19, 2020

May 15, 2020

May 05, 2020

Feb. 18, 2016

Mar. 31, 2021

[1]

Jun. 30, 2021

[2]

Dec. 31, 2020

Sep. 30, 2020

Jun. 30, 2020

Mar. 31, 2020

Distribution Made to Limited Partner [Line Items]

Record Date

May 13, 2021

Feb. 22, 2021

Nov. 17, 2020

Aug. 18, 2020

May 19, 2020

Payment Date

May 25, 2021

Mar. 1, 2021

Nov. 24, 2020

Aug. 25, 2020

May 27, 2020

Series A 10% Fixed to Floating Non Cumulative Redeemable Perpetual Preferred Units

Distribution Made to Limited Partner [Line Items]

Annual percentage rate

10.00%

8.7375%

8.7016%

0.10%

0.10%

0.10%

0.10%

Series A 10% Fixed to Floating Non Cumulative Redeemable Perpetual Preferred Units | Preferred Units

Distribution Made to Limited Partner [Line Items]

Record Date

Apr. 26, 2021

Feb. 12, 2021

Nov. 3, 2020

Aug. 4, 2020

May 5, 2020

Payment Date

May 14, 2021

Feb. 12, 2021

Nov. 13, 2020

Aug. 14, 2020

May 15, 2020

Cash Distribution

Distribution Made to Limited Partner [Line Items]

Cash distribution (in dollars per unit)

$ 0.16525

$ 0.16525

$ 0.16525

$ 0.16525

$ 0.16525

Cash distribution made to unitholders

$ 72

$ 72

$ 72

$ 72

$ 72

Cash Distribution | Series A 10% Fixed to Floating Non Cumulative Redeemable Perpetual Preferred Units | Preferred Units

Distribution Made to Limited Partner [Line Items]

Cash distribution (in dollars per unit)

$ 0.5873

$ 0.625

$ 0.625

$ 0.625

$ 0.625

Cash distribution made to unitholders

$ 9

$ 9

$ 9

$ 9

$ 9

Forecast | Subsequent Event

Distribution Made to Limited Partner [Line Items]

Record Date

[3]

Aug. 12, 2021

Payment Date

[3]

Aug. 24, 2021

Forecast | Subsequent Event | Series A 10% Fixed to Floating Non Cumulative Redeemable Perpetual Preferred Units | Preferred Units

Distribution Made to Limited Partner [Line Items]

Record Date

[2]

Jul. 30, 2021

Payment Date

[2]

Aug. 13, 2021

Forecast | Subsequent Event | Cash Distribution

Distribution Made to Limited Partner [Line Items]

Cash distribution declared (in dollars per unit)

[3]

$ 0.16525

Cash distribution declared to unitholders

[3]

$ 72

Forecast | Subsequent Event | Cash Distribution | Series A 10% Fixed to Floating Non Cumulative Redeemable Perpetual Preferred Units | Preferred Units

Distribution Made to Limited Partner [Line Items]

Cash distribution declared (in dollars per unit)

[2]

$ 0.5439

Cash distribution declared to unitholders

[2]

$ 8

[1]

The distribution rate for the three months ended March 31, 2021 reflects 10% through February 18, 2021, and the sum of the three-month LIBOR plus 8.5% for the remaining days in the period.

[2]

The Board of Directors declared a $0.5439 per Series A Preferred Unit cash distribution on July 30, 2021, to be paid on August 13, 2021, to Series A Preferred unitholders of record at the close of business on July 30, 2021.

[3]

The Board of Directors declared a $0.16525 per common unit cash distribution on July 30, 2021, to be paid on August 24, 2021 to common unitholders of record at the close of business on August 12, 2021.

Partners' Equity - Narrative (D

Partners' Equity - Narrative (Details) - $ / shares	Feb. 18, 2016	Mar. 31, 2021	[1]	Jun. 30, 2021	[2]	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021
Distribution Made to Limited Partner [Line Items]
Limited partners' capital account, required quarterly distribution period										60 days
Series A 10% Fixed to Floating Non Cumulative Redeemable Perpetual Preferred Units
Distribution Made to Limited Partner [Line Items]
Annual percentage rate	10.00%	8.7375%		8.7016%		0.10%	0.10%	0.10%	0.10%
Liquidation preference (in dollars per share)	$ 25
Duration of cash distributions	5 years
Preferred units liquidation spread										8.50%
[1]	The distribution rate for the three months ended March 31, 2021 reflects 10% through February 18, 2021, and the sum of the three-month LIBOR plus 8.5% for the remaining days in the period.
[2]	The Board of Directors declared a $0.5439 per Series A Preferred Unit cash distribution on July 30, 2021, to be paid on August 13, 2021, to Series A Preferred unitholders of record at the close of business on July 30, 2021.

Impairment of Long-Lived Assets

Impairment of Long-Lived Assets (Details) - Atoka - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Impaired Long-Lived Assets Held and Used [Line Items]
Ownership interest (as a percentage)	50.00%
Gathering and Processing
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of long-lived assets		$ 16

Impairment of Goodwill (Details

Impairment of Goodwill (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Dec. 31, 2017	Jun. 30, 2020	Jun. 30, 2021	Dec. 31, 2020
Goodwill [Line Items]
Goodwill			$ 0	$ 0
Gathering and Processing
Goodwill [Line Items]
Goodwill acquired	$ 12
Goodwill impairment		$ (12)

Investment in Equity Method A_3

Investment in Equity Method Affiliate - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Schedule of Equity Method Investments [Line Items]
Amount billed associated with service agreements	$ 787	$ 515	$ 1,757	$ 1,163
SESH
Schedule of Equity Method Investments [Line Items]
Percentage of distributions through limited partner interest			50.00%
SESH | Enbridge, Inc. [Member]
Schedule of Equity Method Investments [Line Items]
Ownership percentage	50.00%		50.00%
SESH | Enable Midstream Partners, LP [Member]
Schedule of Equity Method Investments [Line Items]
Ownership percentage	50.00%		50.00%
SESH | Equity Method Investee | Shared Operations Service Agreements
Schedule of Equity Method Investments [Line Items]
Amount billed associated with service agreements	$ 3	$ 2	$ 5	$ 8

Investment in Equity Method A_4

Investment in Equity Method Affiliate - Schedule of Investments (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Equity Method Affiliates Reported Amounts:
Return on investment in equity method affiliate				$ 1	$ 11
Return of investment in equity method affiliate				3	8
Operating income		$ 124	$ 80	330	226
Net Income (Loss)		88	44	253	149
SESH
Equity Method Affiliates Reported Amounts:
Equity in earnings of equity method affiliate		0	5	1	11
Distributions from equity method affiliate (1)	[1]	0	9	4	19
Return on investment in equity method affiliate		0	5	1	11
Return of investment in equity method affiliate		0	4	3	8
Revenues		16	28	31	55
Operating income		2	13	6	29
Net Income (Loss)		$ (1)	$ 10	$ (2)	$ 21
[1]	Distributions from equity method affiliate includes a zero and $5 million return on investment and a zero and $4 million return of investment for the three months ended June 30, 2021 and 2020, respectively. Distributions from equity method affiliate includes a $1 million and $11 million return on investment and a $3 million and $8 million return of investment for the six months ended June 30, 2021 and 2020, respectively.

Debt - Schedule of Outstanding

Debt - Schedule of Outstanding Debt (Details) - USD ($) $ in Millions		Jun. 30, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Short-term debt		$ 171	$ 250
Outstanding Principal		4,149	4,228
Discount	[1]	(7)	(8)
Total Debt		4,142	4,220
Less: Unamortized debt expense	[2]	(18)	(19)
Total long-term debt		3,153	3,951
2019 Term Loan Agreement | 2019 Term Loan Agreement
Debt Instrument [Line Items]
Outstanding Principal		800	800
Discount	[1]	0	0
Total Debt		800	800
Senior Notes | 2024 Notes
Debt Instrument [Line Items]
Outstanding Principal		600	600
Discount	[1]	0	0
Total Debt		600	600
Senior Notes | 2027 Notes
Debt Instrument [Line Items]
Outstanding Principal		700	700
Discount	[1]	(2)	(2)
Total Debt		698	698
Senior Notes | 2028 Notes
Debt Instrument [Line Items]
Outstanding Principal		800	800
Discount	[1]	(4)	(5)
Total Debt		796	795
Senior Notes | 2029 Notes
Debt Instrument [Line Items]
Outstanding Principal		547	547
Discount	[1]	(1)	(1)
Total Debt		546	546
Senior Notes | 2044 Notes
Debt Instrument [Line Items]
Outstanding Principal		531	531
Discount	[1]	0	0
Total Debt		531	531
Senior Notes | Senior notes due in 2020
Debt Instrument [Line Items]
Less: Current portion of long-term debt	[3]	800	0
Revolving Credit Facility
Debt Instrument [Line Items]
Outstanding Principal		0	0
Discount	[1]	0	0
Total Debt		0	0
Unamortized debt expense related to Revolving Credit Facility		2	3
Commercial Paper
Debt Instrument [Line Items]
Short-term debt	[4]	171	250
Discount	[1]	$ 0	$ 0
[1]	Unamortized discount on long-term debt is amortized over the life of the respective debt.
[2]	As of June 30, 2021 and December 31, 2020, there was an additional $2 million and $3 million, respectively, of unamortized debt expense related to the Revolving Credit Facility included in Other assets, not included above.
[3]	As of June 30, 2021, Current portion of long-term debt included $800 million outstanding balance of the 2019 Term Loan Agreement.
[4]	Short-term debt includes $171 million and $250 million of outstanding commercial paper as of June 30, 2021 and December 31, 2020, respectively.

Debt - Narrative (Details)

Debt - Narrative (Details)		Jan. 29, 2019USD ($)	Apr. 06, 2018USD ($)	Jun. 30, 2021USD ($)	Jun. 30, 2020USD ($)	Dec. 31, 2020USD ($)
Debt Instrument [Line Items]
Commercial paper, authorized				$ 1,400,000,000
Commercial paper				$ 171,000,000		$ 250,000,000
Debt Instrument, Repurchased Face Amount					$ 22,000,000
Debt Instrument, Repurchase Amount					17,000,000
Gain on extinguishment of debt					$ 5,000,000
2019 Term Loan Agreement
Debt Instrument [Line Items]
Weighted average interest rate percentage				2.07%
Number of times option maybe exercised to extend term of Term Loan Facility		2
Debt Instrument, Term of Extension Period		1 year
Debt Instrument, Principle Advance				$ 800,000,000
LIBOR | 2019 Term Loan Agreement
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage				1.25%
Minimum | Eurodollar | 2019 Term Loan Agreement
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		0.75%
Minimum | Base Rate | 2019 Term Loan Agreement
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		0.00%
Maximum | Eurodollar | 2019 Term Loan Agreement
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		1.50%
Maximum | Base Rate | 2019 Term Loan Agreement
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		0.50%
Senior Notes | Senior Notes including 2024 Notes, 2027 Notes, 2028 Notes, 2029 Notes and 2044 Notes
Debt Instrument [Line Items]
Debt Instrument, Unamortized discount				$ 7,000,000
Debt Instrument, Debt Issuance Costs, Net				$ 18,000,000
Senior Notes | 2024 Notes
Debt Instrument [Line Items]
Debt Instrument, Interest Rate During Period				4.01%
Senior Notes | 2027 Notes
Debt Instrument [Line Items]
Debt Instrument, Interest Rate During Period				4.56%
Senior Notes | 2028 Notes
Debt Instrument [Line Items]
Debt Instrument, Interest Rate During Period				5.19%
Senior Notes | 2029 Notes
Debt Instrument [Line Items]
Debt Instrument, Interest Rate During Period				4.30%
Senior Notes | 2044 Notes
Debt Instrument [Line Items]
Debt Instrument, Interest Rate During Period				5.08%
Revolving Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity			$ 1,750,000,000
Duration of term loan facility (in years)			5 years
Increase in maximum borrowing capacity			$ 875,000,000
Number of times option maybe exercised to extend term of Term Loan Facility			2
Debt Instrument, Term of Extension Period			1 year
Letters of credit principal advances				$ 0
Letters of credit outstanding amount				3,000,000
Remaining borrowing capacity				$ 1,200,000,000
Commitment fee percentage				0.20%
Revolving Credit Facility | LIBOR
Debt Instrument [Line Items]
Applicable margin percentage				1.50%
Commercial Paper
Debt Instrument [Line Items]
Commercial paper	[1]			$ 171,000,000		$ 250,000,000
Weighted average interest rate percentage				0.42%
[1]	Short-term debt includes $171 million and $250 million of outstanding commercial paper as of June 30, 2021 and December 31, 2020, respectively.

Derivative Instruments and He_3

Derivative Instruments and Hedging Activities Quantitative Disclosures Related to Derivative Instruments (Details) - Not Designated as Hedging Instrument bbl in Thousands, MMBTU in Millions		6 Months Ended	12 Months Ended
		Jun. 30, 2021MMBTUbbl	Dec. 31, 2020MMBTUbbl
Natural gas, Financial fixed futures/swaps | Purchases
Derivative [Line Items]
Derivative, gross notional volume (TBtu) | MMBTU	[1]	0	0
Natural gas, Financial fixed futures/swaps | Sales
Derivative [Line Items]
Derivative, gross notional volume (TBtu) | MMBTU	[1]	8	18
Natural gas, Financial basis futures/swaps | Purchases
Derivative [Line Items]
Derivative, gross notional volume (TBtu) | MMBTU	[1]	0	0
Natural gas, Financial basis futures/swaps | Sales
Derivative [Line Items]
Derivative, gross notional volume (TBtu) | MMBTU	[1]	22	27
Natural gas, Financial swaptions | Purchases
Derivative [Line Items]
Derivative, gross notional volume (TBtu) | MMBTU	[1],[2]	0	0
Natural gas, Financial swaptions | Sales
Derivative [Line Items]
Derivative, gross notional volume (TBtu) | MMBTU	[1],[2]	4	7
Natural gas, Physical purchases/sales | Purchases
Derivative [Line Items]
Derivative, gross notional volume (TBtu) | MMBTU	[1]	0	0
Natural gas, Physical purchases/sales | Sales
Derivative [Line Items]
Derivative, gross notional volume (TBtu) | MMBTU	[1]	0	0
Crude oil, Financial Futures/swaps | Purchases
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Volume | bbl	[3]	0	0
Crude oil, Financial Futures/swaps | Sales
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Volume | bbl	[3]	270	465
Crude oil, Financial options | Purchases
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Volume | bbl	[2],[3]	0	0
Crude oil, Financial options | Sales
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Volume | bbl	[2],[3]	90	90
Natural gas liquids, Financial Futures/swaps | Purchases
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Volume | bbl	[4]	45	855
Natural gas liquids, Financial Futures/swaps | Sales
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Volume | bbl	[4]	525	1,210
Natural gas liquids, Options | Purchases
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Volume | bbl	[4]	0	0
Natural gas liquids, Options | Sales
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Volume | bbl	[4]	15	45
Natural gas
Derivative [Line Items]
Percent of contract with durations of one year or less		98.70%	95.70%
Percent of contracts with durations of more than one year and less than two years		1.30%	4.30%
Crude oil (for condensate)
Derivative [Line Items]
Percent of contract with durations of one year or less		91.70%	100.00%
Percent of contracts with durations of more than one year and less than two years		8.30%
Natural gas liquids
Derivative [Line Items]
Percent of contract with durations of one year or less		94.90%	100.00%
Percent of contracts with durations of more than one year and less than two years		5.10%
[1]	As of June 30, 2021, 98.7% of the natural gas contracts had durations of one year or less and 1.3% had durations of more than one year and less than two years. As of December 31, 2020, 95.7% of the natural gas contracts had durations of one year or less and 4.3% had durations of more than one year and less than two years.
[2]	The notional volume contains a combined derivative instrument consisting of a fixed price swap and a sold option, which gives the counterparties the right, but not the obligation, to increase the notional volume hedged under the fixed price swap until the option expiration date. The notional volume represents the volume prior to option exercise.
[3]	As of June 30, 2021, 91.7% of the crude oil (for condensate) contracts had durations of one year or less and 8.3% had durations of more than one year and less than two years. As of December 31, 2020, 100.0% of the crude oil (for condensate) contracts had durations of one year or less.
[4]	As of June 30, 2021, 94.9% of the natural gas liquids contracts had durations of one year or less and 5.1% had durations of more than one year and less than two years. As of December 31, 2020, 100.0% of the natural gas liquids contracts had durations of one year or less.

Derivative Instruments and He_4

Derivative Instruments and Hedging Activities - Derivative Instruments Designated as Hedging Instruments (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Designated as Hedging Instrument | Interest Rate Swap
Derivative [Line Items]
Interest rate swaps	$ 300	$ 300

Derivative Instruments and He_5

Derivative Instruments and Hedging Activities - Balance Sheet Location (Details) - USD ($) $ in Millions		Jun. 30, 2021	Dec. 31, 2020
Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative asset	[1]	$ 4	$ 19
Derivative liability	[1]	35	21
Interest rate swaps | Designated as Hedging Instrument | Other Current Assets
Derivatives, Fair Value [Line Items]
Derivative asset	[2]	0	0
Interest rate swaps | Designated as Hedging Instrument | Other Current Liabilities
Derivatives, Fair Value [Line Items]
Derivative liability	[2]	3	6
Natural gas | Financial futures/swaps | Not Designated as Hedging Instrument | Other Current Assets
Derivatives, Fair Value [Line Items]
Derivative asset		0	2
Natural gas | Financial futures/swaps | Not Designated as Hedging Instrument | Other Current Liabilities
Derivatives, Fair Value [Line Items]
Derivative liability		9	2
Natural gas | Financial swaptions | Not Designated as Hedging Instrument | Other Current Assets
Derivatives, Fair Value [Line Items]
Derivative asset		0	1
Natural gas | Financial swaptions | Not Designated as Hedging Instrument | Other Current Liabilities
Derivatives, Fair Value [Line Items]
Derivative liability		6	2
Crude oil (for condensate) | Financial futures/swaps | Not Designated as Hedging Instrument | Other Current Assets
Derivatives, Fair Value [Line Items]
Derivative asset		0	1
Crude oil (for condensate) | Financial futures/swaps | Not Designated as Hedging Instrument | Other Current Liabilities
Derivatives, Fair Value [Line Items]
Derivative liability		7	13
Crude oil (for condensate) | Financial swaptions | Not Designated as Hedging Instrument | Other Current Assets
Derivatives, Fair Value [Line Items]
Derivative asset		0	0
Crude oil (for condensate) | Financial swaptions | Not Designated as Hedging Instrument | Other Current Liabilities
Derivatives, Fair Value [Line Items]
Derivative liability		1	0
Crude oil (for condensate) | Financial swaptions | Not Designated as Hedging Instrument | Other Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative asset		0	0
Crude oil (for condensate) | Financial swaptions | Not Designated as Hedging Instrument | Other Liabilities
Derivatives, Fair Value [Line Items]
Derivative liability		1	0
Natural gas liquids | Financial futures/swaps | Not Designated as Hedging Instrument | Other Current Assets
Derivatives, Fair Value [Line Items]
Derivative asset		4	15
Natural gas liquids | Financial futures/swaps | Not Designated as Hedging Instrument | Other Current Liabilities
Derivatives, Fair Value [Line Items]
Derivative liability		10	3
Natural gas liquids | Financial swaptions | Not Designated as Hedging Instrument | Other Current Assets
Derivatives, Fair Value [Line Items]
Derivative asset		0	0
Natural gas liquids | Financial swaptions | Not Designated as Hedging Instrument | Other Current Liabilities
Derivatives, Fair Value [Line Items]
Derivative liability		$ 1	$ 1
[1]	See Note 11 for a reconciliation of the Partnership’s commodity derivatives fair value to the Partnership’s Condensed Consolidated Balance Sheets as of June 30, 2021 and December 31, 2020.
[2]	All interest rate derivative instruments that were designated as cash flow hedges are considered Level 2 as of June 30, 2021 and December 31, 2020.

Derivative Instruments and He_6

Derivative Instruments and Hedging Activities - Amounts Recognized in Income (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Derivative Instruments, Gain (Loss) [Line Items]
Change in fair value of commodity derivatives	$ (19)	$ (12)	$ (29)	$ (2)
Realized gains (losses) on commodity derivatives	(10)	7	(14)	17
Gains (losses) on commodity derivative activity	(29)	(5)	(43)	15
Cash collateral posted	1		1
Cash collateral required if ratings are lowered	6		6
Interest Rate Swap
Derivative Instruments, Gain (Loss) [Line Items]
Interest rate swaps losses	(2)	(1)	(3)	(1)
Natural gas | Financial futures/swaps
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on commodity derivative activity	(11)	(1)	(13)	3
Natural gas | Financial swaptions
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on commodity derivative activity	(5)	(1)	(5)	(2)
Natural gas | Natural gas, Physical purchases/sales
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on commodity derivative activity	0	0	0	1
Condensate | Financial futures/swaps
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on commodity derivative activity	(6)	(7)	(12)	12
Condensate | Financial swaptions
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on commodity derivative activity	(1)	(2)	(2)	2
Natural gas liquids | Financial futures/swaps
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on commodity derivative activity	$ (6)	$ 6	$ (11)	$ (1)

Fair Value Measurements - Carry

Fair Value Measurements - Carrying and Fair Value Amounts (Details) - USD ($) $ in Millions		Jun. 30, 2021	Dec. 31, 2020
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Commercial paper		$ 171	$ 250
Carrying Amount | Significant other observable inputs (Level 2) | Revolving Credit Facility
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Revolving Credit Facility (Level 2)	[1]	0	0
Carrying Amount | Significant other observable inputs (Level 2) | 2019 Term Loan Agreement | 2019 Term Loan Agreement
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
2019 Term Loan Agreement (Level 2)		800	800
Carrying Amount | Significant other observable inputs (Level 2) | Senior Notes | 2024 Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior Notes (Level 2)		600	600
Carrying Amount | Significant other observable inputs (Level 2) | Senior Notes | 2027 Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior Notes (Level 2)		698	698
Carrying Amount | Significant other observable inputs (Level 2) | Senior Notes | 2028 Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior Notes (Level 2)		796	795
Carrying Amount | Significant other observable inputs (Level 2) | Senior Notes | 2029 Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior Notes (Level 2)		546	546
Carrying Amount | Significant other observable inputs (Level 2) | Senior Notes | 2044 Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior Notes (Level 2)		531	531
Fair Value | Significant other observable inputs (Level 2) | Revolving Credit Facility
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Revolving Credit Facility (Level 2)	[1]	0	0
Fair Value | Significant other observable inputs (Level 2) | 2019 Term Loan Agreement | 2019 Term Loan Agreement
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
2019 Term Loan Agreement (Level 2)		800	800
Fair Value | Significant other observable inputs (Level 2) | Senior Notes | 2024 Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior Notes (Level 2)		639	612
Fair Value | Significant other observable inputs (Level 2) | Senior Notes | 2027 Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior Notes (Level 2)		774	709
Fair Value | Significant other observable inputs (Level 2) | Senior Notes | 2028 Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior Notes (Level 2)		916	817
Fair Value | Significant other observable inputs (Level 2) | Senior Notes | 2029 Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior Notes (Level 2)		599	544
Fair Value | Significant other observable inputs (Level 2) | Senior Notes | 2044 Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior Notes (Level 2)		578	499
Commercial Paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Commercial paper	[2]	$ 171	$ 250
[1]	Borrowing capacity is effectively reduced by our borrowings outstanding under the commercial paper program. $171 million and $250 million of commercial paper was outstanding as of June 30, 2021 and December 31, 2020, respectively.
[2]	Short-term debt includes $171 million and $250 million of outstanding commercial paper as of June 30, 2021 and December 31, 2020, respectively.

Fair Value Measurements - Fair

Fair Value Measurements - Fair Value Hierarchy (Details) - USD ($) $ in Millions		Jun. 30, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Retained fuel due from shippers		$ 14	$ 19
Retained fuel due to shippers		3	3
Commodity Contracts | Recurring Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, total fair value		4	19
Liabilities, total fair value		35	21
Asset netting adjustments		(4)	(19)
Liability netting adjustments		(4)	(19)
Total assets		0	0
Total Liabilities		31	2
Commodity Contracts | Recurring Measurement | Quoted market prices in active market for identical assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets		0	2
Liabilities		11	14
Commodity Contracts | Recurring Measurement | Significant other observable inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets		4	17
Liabilities		24	7
Gas Imbalances | Recurring Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, total fair value	[1],[2]	14	23
Liabilities, total fair value	[2],[3]	11	16
Asset netting adjustments	[1],[2]	0	0
Liability netting adjustments	[2],[3]	0	0
Total assets	[1],[2]	14	23
Total Liabilities	[2],[3]	11	16
Gas Imbalances | Recurring Measurement | Quoted market prices in active market for identical assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	[1],[2]	0	0
Liabilities	[2],[3]	0	0
Gas Imbalances | Recurring Measurement | Significant other observable inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	[1],[2]	14	23
Liabilities	[2],[3]	$ 11	$ 16
[1]	Gas imbalance assets exclude fuel reserves for under retained fuel due from shippers of $14 million and $19 million at June 30, 2021 and December 31, 2020, respectively, which fuel reserves are based on the value of natural gas at the time the imbalance was created, and which are not subject to revaluation at fair market value.
[2]	The Partnership uses the market approach to fair value its gas imbalance assets and liabilities at individual, or where appropriate an average of, current market indices applicable to the Partnership’s operations, not to exceed net realizable value. There were no netting adjustments as of June 30, 2021 and December 31, 2020.
[3]	Gas imbalance liabilities exclude fuel reserves for over retained fuel due to shippers of $3 million and $3 million at June 30, 2021 and December 31, 2020, respectively, which fuel reserves are based on the value of natural gas at the time the imbalance was created, and which are not subject to revaluation at fair market value.

Supplemental Disclosure of Ca_3

Supplemental Disclosure of Cash Flow Information - Supplemental Disclosure of Cash Flow Information (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Interest, net of capitalized interest and debt AFUDC	$ 81	$ 96
Income taxes, net of refunds	(1)	1
Accounts payable related to capital expenditures	6	8
Lease liabilities related to derecognition of right-of-use assets	0	5
Partners' Capital, Including Portion Attributable to Noncontrolling Interest	7,193	7,317	$ 7,181	$ 7,095	$ 7,352	$ 7,409
Common Unit [Member] | Partners' Capital
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Partners' Capital, Including Portion Attributable to Noncontrolling Interest	6,809	$ 6,937	$ 6,798	$ 6,713	$ 6,972	7,013
Cumulative Effect, Period of Adoption, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Partners' Capital, Including Portion Attributable to Noncontrolling Interest						(3)
Cumulative Effect, Period of Adoption, Adjustment | Common Unit [Member] | Partners' Capital
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Partners' Capital, Including Portion Attributable to Noncontrolling Interest	$ 0					$ (3)

Related Party Transactions - Na

Related Party Transactions - Narrative (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Related Party Transaction [Line Items]
Partnership's revenues from affiliated companies as a percent of total revenues	6.00%	7.00%
Subsidiary of Common Parent | CenterPoint | Three Services Included in Transportation and Storage Agreements
Related Party Transaction [Line Items]
Period of written notice	180 days
CenterPoint and OGE Energy | Minimum
Related Party Transaction [Line Items]
Period notice of termination for reimbursements for all employee costs	90 days
OGE Energy | Defined Benefit and Retiree Medical Plans
Related Party Transaction [Line Items]
Expense reimbursement, 2018 and thereafter	$ 5
OGE Energy | Certain Services and Support Functions
Related Party Transaction [Line Items]
Expense reimbursement annual caps	1
CenterPoint | Certain Services and Support Functions
Related Party Transaction [Line Items]
Expense reimbursement annual caps	$ 1

Related Party Transactions - Re

Related Party Transactions - Related Party Activity (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Related Party Transaction [Line Items]
Revenues from affiliated companies	$ 32	$ 33	$ 100	$ 84
Cost of natural gas purchases from affiliated companies	12	6	43	15
CenterPoint
Related Party Transaction [Line Items]
Cost of natural gas purchases from affiliated companies	0	0	0	1
CenterPoint | Gas Transportation and Storage
Related Party Transaction [Line Items]
Revenues from affiliated companies	16	22	43	59
CenterPoint | Gas Sales
Related Party Transaction [Line Items]
Revenues from affiliated companies	5	1	5	1
OGE Energy
Related Party Transaction [Line Items]
Cost of natural gas purchases from affiliated companies	12	6	43	14
OGE Energy | Gas Transportation and Storage
Related Party Transaction [Line Items]
Revenues from affiliated companies	9	10	19	19
OGE Energy | Gas Sales
Related Party Transaction [Line Items]
Revenues from affiliated companies	2	0	33	5
OGE Energy | Seconded Employee Costs
Related Party Transaction [Line Items]
Seconded employee costs	$ 3	$ 5	$ 7	$ 8

Commitments and Contingencies (

Commitments and Contingencies (Details) - USD ($) $ in Millions	Sep. 13, 2018	Jan. 01, 2017	Jun. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
Gathering and processing agreement term (in years)		10 years
Minimum volume commitment fee			$ 159
Minimum volume commitment fees remaining in current year			10
Minimum volume commitment fees per year from 2022 through 2027			23
Minimum volume commitment fees in 2028			11
Estimated Cost to Complete Pipeline Project			$ 540
Firm transportation service agreement term (in years)	20 years

Equity-Based Compensation (Deta

Equity-Based Compensation (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total compensation expense	$ 4	$ 3	$ 8	$ 7
Performance units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total compensation expense	2	2	4	4
Phantom units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total compensation expense	$ 2	$ 1	$ 4	$ 3

Equity-Based Compensation - Per

Equity-Based Compensation - Performance Units (Details) - Performance units	6 Months Ended
	Jun. 30, 2021$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of units granted | shares	1,453,897	[1]
Fair value of units granted | $ / shares	$ 10.26	[1]
Expected distribution yield	12.90%
Expected price volatility	100.00%
Risk-free interest rate	0.27%
Expected life of units (in years)	3 years
[1]	Performance units represents the target number of performance units granted. The actual number of performance units earned, if any, is dependent upon performance and may range from 0% to 200% of the target.

Equity-Based Compensation - Pha

Equity-Based Compensation - Phantom Units (Details) - Phantom units	6 Months Ended
	Jun. 30, 2021$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Phantom Units granted | shares	1,371,001	[1]
Fair value of phantom units granted (in dollars per share)	$ 6.86	[1]
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of phantom units granted (in dollars per share)	5.41
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of phantom units granted (in dollars per share)	$ 6.87
[1]	Performance units represents the target number of performance units granted. The actual number of performance units earned, if any, is dependent upon performance and may range from 0% to 200% of the target.

Equity-Based Compensation - Equ

Equity-Based Compensation - Equity Units Activity (Details) $ / shares in Units, $ in Millions	6 Months Ended
	Jun. 30, 2021USD ($)$ / sharesshares
Performance units
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Units Outstanding (in units) | shares	1,765,508
Granted (in units) | shares	1,453,897	[1]
Vested (in units) | shares	(389,817)	[2]
Forfeited (in units) | shares	(45,945)
Units Outstanding (in units) | shares	2,783,643
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Units Outstanding (in dollars per unit)	$ 13.10
Granted (in dollars per unit)	10.26	[1]
Vested (in dollars per unit)	17.70	[2]
Forfeited (in dollars per unit)	9.94
Units Outstanding (in dollars per unit)	$ 11.02
Aggregate Intrinsic Value of Units Outstanding | $	$ 25
Performance units | Minimum
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Payout percentage	0.00%
Performance units | Maximum
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Payout percentage	200.00%
Performance units | Annual Grant in 2018 [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Granted (in units) | shares	389,817
Phantom units
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Units Outstanding (in units) | shares	1,790,845
Granted (in units) | shares	1,371,001	[1]
Vested (in units) | shares	(469,488)	[2]
Forfeited (in units) | shares	(119,851)
Units Outstanding (in units) | shares	2,572,507
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Units Outstanding (in dollars per unit)	$ 10.29
Granted (in dollars per unit)	6.86	[1]
Vested (in dollars per unit)	13.07	[2]
Forfeited (in dollars per unit)	8.51
Units Outstanding (in dollars per unit)	$ 8.03
Aggregate Intrinsic Value of Units Outstanding | $	$ 23
Phantom units | Minimum
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Granted (in dollars per unit)	$ 5.41
Phantom units | Maximum
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Granted (in dollars per unit)	$ 6.87
[1]	Performance units represents the target number of performance units granted. The actual number of performance units earned, if any, is dependent upon performance and may range from 0% to 200% of the target.
[2]	Performance units vested as of June 30, 2021 include 389,817 units from the 2018 annual grant, which were approved by the Board of Directors in 2018 and, based on the level of achievement of a performance goal established by the Board of Directors over the performance period of January 1, 2018 through December 31, 2020, no performance units vested.

Equity-Based Compensation - Unr

Equity-Based Compensation - Unrecognized Compensation Cost (Details) $ in Millions	6 Months Ended
	Jun. 30, 2021USD ($)shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized Compensation Cost (In millions)	$ 31
Performance units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized Compensation Cost (In millions)	$ 19
Weighted Average Period for Recognition (In years)	2 years
Phantom units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized Compensation Cost (In millions)	$ 12
Weighted Average Period for Recognition (In years)	1 year 10 months 2 days
Long Term Incentive Plan | Common Unit [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for issuance | shares	3,118,170

Reportable Segments - Schedule

Reportable Segments - Schedule of Financial Data for Business Segments and Services (Details) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2021USD ($)	Jun. 30, 2020USD ($)	Jun. 30, 2021USD ($)segment		Jun. 30, 2020USD ($)		Dec. 31, 2020USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | segment				2
Total Revenues		$ 787	$ 515	$ 1,757		$ 1,163
Cost of natural gas and natural gas liquids (excluding depreciation and amortization shown separately)		426	177	945		403
Operation and maintenance, General and administrative		116	136	237		262
Depreciation and amortization		103	105	209		209
Impairments of property, plant and equipment and goodwill		0	0	0		28
Taxes other than income tax		18	17	36		35
Operating Income		124	80	330		226
Total assets		11,759		11,759				$ 11,729
Capital expenditures (excluding equity AFUDC)		71	48	151		102
Operating Segments | Gathering and Processing
Segment Reporting Information [Line Items]
Total Revenues		673	391	1,297		868
Cost of natural gas and natural gas liquids (excluding depreciation and amortization shown separately)		437	176	835		387
Operation and maintenance, General and administrative		73	92	152		173
Depreciation and amortization		74	74	148		148
Impairments of property, plant and equipment and goodwill						28
Taxes other than income tax		11	11	22		22
Operating Income		78	38	140		110
Total assets		10,824		10,824				10,830
Capital expenditures (excluding equity AFUDC)		20	24	41		58
Operating Segments | Transportation and Storage
Segment Reporting Information [Line Items]
Total Revenues		253	183	735	[1]	417	[1]
Cost of natural gas and natural gas liquids (excluding depreciation and amortization shown separately)		128	59	385	[1]	137	[1]
Operation and maintenance, General and administrative		44	45	86	[1]	90	[1]
Depreciation and amortization		29	31	61	[1]	61	[1]
Impairments of property, plant and equipment and goodwill	[1]					0
Taxes other than income tax		7	6	14	[1]	13	[1]
Operating Income		45	42	189	[1]	116	[1]
Total assets	[1]	5,917		5,917				5,729
Capital expenditures (excluding equity AFUDC)		51	24	110	[1]	44	[1]
Eliminations
Segment Reporting Information [Line Items]
Total Revenues		(139)	(59)	(275)		(122)
Cost of natural gas and natural gas liquids (excluding depreciation and amortization shown separately)		(139)	(58)	(275)		(121)
Operation and maintenance, General and administrative		(1)	(1)	(1)		(1)
Depreciation and amortization		0	0	0		0
Impairments of property, plant and equipment and goodwill						0
Taxes other than income tax		0	0	0		0
Operating Income		1	0	1		0
Total assets		(4,982)		(4,982)				$ (4,830)
Capital expenditures (excluding equity AFUDC)		0	0	0		0
Product
Segment Reporting Information [Line Items]
Total Revenues		460	196	1,087		484
Product | Operating Segments | Gathering and Processing
Segment Reporting Information [Line Items]
Total Revenues		461	193	889		468
Product | Operating Segments | Transportation and Storage
Segment Reporting Information [Line Items]
Total Revenues		135	59	467	[1]	134	[1]
Product | Eliminations
Segment Reporting Information [Line Items]
Total Revenues		(136)	(56)	(269)		(118)
Natural Gas, Gathering, Transportation, Marketing and Processing
Segment Reporting Information [Line Items]
Total Revenues		327	319	670		679
Natural Gas, Gathering, Transportation, Marketing and Processing | Operating Segments | Gathering and Processing
Segment Reporting Information [Line Items]
Total Revenues		212	198	408		400
Natural Gas, Gathering, Transportation, Marketing and Processing | Operating Segments | Transportation and Storage
Segment Reporting Information [Line Items]
Total Revenues		118	124	268	[1]	283	[1]
Natural Gas, Gathering, Transportation, Marketing and Processing | Eliminations
Segment Reporting Information [Line Items]
Total Revenues		$ (3)	$ (3)	$ (6)		$ (4)
[1]	See Note 8 for discussion regarding ownership interests in SESH and related equity earnings included in the transportation and storage segment for the three and six months ended June 30, 2021 and 2020.