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Number of reportable segments | segment

Number of representatives designated by each of CenterPoint Energy and OGE Energy | board_member

Number of independent board members | board_member

Minimum percentage of vote required by all unitholders

75.00%

Deferred revenues

$ 48,000,000

$ 34,000,000

$ 48,000,000

$ 34,000,000

Cash and cash equivalents

950,000,000

^[1]

$ 928,000,000

$ 805,000,000

$ 748,000,000

806,000,000

^[1]

$ 705,000,000

$ 626,000,000

$ 666,000,000

3,431,000,000

2,803,000,000

$ 2,272,000,000

Environmental exit costs

8,000,000

5,000,000

8,000,000

5,000,000

Restricted cash

14,000,000

Allowance for doubtful accounts receivable

2,000,000

3,000,000

2,000,000

3,000,000

Regulatory liabilities

$ 23,000,000

$ 21,000,000

23,000,000

21,000,000

AFUDC, capitalized interest

$ 6,000,000

1,000,000

4,000,000

Participant contribution percentage, maximum

70.00%

Employer matching contribution percentage

100.00%

Employer matching contribution percentage, percent of participant's eligible compensation

6.00%

Partnership contributions

$ 19,000,000

18,000,000

16,000,000

Materials and Supplies

Write down of materials and supplies inventory

1,000,000

Natural gas

Write down of materials and supplies inventory

$ 4,000,000

$ 2,000,000

$ 3,000,000

SESH

Other Revenue [Member] | Customer Concentration Risk

50.00%

Ownership percentage

50.00%

Total revenue | Customer Concentration Risk

0.00%

CenterPoint | Common Units

10.00%

OGE Energy | Common Units

233,856,623

110,982,805

Atoka

Limited Partner | CenterPoint

50.00%

Percentage share of management rights

50.00%

Percentage share of incentive distribution rights

40.00%

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

54.00%

Preferred units outstanding (in units) | shares

14,520,000

Limited Partner | CenterPoint | Subordinated Units

Limited Partner | OGE Energy

139,704,916

Percentage share of management rights

50.00%

Percentage share of incentive distribution rights

60.00%

Limited Partner | OGE Energy | Subordinated Units

25.60%

Third Party One | Volume of natural gas liquids | Customer Concentration Risk

68,150,514

Third Party One | Total revenue | Customer Concentration Risk

12.00%

13.00%

22.00%

6.00%

5.00%

6.00%

Third Party Two | Volume of natural gas liquids | Customer Concentration Risk

^[1]

$ 214,000,000

$ 140,000,000

$ 129,000,000

Third Party Two | Total revenue | Customer Concentration Risk

8.00%

12.00%

4.00%

^[1]

$ 152,000,000

$ 127,000,000

VPP

Defined Benefit And Retiree Medical Plans | OGE Energy

60.00%

Reimbursement of benefits

$ 3,000,000

$ 5,000,000

$ 7,000,000

[1]	The Partnership had no external customers accounting for 10% or more of Total revenues in periods shown. See Note 15 for revenues from affiliated companies.

Summary of Significant Accounting Policies - Inventory (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Materials and supplies	$ 31	$ 29
Natural gas and natural gas liquids inventories	19	11
Total Inventory	$ 50	$ 40

Revenue - Disaggregation of Revenue (Details) - USD ($)
$ in Millions

3 Months Ended

12 Months Ended

Dec. 31, 2018

^[1]

Sep. 30, 2018

^[1]

Jun. 30, 2018

^[1]

Mar. 31, 2018

^[1]

Dec. 31, 2017

^[1]

Sep. 30, 2017

^[1]

Jun. 30, 2017

^[1]

Mar. 31, 2017

^[1]

Dec. 31, 2018

Dec. 31, 2017

Dec. 31, 2016

Total revenues from natural gas, natural gas liquids, and condensate

$ 2,095

$ 19

$ (43)

$ 950

$ 928

$ 805

$ 748

$ 806

$ 705

$ 626

$ 666

3,431

2,803

2,272

Natural gas

Total revenues from natural gas, natural gas liquids, and condensate

564

Natural gas liquids

Total revenues from natural gas, natural gas liquids, and condensate

1,405

Condensate Natural Gas

Total revenues from natural gas, natural gas liquids, and condensate

126

Product

2,106

1,653

1,172

Demand Service Revenue

Volume Dependant Service Revenue

724

Natural Gas, Gathering, Transportation, Marketing and Processing

601

Operating Segments | Gathering and Processing

1,325

1,150

1,100

Total revenues from natural gas, natural gas liquids, and condensate

2,011

Operating Segments | Gathering and Processing | Natural gas

2,818

2,170

1,640

Total revenues from natural gas, natural gas liquids, and condensate

480

Operating Segments | Gathering and Processing | Natural gas liquids

Total revenues from natural gas, natural gas liquids, and condensate

1,405

Operating Segments | Gathering and Processing | Condensate Natural Gas

Total revenues from natural gas, natural gas liquids, and condensate

126

Operating Segments | Gathering and Processing | Product

Operating Segments | Gathering and Processing | Demand Service Revenue

2,016

1,538

1,081

Operating Segments | Gathering and Processing | Volume Dependant Service Revenue

252

Operating Segments | Gathering and Processing | Natural Gas, Gathering, Transportation, Marketing and Processing

550

Operating Segments | Transportation and Storage

802

632

559

Total revenues from natural gas, natural gas liquids, and condensate

620

Operating Segments | Transportation and Storage | Natural gas

1,162

1,146

1,024

Total revenues from natural gas, natural gas liquids, and condensate

590

Operating Segments | Transportation and Storage | Natural gas liquids

Total revenues from natural gas, natural gas liquids, and condensate

Operating Segments | Transportation and Storage | Condensate Natural Gas

Total revenues from natural gas, natural gas liquids, and condensate

Operating Segments | Transportation and Storage | Product

Operating Segments | Transportation and Storage | Demand Service Revenue

625

621

479

Operating Segments | Transportation and Storage | Volume Dependant Service Revenue

472

Operating Segments | Transportation and Storage | Natural Gas, Gathering, Transportation, Marketing and Processing

537

525

545

Eliminations

Total revenues from natural gas, natural gas liquids, and condensate

(536)

Eliminations | Natural gas

(549)

(513)

(392)

Total revenues from natural gas, natural gas liquids, and condensate

(506)

Eliminations | Natural gas liquids

Total revenues from natural gas, natural gas liquids, and condensate

(30)

Eliminations | Condensate Natural Gas

Total revenues from natural gas, natural gas liquids, and condensate

Eliminations | Product

Eliminations | Demand Service Revenue

(535)

(506)

(388)

Eliminations | Volume Dependant Service Revenue

Eliminations | Natural Gas, Gathering, Transportation, Marketing and Processing

(14)

New Accounting Pronouncements or Change in Accounting Principle [Line Items]

$ (14)

$ (7)

$ (4)

[1]	The Partnership had no external customers accounting for 10% or more of Total revenues in periods shown. See Note 15 for revenues from affiliated companies.

Revenue - Accounts Receivable (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Customers	$ 297	$ 265
Contract assets	6	27
Non-customers	6	3
Total Accounts Receivable	309	$ 295
Decrease in contract assets	21
Firm Service Transportation [Member]
Disaggregation of Revenue [Line Items]
Contract assets	$ 3

Revenue - Summary of Changes in Contract Liabilities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
2018	$ 25
Deferred revenues	48
2019	5
2020	5
2021	5
2023 and After	8
Calculated under Revenue Guidance in Effect before Topic 606
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Deferred revenues		$ 34
Accounting Standards Update 2014-09 \| Difference between Revenue Guidance in Effect before and after Topic 606
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Deferred revenues	$ 19

Revenue - Summary of Recognition Contract Liabilities (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($)
Revenue from Contract with Customer [Abstract]
2018	$ 25
2019	5
2020	5
2021	5
2023 and After	$ 8

Revenue - Summary of the Impact of the Changes on Revenues (Details) - USD ($)
$ in Millions

3 Months Ended

12 Months Ended

Dec. 31, 2018

^[1]

Sep. 30, 2018

^[1]

Jun. 30, 2018

^[1]

Mar. 31, 2018

^[1]

Dec. 31, 2017

^[1]

Sep. 30, 2017

^[1]

Jun. 30, 2017

^[1]

Mar. 31, 2017

^[1]

Dec. 31, 2018

Dec. 31, 2017

Dec. 31, 2016

Total revenues from natural gas, natural gas liquids, and condensate

$ 2,095

$ 19

$ (43)

New Accounting Pronouncements or Change in Accounting Principle [Line Items]

$ 950

$ 928

$ 805

$ 748

$ 806

$ 705

$ 626

$ 666

3,431

2,803

2,272

Natural gas

Total revenues from natural gas, natural gas liquids, and condensate

564

Natural gas liquids

New Accounting Pronouncements or Change in Accounting Principle [Line Items]

Total revenues from natural gas, natural gas liquids, and condensate

1,405

Condensate Natural Gas

New Accounting Pronouncements or Change in Accounting Principle [Line Items]

Total revenues from natural gas, natural gas liquids, and condensate

126

Product

New Accounting Pronouncements or Change in Accounting Principle [Line Items]

New Accounting Pronouncements or Change in Accounting Principle [Line Items]

2,106

1,653

1,172

Demand Service Revenue

Volume Dependant Service Revenue

724

New Accounting Pronouncements or Change in Accounting Principle [Line Items]

Natural Gas, Gathering, Transportation, Marketing and Processing

601

New Accounting Pronouncements or Change in Accounting Principle [Line Items]

Calculated under Revenue Guidance in Effect before Topic 606

1,325

$ 1,150

$ 1,100

New Accounting Pronouncements or Change in Accounting Principle [Line Items]

Total revenues from natural gas, natural gas liquids, and condensate

2,195

Calculated under Revenue Guidance in Effect before Topic 606 | Natural gas

3,507

New Accounting Pronouncements or Change in Accounting Principle [Line Items]

Total revenues from natural gas, natural gas liquids, and condensate

635

Calculated under Revenue Guidance in Effect before Topic 606 | Natural gas liquids

New Accounting Pronouncements or Change in Accounting Principle [Line Items]

Total revenues from natural gas, natural gas liquids, and condensate

1,434

Calculated under Revenue Guidance in Effect before Topic 606 | Condensate Natural Gas

New Accounting Pronouncements or Change in Accounting Principle [Line Items]

Total revenues from natural gas, natural gas liquids, and condensate

126

Calculated under Revenue Guidance in Effect before Topic 606 | Product

New Accounting Pronouncements or Change in Accounting Principle [Line Items]

Calculated under Revenue Guidance in Effect before Topic 606 | Demand Service Revenue

2,206

New Accounting Pronouncements or Change in Accounting Principle [Line Items]

Calculated under Revenue Guidance in Effect before Topic 606 | Volume Dependant Service Revenue

724

New Accounting Pronouncements or Change in Accounting Principle [Line Items]

Calculated under Revenue Guidance in Effect before Topic 606 | Natural Gas, Gathering, Transportation, Marketing and Processing

577

New Accounting Pronouncements or Change in Accounting Principle [Line Items]

Difference between Revenue Guidance in Effect before and after Topic 606

1,301

New Accounting Pronouncements or Change in Accounting Principle [Line Items]

Total revenues from natural gas, natural gas liquids, and condensate

(100)

Difference between Revenue Guidance in Effect before and after Topic 606 | Natural gas

(76)

New Accounting Pronouncements or Change in Accounting Principle [Line Items]

Total revenues from natural gas, natural gas liquids, and condensate

(71)

Difference between Revenue Guidance in Effect before and after Topic 606 | Natural gas liquids

New Accounting Pronouncements or Change in Accounting Principle [Line Items]

Total revenues from natural gas, natural gas liquids, and condensate

(29)

Difference between Revenue Guidance in Effect before and after Topic 606 | Condensate Natural Gas

New Accounting Pronouncements or Change in Accounting Principle [Line Items]

Total revenues from natural gas, natural gas liquids, and condensate

Difference between Revenue Guidance in Effect before and after Topic 606 | Product

New Accounting Pronouncements or Change in Accounting Principle [Line Items]

Difference between Revenue Guidance in Effect before and after Topic 606 | Demand Service Revenue

(100)

New Accounting Pronouncements or Change in Accounting Principle [Line Items]

Difference between Revenue Guidance in Effect before and after Topic 606 | Volume Dependant Service Revenue

New Accounting Pronouncements or Change in Accounting Principle [Line Items]

Difference between Revenue Guidance in Effect before and after Topic 606 | Natural Gas, Gathering, Transportation, Marketing and Processing

New Accounting Pronouncements or Change in Accounting Principle [Line Items]

Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]

$ 24

[1]	The Partnership had no external customers accounting for 10% or more of Total revenues in periods shown. See Note 15 for revenues from affiliated companies.

Acquisitions - Narrative (Details) $ in Millions			12 Months Ended
Acquisitions - Narrative (Details) $ in Millions	Nov. 01, 2018 USD ($) mi	Oct. 04, 2017 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
General and Administrative Expense
Business Acquisition [Line Items]
Acquisition costs associated with the transaction (less than $1 million)			$ 6
Velocity Holdings, LLC
Business Acquisition [Line Items]
Aggregate purchase price	$ 444
Percentage of Pipeline System Acquired	60.00%
Number of Miles in Pipeline System Acquired \| mi	26
Less: Noncontrolling interest at fair value	$ 28
Align Midstream, LLC
Business Acquisition [Line Items]
Aggregate purchase price		$ 298
Align Midstream, LLC \| General and Administrative Expense
Business Acquisition [Line Items]
Acquisition costs associated with the transaction (less than $1 million)				$ 2
Customer Relationships
Business Acquisition [Line Items]
Weighted average useful life (in years)			14 years
Customer Relationships \| Velocity Holdings, LLC
Business Acquisition [Line Items]
Weighted average useful life (in years)			15 years
Customer Relationships \| Align Midstream, LLC
Business Acquisition [Line Items]
Weighted average useful life (in years)		10 years

Acquisitions - Schedule of Assets and Liabilities Assumed (Details) - USD ($) $ in Millions	Dec. 31, 2018	Nov. 01, 2018	Dec. 31, 2017	Oct. 04, 2017	Dec. 31, 2016
Assets acquired:
Goodwill	$ 98		$ 12		$ 0
Velocity Holdings, LLC
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents		$ 1
Assets acquired:
Accounts receivable		3
Property, plant and equipment		124
Other intangible assets		259
Goodwill		86
Liabilities assumed:
Current liabilities		1
Less: Noncontrolling interest at fair value		28
Total identifiable net assets		$ 444
Align Midstream, LLC
Assets acquired:
Accounts receivable				$ 5
Property, plant and equipment				111
Other intangible assets				176
Goodwill				12
Liabilities assumed:
Current liabilities				6
Total identifiable net assets				$ 298

Earnings Per Limited Partner Unit (Details) - USD ($)
$ / shares in Units, shares in Millions

3 Months Ended

12 Months Ended

Dec. 31, 2018

Sep. 30, 2018

Jun. 30, 2018

Mar. 31, 2018

Dec. 31, 2017

Sep. 30, 2017

Jun. 30, 2017

Mar. 31, 2017

Dec. 31, 2018

Dec. 31, 2017

Dec. 31, 2016

Net income

$ 175,000,000

$ 139,000,000

$ 95,000,000

$ 114,000,000

$ 108,000,000

$ 113,000,000

$ 96,000,000

$ 120,000,000

$ 523,000,000

$ 437,000,000

$ 313,000,000

Net income attributable to noncontrolling interests

2,000,000

1,000,000

Series A Preferred Unit distributions

36,000,000

22,000,000

General partner interest in net income

Net Income Attributable to Common and Subordinated Units (Note 5)

$ 165,000,000

$ 129,000,000

$ 86,000,000

$ 105,000,000

$ 99,000,000

$ 104,000,000

$ 86,000,000

$ 111,000,000

485,000,000

400,000,000

290,000,000

Dilutive effect of Series A Preferred Unit distribution

0.00

Diluted net income (loss)

$ 485,000,000

$ 400,000,000

$ 290,000,000

Basic weighted average number of outstanding

Basic weighted average number of outstanding

434

433

424

Diluted weighted average number of outstanding units

436

434

424

Common Units

Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]

Net Income Attributable to Common and Subordinated Units (Note 5)

$ 485,000,000

$ 273,000,000

$ 148,000,000

Diluted net income (loss)

$ 485,000,000

$ 273,000,000

$ 148,000,000

Basic weighted average number of outstanding

Basic weighted average number of outstanding

434

296

216

Dilutive effect of Series A Preferred Units (in units)

$ 0.38

$ 0.30

$ 0.20

$ 0.24

$ 0.23

$ 0.24

$ 0.20

$ 0.26

$ 1.12

$ 0.92

$ 0.69

Dilutive effect of performance units (in units)

Diluted weighted average number of outstanding units

436

297

216

Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]

0.38

0.30

0.20

0.24

0.23

0.24

0.20

0.26

$ 1.11

$ 0.92

$ 0.69

Subordinated Units

Net Income Attributable to Common and Subordinated Units (Note 5)

$ 0

$ 127,000,000

$ 142,000,000

Diluted net income (loss)

$ 0

$ 127,000,000

$ 142,000,000

Basic weighted average number of outstanding

Basic weighted average number of outstanding

137

208

Diluted weighted average number of outstanding units

0.00

^[1]

0.00

^[1]

0.00

^[1]

0.00

^[1]

0.00

0.24

0.20

0.25

$ 0.00

$ 0.93

$ 0.68

137

208

Performance Units, Restricted Units, and Phantom Units

$ 0.00

^[1]

$ 0.00

^[1]

$ 0.00

^[1]

$ 0.00

^[1]

$ 0.00

$ 0.24

$ 0.20

$ 0.25

$ 0.00

$ 0.93

$ 0.68

Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]

Dilutive effect of unit-based awards (in dollars per unit) (less than $.01)

$ 0.01

Phantom units

Dilutive effect of performance units (in units)

[1]	(1)See Note 6 for discussion of the conversion of the subordinated units.

Enable Midstream Partners, LP Partners' Equity - Schedule of Cash Distributions (Details) - USD ($)

1 Months Ended

Feb. 26, 2019

Feb. 14, 2019

Feb. 08, 2019

Nov. 29, 2018

Nov. 16, 2018

Nov. 14, 2018

Nov. 06, 2018

Aug. 28, 2018

Aug. 21, 2018

Aug. 14, 2018

Aug. 01, 2018

May 29, 2018

May 22, 2018

May 15, 2018

May 14, 2018

May 01, 2018

Feb. 27, 2018

Feb. 20, 2018

Feb. 15, 2018

Feb. 09, 2018

Nov. 21, 2017

Nov. 14, 2017

Oct. 31, 2017

Aug. 29, 2017

Aug. 22, 2017

Aug. 14, 2017

Jul. 31, 2017

May 30, 2017

May 23, 2017

May 12, 2017

May 02, 2017

Feb. 28, 2017

Feb. 21, 2017

Feb. 15, 2017

Feb. 10, 2017

Nov. 22, 2016

Nov. 14, 2016

Nov. 01, 2016

Aug. 23, 2016

Aug. 16, 2016

Aug. 12, 2016

Aug. 02, 2016

May 13, 2016

May 06, 2016

Mar. 31, 2016

Distribution Made to Limited Partner [Line Items]

Nov. 16, 2018

Aug. 21, 2018

May 22, 2018

Feb. 20, 2018

Nov. 14, 2017

Aug. 22, 2017

May 23, 2017

Feb. 21, 2017

Nov. 14, 2016

Aug. 16, 2016

May 06, 2016

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

Nov. 29, 2018

Aug. 28, 2018

May 29, 2018

Feb. 27, 2018

Nov. 21, 2017

Aug. 29, 2017

May 30, 2017

Feb. 28, 2017

Nov. 22, 2016

Aug. 23, 2016

May 13, 2016

Distribution Made to Limited Partner [Line Items]

Nov. 06, 2018

Aug. 01, 2018

May 01, 2018

Feb. 09, 2018

Oct. 31, 2017

Jul. 31, 2017

May 02, 2017

Feb. 10, 2017

Nov. 01, 2016

Aug. 02, 2016

May 06, 2016

Distribution Made to Limited Partner [Line Items]

Nov. 14, 2018

Aug. 14, 2018

May 15, 2018

Feb. 15, 2018

Nov. 14, 2017

Aug. 14, 2017

May 12, 2017

Feb. 15, 2017

Nov. 14, 2016

Aug. 12, 2016

May 13, 2016

Cash Distribution

Per unit distribution, paid (in dollars per unit)

$ 0.318

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

$ 138,000,000

$ 137,000,000

$ 134,000,000

Distribution Made to Limited Partner [Line Items]

Per unit distribution, paid (in dollars per unit)

$ 0.625

$ 0.2917

Full quarter equivalent distribution declared (in dollars per unit)

$ 9,000,000

$ 4,000,000

$ 0.625

Annualized distribution declared (in dollars per unit)

$ 2.50

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

Distribution Made to Limited Partner [Line Items]

Subsequent Event | Cash Distribution

^[1]

Feb. 08, 2019

Distribution Made to Limited Partner [Line Items]

Common unit cash distribution declared (in dollars per unit)

^[2]

$ 138,000,000

^[2]

$ 0.318

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]

Common unit cash distribution declared (in dollars per unit)

^[1]

$ 0.625

Subsequent Event | Scenario, Forecast

Distribution Made to Limited Partner [Line Items]

^[2]

Feb. 19, 2019

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

^[2]

Feb. 26, 2019

Distribution Made to Limited Partner [Line Items]

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

^[1]

Feb. 14, 2019

Distribution Made to Limited Partner [Line Items]

Schedule of Equity Method Investments [Line Items]

^[3]

$ 9,000,000

[1]	The board of directors of Enable GP declared this $0.625 per Series A Preferred Unit cash distribution on February 8, 2019, which was paid on February 14, 2019 to Series A Preferred unitholders of record at the close of business on February 8, 2019.
[2]	The board of directors of Enable GP declared this $0.318 per common unit cash distribution on February 8, 2019, to be paid on February 26, 2019, to common unitholders of record at the close of business on February 19, 2019.
[3]	The prorated quarterly distribution for the Series A Preferred Units is for a partial period beginning on February 18, 2016, and ending on March 31, 2016, which equates to $0.625 per unit on a full-quarter basis or $2.50 per unit on an annualized basis.

Enable Midstream Partners, LP Partners' Equity - Narrative (Details) - USD ($)					12 Months Ended
	Aug. 30, 2017	May 12, 2017	Nov. 29, 2016	Feb. 18, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Distribution Made to Limited Partner [Line Items]
Limited partners' capital account, required quarterly distribution period					60 days
Conversion ratio	100.00%
Limited partners capital account, minimum quarterly distribution, annualized					150.00%
Proceeds from issuance of Series A Preferred Units, net of issuance costs					$ 0	$ 0	$ 362,000,000
Number of common units in public offering			75,719
Limited Partner \| CenterPoint
Distribution Made to Limited Partner [Line Items]
Amount notes redeemed payable to wholly-owned subsidiary of CenterPoint Energy				$ 363,000,000
Series A 10% Fixed to Floating Non Cumulative Redeemable Perpetual Preferred Units
Distribution Made to Limited Partner [Line Items]
Annual percentage rate				10.00%
Liquidation preference (in dollars per share)				$ 25.00
Duration of cash distributions				5 years
Redemption price (in dollars per share)				$ 25.50
Series A 10% Fixed to Floating Non Cumulative Redeemable Perpetual Preferred Units \| LIBOR
Distribution Made to Limited Partner [Line Items]
Annual percentage rate				8.50%
Private Placement \| Series A 10% Fixed to Floating Non Cumulative Redeemable Perpetual Preferred Units
Distribution Made to Limited Partner [Line Items]
Issuance of Series A Preferred Units (in units)				14,520,000
Cash purchase price (in dollars per unit)				$ 25.00
Proceeds from issuance of Series A Preferred Units, net of issuance costs				$ 362,000,000
Expenses related to offering				$ 1,000,000
ATM Program
Distribution Made to Limited Partner [Line Items]
Aggregate offering price		$ 200,000,000			$ 2,000,000	$ 303,000
Number of common units in public offering					140,920	18,500
Common units remained available for issuance through the ATM Program					$ 197,000,000
Commissions					$ 25,000	$ 3,000
Public Offering
Distribution Made to Limited Partner [Line Items]
Number of common units in public offering			10,000,000
Public offering price (in dollars per share)			$ 14.00
Proceeds received (net of underwriting discounts, structuring fees, and offering expenses)			$ 137,000,000
Over-Allotment Option
Distribution Made to Limited Partner [Line Items]
Number of common units in public offering			1,500,000
Over-Allotment Option \| Affiliate of ArcLight Capital Partners, LLC
Distribution Made to Limited Partner [Line Items]
Number of common units in public offering			1,424,281
Subordinated Units \| Limited Partner \| OGE Energy
Distribution Made to Limited Partner [Line Items]
Units outstanding (in units)						68,150,514
Subordinated Units \| Limited Partner \| CenterPoint
Distribution Made to Limited Partner [Line Items]
Units outstanding (in units)						139,704,916
Distribution Subordination Period 1
Distribution Made to Limited Partner [Line Items]
Limited partners' capital account, minimum annualized quarterly distribution (in dollars per unit)					$ 1.15
Distribution Subordination Period 2
Distribution Made to Limited Partner [Line Items]
Limited partners' capital account, maximum annualized quarterly distribution (in dollars per unit)					$ 1.725
Maximum
Distribution Made to Limited Partner [Line Items]
Limited partners' capital account, incentive distribution rights, percentage					50.00%	50.00%
Minimum
Distribution Made to Limited Partner [Line Items]
Incentive distribution, distribution (in dollars per unit)					$ 0.330625	$ 0.330625
Subordinated Units
Distribution Made to Limited Partner [Line Items]
Units outstanding (in units)	207,855,430

Property, Plant and Equipment - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 12,899	$ 12,079
Accumulated depreciation	2,028	1,724
Property, plant and equipment, net	10,871	10,355
Depreciation expense	$ 351	335	$ 311
Gathering and Processing
Property, Plant and Equipment [Line Items]
Weighted Average Useful Lives (Years)	37 years
Property, plant and equipment, gross	$ 8,011	7,322
Accumulated depreciation	$ 1,063	865
Transportation and Storage
Property, Plant and Equipment [Line Items]
Weighted Average Useful Lives (Years)	36 years
Property, plant and equipment, gross	$ 4,740	4,538
Accumulated depreciation	965	859
Construction work-in-progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 148	$ 219

Intangible Assets, Net - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Amortization expense	$ 47	$ 31	$ 27
Expected amortization of intangible assets, 2019	62
Expected amortization of intangible assets, 2020	62
Expected amortization of intangible assets, 2021	62
Expected amortization of intangible assets, 2022	62
Expected amortization of intangible assets, 2023	62
Customer Relationships
Finite-Lived Intangible Assets [Line Items]
Total intangible assets	840	581
Accumulated amortization	177	130
Net intangible assets	$ 663	$ 451
Weighted average useful life (in years)	14 years

Goodwill - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
Goodwill - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Goodwill [Roll Forward]
Goodwill	$ 12	$ 0
Goodwill	98	12
Gathering and Processing
Goodwill [Roll Forward]
Goodwill	12	0
Goodwill	98	12
Transportation and Storage
Goodwill [Roll Forward]
Goodwill	0	0
Goodwill	0	0
Align Midstream, LLC
Goodwill [Roll Forward]
Goodwill acquired		12
Align Midstream, LLC \| Gathering and Processing
Goodwill [Roll Forward]
Goodwill acquired		12
Align Midstream, LLC \| Transportation and Storage
Goodwill [Roll Forward]
Goodwill acquired		$ 0
Velocity Holdings, LLC
Goodwill [Roll Forward]
Goodwill acquired	86
Velocity Holdings, LLC \| Gathering and Processing
Goodwill [Roll Forward]
Goodwill acquired	86
Velocity Holdings, LLC \| Transportation and Storage
Goodwill [Roll Forward]
Goodwill acquired	$ 0

Investment in Equity Method Affiliate - Narrative (Details) - USD ($)
$ in Millions

3 Months Ended

12 Months Ended

Dec. 31, 2018

Sep. 30, 2018

^[1]

Jun. 30, 2018

^[1]

Mar. 31, 2018

^[1]

Dec. 31, 2017

^[1]

Sep. 30, 2017

^[1]

Jun. 30, 2017

^[1]

Mar. 31, 2017

^[1]

Dec. 31, 2018

Dec. 31, 2017

Dec. 31, 2016

Schedule of Equity Method Investments [Line Items]

$ 950

^[1]

$ 928

$ 805

$ 748

$ 806

$ 705

$ 626

$ 666

$ 3,431

$ 2,803

$ 2,272

SESH

Ownership percentage

50.00%

SESH | Shared Operations Service Agreements | Equity Method Investee

Schedule of Equity Method Investments [Line Items]

SESH | Spectra Energy Partners, LP

$ 18

$ 17

$ 13

Schedule of Equity Method Investments [Line Items]

Ownership percentage

50.00%

Percentage distributions

50.00%

[1]	The Partnership had no external customers accounting for 10% or more of Total revenues in periods shown. See Note 15 for revenues from affiliated companies.

Investment in Equity Method Affiliate - Schedule of Investments (Details) - USD ($)
$ in Millions

12 Months Ended

Dec. 31, 2018

Dec. 31, 2017

Dec. 31, 2016

Investment in Equity Method Affiliates:

Equity in earnings of equity method affiliate

$ 26

$ 28

Distributions from unconsolidated affiliates

Return of investment

(7)

(5)

(15)

SESH

Investment in Equity Method Affiliates:

Equity in earnings of equity method affiliate

Distributions from equity method affiliate

^[1]

(33)

(43)

Distributions from unconsolidated affiliates

Return of investment

$ (7)

$ (5)

$ (15)

[1]	Distributions from equity method affiliate includes a $26 million, $28 million and $28 million return on investment and a $7 million, $5 million and $15 million return of investment for the years ended December 31, 2018, 2017 and 2016, respectively.

- Definition

This item represents the entity's proportionate share for the period of the net income (loss) of its investee (such as unconsolidated subsidiaries and joint ventures) to which the equity method of accounting is applied. This item includes income or expense related to stock-based compensation based on the investor's grant of stock to employees of an equity method investee.

+ References + Details

Investment in Equity Method Affiliate - Financial Information of SESH (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Balance Sheet Data:
Investment in SESH	$ 317	$ 324
SESH
Balance Sheet Data:
Current assets	30	32
Property, plant and equipment, net	1,078	1,093
Total assets	1,108	1,125
Current liabilities	13	14
Long-term debt	397	397
Members’ equity	698	714
Total liabilities and members’ equity	1,108	1,125
Investment in SESH	317	324
Less: Capitalized interest on investment in SESH	(1)	(1)
Add: Basis differential, net of amortization	33	34
The Partnership’s share of members’ equity	349	357
Income Statement Data:
Revenues	112	113	$ 115
Operating income	67	72	73
Net income	$ 50	$ 54	$ 55

Debt - Schedule of Outstanding Debt (Details) - USD ($)

Dec. 31, 2018

May 10, 2018

Dec. 31, 2017

Debt Instrument, Unamortized Discount (Premium), Net

$ 4,299,000,000

$ 3,455,000,000

1,000,000

(10,000,000)

Debt Issuance Costs, Gross

4,298,000,000

3,465,000,000

20,000,000

15,000,000

Long-term Debt, Excluding Current Maturities

3,129,000,000

2,595,000,000

Long-term Debt, before Debt Issuance Costs, Net, Current Maturities

^[1]

500,000,000

Loans Payable | Term Loan Facility in 2015 [Member]

Debt Instrument, Unamortized Discount (Premium), Net

450,000,000

Long-term Debt, before Debt Issuance Costs, Net, Current Maturities

450,000,000

450,000,000

Senior Notes | 2019 Notes (Level 2)

Debt Instrument, Unamortized Discount (Premium), Net

500,000,000

Senior Notes | 2024 Notes (Level 2)

500,000,000

Debt Instrument, Unamortized Discount (Premium), Net

600,000,000

Senior Notes | 2027 Notes (Level 2)

600,000,000

Debt Instrument, Unamortized Discount (Premium), Net

700,000,000

(2,000,000)

(3,000,000)

Senior Notes | 2028 Notes (Level 2)

698,000,000

697,000,000

Debt Instrument, Unamortized Discount (Premium), Net

800,000,000

(6,000,000)

794,000,000

Less: Unamortized debt expense

$ 800,000,000

7,000,000

Senior Notes | 2044 Notes (Level 2)

Debt Instrument, Unamortized Discount (Premium), Net

550,000,000

Senior Notes | 6.25% Senior Notes

550,000,000

Revolving Credit Facility

250,000,000

Debt Instrument, Unamortized Discount (Premium), Net

250,000,000

Debt Issuance Costs, Line of Credit Arrangements, Net

250,000,000

6,000,000

3,000,000

Debt Instrument, Unamortized Discount (Premium), Net

Short-term debt

649,000,000

^[2]

405,000,000

Subsidiary of Common Parent | Senior Notes | EOIT Senior Notes [Member]

Debt Instrument, Unamortized Discount (Premium), Net

250,000,000

7,000,000

13,000,000

$ 257,000,000

$ 263,000,000

[1]	As of December 31, 2018, Current portion of long-term debt includes the $500 million outstanding balance of the 2019 Notes due May 15, 2019. At December 31, 2017, Current portion of long-term debt included the $450 million outstanding balance of the 2015 Term Loan Agreement which
[2]	Short-term debt includes $649 million and $405 million of commercial paper outstanding as of December 31, 2018 and 2017, respectively.

Debt - Maturities of Long Term Debt (Details) $ in Millions	Dec. 31, 2018 USD ($)
Debt Disclosure [Abstract]
Long-term debt maturities in 2019	$ 1,149
Long-term debt maturities in 2020	250
Long-term debt maturities in 2021	0
Long-term debt maturities in 2022	0
Long-term debt maturities in 2023	250
Thereafter	$ 2,650

Debt - Narrative (Details)

12 Months Ended

May 10, 2018

USD ($)

Apr. 06, 2018

USD ($)

time

Jul. 31, 2015

USD ($)

Dec. 31, 2018

USD ($)

Dec. 31, 2017

USD ($)

Commercial paper, authorized

$ 1,400,000,000

Revolving Credit Facility

Debt Issuance Costs, Line of Credit Arrangements, Net

6,000,000

$ 3,000,000

Maximum borrowing capacity

$ 1,750,000,000

Letters of credit principal advances

250,000,000

Letters of credit outstanding amount

$ 3,000,000

Unused capacity, commitment fee percentage

0.20%

Covenant, acceleration of indebtedness, threshold amount

$ 100,000,000

Covenant, acceleration of indebtedness, nonpayment of uninsured money judgments, threshold amount

$ 100,000,000

Term loan facility, term

5 years

Line of Credit Facility, Increase in Maximum Borrowing Capacity

$ 875,000,000

Number of times option may be exercised | time

Additional term of loan

1 year

Revolving Credit Facility | LIBOR

Basis spread on variable rate percentage

1.50%

Revolving Credit Facility | Minimum

Threshold for debt covenant ratio

$ 25,000,000

Revolving Credit Facility | Maximum

Consolidated debt to EBITDA ratio

5.00

Threshold for debt covenant ratio for acquisitions

5.50

Unsecured Debt | 2015 Term Loan Facility

Term loan facility, term

3 years

Senior Notes | 2028 Notes (Level 2)

$ 450,000,000

Fixed percentage interest rate

$ 800,000,000

4.95%

Proceeds from Issuance of Senior Long-term Debt

$ 787,000,000

Unamortized discount

$ 6,000,000

Unamortized debt expense

$ 7,000,000

Senior Notes | 2027 Notes (Level 2)

5.21%

Senior Notes | 2.400% Senior Notes

4.58%

Senior Notes | 3.900% Senior Notes

2.57%

Senior Notes | 5.000% Senior Notes

4.02%

Senior Notes | Senior Notes including 2019 Notes, 2024 Notes, and 2044 Notes

5.08%

Senior Notes | 6.25% Senior Notes

Unamortized discount

$ 2,000,000

Unamortized debt expense

13,000,000

$ 250,000,000

Weighted average interest rate percentage

3.40%

Subsidiary of Common Parent | Senior Notes | Senior Notes, Due March 2020 at 6.25%

$ 649,000,000

^[1]

$ 405,000,000

Premium (Discount) on long-term debt

$ 7,000,000

Subsidiary of Common Parent | Senior Notes | 6.25% Senior Notes

3.83%

[1]	Short-term debt includes $649 million and $405 million of commercial paper outstanding as of December 31, 2018 and 2017, respectively.

Derivative Instruments and Hedging Activities - Quantitative Disclosures Related to Derivative Instruments (Details)
bbl in Thousands, MMBTU in Millions, $ in Millions

12 Months Ended

Dec. 31, 2018

USD ($)

MMBTU

bbl

Dec. 31, 2017

USD ($)

MMBTU

bbl

Designated cash flow hedges | $

$ 0.0

Fair value hedges | $

$ 0.0

Not Designated as Hedging Instrument | Financial fixed futures/swaps | Purchases

Not Designated as Hedging Instrument | Financial fixed futures/swaps | Sales

Not Designated as Hedging Instrument | Financial basis futures/swaps | Purchases

Not Designated as Hedging Instrument | Financial basis futures/swaps | Sales

Not Designated as Hedging Instrument | Financial swaptions - natural gas | Purchases

Not Designated as Hedging Instrument | Financial swaptions - natural gas | Sales

^[1]

Not Designated as Hedging Instrument | Physical purchases/sales | Purchases

^[1]

1,000

Not Designated as Hedging Instrument | Physical purchases/sales | Sales

Not Designated as Hedging Instrument | Financial futures/swaps- Crude oil (for condensate) | Purchases

Not Designated as Hedging Instrument | Financial futures/swaps- Crude oil (for condensate) | Sales

Not Designated as Hedging Instrument | Financial swaptions - crude oil | Purchases

945

564

Not Designated as Hedging Instrument | Financial swaptions - crude oil | Sales

^[1]

Not Designated as Hedging Instrument | Financial futures/swaps- Natural gas liquids | Purchases

^[1]

30,000

Not Designated as Hedging Instrument | Financial futures/swaps- Natural gas liquids | Sales

270

Not Designated as Hedging Instrument | Natural gas

2,535

1,615

Percent of contract with durations of one year or less

74.00%

67.70%

Percent of contracts with durations of more than one year and less than two years

24.20%

16.10%

Percent of contracts having durations of more than two years

1.80%

16.20%

Not Designated as Hedging Instrument | Crude oil (for condensate)

Percent of contract with durations of one year or less

76.90%

100.00%

Percent of contracts with durations of more than one year and less than two years

23.10%

Not Designated as Hedging Instrument | Volume of natural gas liquids

Percent of contract with durations of one year or less

86.10%

100.00%

Percent of contracts with durations of more than one year and less than two years

13.90%

[1]	As of December 31, 2018, 76.9% of the crude oil (for condensate) contracts had durations of one year or less and 23.1% had durations of more than one year and less than two years. As of December 31, 2017, 100% of the crude oil (for condensate) contracts had durations of one year or less.

Derivative Instruments and Hedging Activities - Balance Sheet Location (Details) - Not Designated as Hedging Instrument - USD ($)
$ in Millions

Dec. 31, 2018

Dec. 31, 2017

Natural gas | Financial futures/swaps | Other Current Assets

Derivative Asset

^[1]

$ 33

$ 9

Derivative Liability

^[1]

Natural gas | Financial futures/swaps | Other Current Liabilities

Natural gas | Financial futures/swaps | Other Noncurrent Assets

Natural gas | Financial futures/swaps | Other Noncurrent Liabilities

Natural gas | Physical purchases/sales | Other Current Assets

Natural gas | Physical purchases/sales | Other Current Liabilities

Natural gas | Physical purchases/sales | Other Noncurrent Assets

Natural gas | Physical purchases/sales | Other Noncurrent Liabilities

Crude oil (for condensate) | Financial futures/swaps | Other Current Assets

Crude oil (for condensate) | Financial futures/swaps | Other Current Liabilities

Crude oil (for condensate) | Financial futures/swaps | Other Noncurrent Assets

Crude oil (for condensate) | Financial futures/swaps | Other Noncurrent Liabilities

Crude oil (for condensate) | Financial swaptions | Other Noncurrent Assets

Crude oil (for condensate) | Financial swaptions | Other Noncurrent Liabilities

Natural gas liquids financial futures/swaps | Financial futures/swaps | Other Current Assets

Natural gas liquids financial futures/swaps | Financial futures/swaps | Other Current Liabilities

Natural gas liquids financial futures/swaps | Financial futures/swaps | Other Noncurrent Assets

Natural gas liquids financial futures/swaps | Financial futures/swaps | Other Noncurrent Liabilities

$ 0

[1]	See Note 13 for a reconciliation of the Partnership’s total derivatives fair value to the Partnership’s Consolidated Balance Sheets as of December 31, 2018 and 2017.

Derivative Instruments and Hedging Activities - Amounts Recognized in Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivative, net	$ 11	$ 19	$ (43)
Change in fair value of derivatives	26	28	(60)
Realized (loss) gain on derivatives	(15)	(9)	17
Gain (loss) on derivative activity	11	19	(43)
Cash collateral already posted	0
Cash collateral posted	0
Natural gas \| Physical purchases/sales
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivative, net			(19)
Natural gas \| Physical purchases/sales
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivative, net	7	9
Natural gas \| Financial futures/swaps
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivative, net	(8)	20	(7)
Crude oil (for condensate) \| Financial futures/swaps
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivative, net	6	(1)	(4)
Crude oil (for condensate) \| Financial swaptions
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivative, net	0	0	0
Natural gas liquids financial futures/swaps \| Financial futures/swaps
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on derivative, net	$ 6	$ (9)	$ (13)

Fair Value Measurements - Estimated Fair Value of Financial Instruments and Non-Financial Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis (Details) - USD ($)

Dec. 31, 2018

Dec. 31, 2017

Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]

Revolving Credit Facility (Level 2) | Carrying Amount | Significant other observable inputs (Level 2) | Revolving Credit Facility (Level 2)

$ 649,000,000

^[1]

$ 405,000,000

Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]

Lines of Credit, Fair Value Disclosure

250,000,000

Revolving Credit Facility (Level 2) | Fair Value | Significant other observable inputs (Level 2) | Revolving Credit Facility (Level 2)

Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]

Lines of Credit, Fair Value Disclosure

250,000,000

Loans Payable | Carrying Amount | Significant other observable inputs (Level 2) | 2015 Term Loan Agreement (Level 2)

Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]

Loans Payable, Fair Value Disclosure

450,000,000

Loans Payable | Fair Value | Significant other observable inputs (Level 2) | 2015 Term Loan Agreement (Level 2)

Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]

Loans Payable, Fair Value Disclosure

450,000,000

Senior Notes | Carrying Amount | 2028 Notes (Level 2)

Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]

Senior Notes | Carrying Amount | Significant other observable inputs (Level 2) | 2019 Notes (Level 2)

794,000,000

Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]

Senior Notes | Carrying Amount | Significant other observable inputs (Level 2) | 2024 Notes (Level 2)

500,000,000

Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]

Senior Notes | Carrying Amount | Significant other observable inputs (Level 2) | 2027 Notes (Level 2)

600,000,000

Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]

Senior Notes | Carrying Amount | Significant other observable inputs (Level 2) | 2044 Notes (Level 2)

698,000,000

697,000,000

Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]

Senior Notes | Fair Value | 2028 Notes (Level 2)

550,000,000

Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]

Senior Notes | Fair Value | Significant other observable inputs (Level 2) | 2019 Notes (Level 2)

764,000,000

Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]

Senior Notes | Fair Value | Significant other observable inputs (Level 2) | 2024 Notes (Level 2)

497,000,000

Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]

Senior Notes | Fair Value | Significant other observable inputs (Level 2) | 2027 Notes (Level 2)

571,000,000

602,000,000

Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]

Senior Notes | Fair Value | Significant other observable inputs (Level 2) | 2044 Notes (Level 2)

642,000,000

712,000,000

Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]

Subsidiary of Common Parent | Senior Notes | Carrying Amount | Significant other observable inputs (Level 2) | EOIT Senior Notes (Level 2)

445,000,000

550,000,000

Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]

Subsidiary of Common Parent | Senior Notes | Fair Value | Significant other observable inputs (Level 2) | EOIT Senior Notes (Level 2)

257,000,000

263,000,000

Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

$ 256,000,000

$ 265,000,000

[1]	Short-term debt includes $649 million and $405 million of commercial paper outstanding as of December 31, 2018 and 2017, respectively.

Fair Value Measurements - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairments	$ 0	$ 0	$ 9
Service Star Assets \| Gathering and Processing \| Income Approach Valuation Technique \| Fair Value, Measurements, Nonrecurring \| Unobservable inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairments			9
Property, Plant and Equipment \| Service Star Assets \| Gathering and Processing \| Income Approach Valuation Technique \| Fair Value, Measurements, Nonrecurring \| Unobservable inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairments			8
Materials and Supplies \| Service Star Assets \| Gathering and Processing \| Income Approach Valuation Technique \| Fair Value, Measurements, Nonrecurring \| Unobservable inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairments			$ 1

Fair Value Measurements - Fair Value Hierarchy (Details) - USD ($)

Dec. 31, 2018

Dec. 31, 2017

Fuel reserves for under retained fuel due from shippers

$ 11,000,000

$ 10,000,000

Fuel reserves for over retained fuel due from shippers

5,000,000

Recurring Measurement | Commodity Contracts

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Derivative asset, fair value, before netting adjustments

33,000,000

9,000,000

Derivative liability, fair value, before netting adjustments

11,000,000

13,000,000

Derivative asset, netting adjustment

(9,000,000)

(5,000,000)

Derivative liability, netting adjustment

(9,000,000)

(5,000,000)

Derivative Asset

24,000,000

4,000,000

Fair Value

2,000,000

8,000,000

Recurring Measurement | Gas Imbalances

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Derivative asset, fair value, before netting adjustments

18,000,000

27,000,000

Derivative liability, fair value, before netting adjustments

17,000,000

12,000,000

Derivative asset, netting adjustment

^[1],[2]

Derivative liability, netting adjustment

Derivative Asset

18,000,000

27,000,000

Fair Value

17,000,000

12,000,000

Recurring Measurement | Quoted market prices in active market for identical assets (Level 1) | Commodity Contracts

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

4,000,000

5,000,000

Recurring Measurement | Quoted market prices in active market for identical assets (Level 1) | Gas Imbalances

9,000,000

3,000,000

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Recurring Measurement | Significant other observable inputs (Level 2) | Commodity Contracts

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

29,000,000

4,000,000

Recurring Measurement | Significant other observable inputs (Level 2) | Gas Imbalances

2,000,000

5,000,000

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

18,000,000

27,000,000

Recurring Measurement | Unobservable inputs (Level 3) | Commodity Contracts

17,000,000

12,000,000

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Recurring Measurement | Unobservable inputs (Level 3) | Gas Imbalances

5,000,000

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

$ 0

[1]	Gas imbalance assets exclude fuel reserves for under retained fuel due from shippers of $11 million and $10 million at December 31, 2018 and 2017, 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 December 31, 2018 and 2017.

Fair Value Measurements - Schedule of Changes in Fair Values of Level 3 Financial Assets (Details) - Natural gas liquids financial futures/swaps - Commodity Contracts - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning Balance	$ (5)	$ (8)
Losses included in earnings	(23)	(9)
Settlements	7	(12)
Transfers out of Level 3	(21)	0
Ending Balance	$ 0	$ (5)

Supplemental Disclosure of Cash Flow Information - Supplemental Disclosure of Cash Flow Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Supplemental Cash Flow Information [Abstract]
Interest, net of capitalized interest	$ 148	$ 114	$ 105
Income taxes, net of refunds	3	0	0
Accounts payable related to capital expenditures	$ 54	$ 39	$ 18

Supplemental Disclosure of Cash Flow Information - Schedule of Reconciliation of Cash and Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Supplemental Cash Flow Information [Abstract]
Cash and cash equivalents	$ 8	$ 5
Restricted cash	14	14
Cash, cash equivalents and restricted cash shown in the Consolidated Statement of Cash Flows	$ 22	$ 19	$ 23	$ 4

Related Party Transactions - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions		12 Months Ended
	Feb. 18, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Related Party Transaction [Line Items]
Partnership's revenues from affiliated companies as a percent of total revenues		5.00%	5.00%	7.00%
Rent and maintenance expense		$ 35	$ 27	$ 27
Proceeds from issuance of Series A Preferred Units, net of issuance costs		$ 0	$ 0	$ 362
Private Placement \| Series A 10% Fixed to Floating Non Cumulative Redeemable Perpetual Preferred Units
Related Party Transaction [Line Items]
Issuance of Series A Preferred Units (in units)	14,520,000
Cash purchase price (in dollars per unit)	$ 25.00
Proceeds from issuance of Series A Preferred Units, net of issuance costs	$ 362
CenterPoint and OGE Energy \| Minimum
Related Party Transaction [Line Items]
Period notice of termination for reimbursements for all employee costs		90 days
CenterPoint \| Certain Services and Support Functions
Related Party Transaction [Line Items]
Expense reimbursement annual caps		$ 4
OGE Energy \| Minimum
Related Party Transaction [Line Items]
Period notice of termination prior to commencement of succeeding annual period		180 days	180 days
OGE Energy \| Defined Benefit And Retiree Medical Plans
Related Party Transaction [Line Items]
Expense reimbursement in 2018		$ 5
OGE Energy \| Certain Services and Support Functions
Related Party Transaction [Line Items]
Expense reimbursement annual caps		1
Subsidiary of Common Parent \| Amount Reimbursed for Costs Incurred in Modifications of Acquired Facility \| Pipelines
Related Party Transaction [Line Items]
Amount of reimbursement		$ 1	$ 1
CenterPoint \| Subsidiary of Common Parent \| Three Services included in Transportation and Storage Agreements
Related Party Transaction [Line Items]
Period of written notice prior to contract termination		180 days
CenterPoint \| Affiliate \| Lease Agreement with Affiliate of CenterPoint Energy
Related Party Transaction [Line Items]
Rent and maintenance expense		$ 1

Related Party Transactions - Related Party Activity (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Related Party Transaction [Line Items]
Revenues from affiliated companies	$ 163	$ 153	$ 159
Cost of goods sold from affiliate	26	20	14
Total corporate services, operating lease and seconded employee expense	32	38	40
CenterPoint
Related Party Transaction [Line Items]
Cost of goods sold from affiliate	3	1	0
CenterPoint \| Gas Transportation and Storage
Related Party Transaction [Line Items]
Revenues from affiliated companies	111	110	110
CenterPoint \| Gas Sales
Related Party Transaction [Line Items]
Revenues from affiliated companies	11	6	1
CenterPoint \| Corporate Services
Related Party Transaction [Line Items]
Total corporate services, operating lease and seconded employee expense	1	3	6
CenterPoint \| Operating Lease
Related Party Transaction [Line Items]
Total corporate services, operating lease and seconded employee expense	1	1	0
OGE Energy
Related Party Transaction [Line Items]
Cost of goods sold from affiliate	23	19	14
OGE Energy \| Gas Transportation and Storage
Related Party Transaction [Line Items]
Revenues from affiliated companies	37	35	36
OGE Energy \| Gas Sales
Related Party Transaction [Line Items]
Revenues from affiliated companies	4	2	12
OGE Energy \| Seconded Employee Costs
Related Party Transaction [Line Items]
Total corporate services, operating lease and seconded employee expense	29	31	29
OGE Energy \| Corporate Services
Related Party Transaction [Line Items]
Total corporate services, operating lease and seconded employee expense	$ 1	$ 3	$ 5

Commitments and Contingencies - Operating Leases Future Minimum Payments and Other Commitments (Details) $ in Millions	Dec. 31, 2018 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Noncancellable operating leases due in 2019	$ 14
Noncancellable operating leases due in 2020	3
Noncancellable operating leases due in 2021	3
Noncancellable operating leases due in 2022	3
Noncancellable operating leases due in 2023	3
Noncancellable operating leases due after 2023	14
Total	$ 40

Commitments and Contingencies - Narrative (Details)			12 Months Ended			87 Months Ended	96 Months Ended
Commitments and Contingencies - Narrative (Details)	Sep. 13, 2018	Jan. 01, 2017 MMcf	Dec. 31, 2018 USD ($) ft² agreement	Dec. 31, 2017 USD ($) ft²	Dec. 31, 2016 USD ($)	Jun. 30, 2019 USD ($)	Dec. 31, 2025 USD ($)	Aug. 28, 2018 ft²
Lessee, Lease, Description [Line Items]
Number of compression service agreements \| agreement			110
Number of compression service agreements on a month-to-month basis \| agreement			46
Number of compression service agreements expiring in 2019 \| agreement			60
Number of compression service agreements expiring in 2020 \| agreement			4
Number of gas treating agreements \| agreement			7
Agreement term		10 years
Supply Commitment, Minimum Energy Volume Required per Day \| MMcf		400
Supply Commitment, Minimum Volume Commitment Fee			$ 215,000,000
Supply Commitment, Minimum Volume Commitment Fees Next Nine Years			23,000,000
Supply Commitment, Minimum Volume Commitment Fees Year Ten			11,000,000
Estimated Cost to Complete Pipeline Project			550,000,000
Rent and maintenance expenses expected to incur during the remaining term of lease			40,000,000
Noncancellable operating leases due in 2019			14,000,000
Noncancellable operating leases due in 2020			3,000,000
Firm transportation service agreement term	20 years
Rent expense			$ 35,000,000	$ 27,000,000	$ 27,000,000
Principal executive offices
Lessee, Lease, Description [Line Items]
Area of leased office space (square feet) \| ft²			162,053
Houston, Texas
Lessee, Lease, Description [Line Items]
Area of leased office space (square feet) \| ft²				48,642
Bank of Oklahoma Park Plaza
Lessee, Lease, Description [Line Items]
Operating Leases, Square Feet of Building \| ft²								154,584
Rent and maintenance expenses expected to incur during the remaining term of lease			$ 25,000,000
Noncancellable operating leases due in 2019			1,000,000
Noncancellable operating leases due in 2020			$ 2,000,000
Scenario, Forecast \| Principal executive offices
Lessee, Lease, Description [Line Items]
Office lease payments over the lease term						$ 19,000,000
Scenario, Forecast \| Houston, Texas
Lessee, Lease, Description [Line Items]
Office lease payments over the lease term							$ 4,000,000

Income Taxes - Narrative (Details) - USD ($)	12 Months Ended
Income Taxes - Narrative (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Deferred income tax benefit	$ 1,000,000
Unrecognized tax benefits	$ 0	$ 0	$ 0

Income Taxes - Schedule of Expense (Benefit) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Provision (benefit) for current income taxes
Federal	$ 0	$ 1	$ (1)
State	0	1	0
Total provision (benefit) for current income taxes	0	2	(1)
Provision (benefit) for deferred income taxes, net
Federal	(1)	(2)	3
State	0	(1)	(1)
Total provision (benefit) for deferred income taxes, net	(1)	(3)	2
Total income tax (benefit) expense	$ (1)	$ (1)	$ 1

Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Deferred tax liabilities, net:
Intercompany management fee	$ 16	$ 18
Depreciation	5	5
Accrued compensation	(16)	(17)
Total deferred tax liabilities, net	$ 5	$ 6

Equity Based Compensation - Performance Units, Restricted Units and Phantom Units (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total equity-based compensation expense	$ 16	$ 15	$ 13
Performance units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total equity-based compensation expense	9	10	9
Restricted units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total equity-based compensation expense	1	2	3
Phantom units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total equity-based compensation expense	$ 6	$ 3	$ 1
Common Units \| Long Term Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of units that may be delivered pursuant to vested awards	13,100,000

Equity Based Compensation - Performance Units (Details) - Performance units - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Award cycle	3 years
Period from change in control	2 years
Number of units granted (in units)	551,742	468,626	1,235,429
Fair value of units granted (in dollars per share)	$ 17.70	$ 19.27
Expected price volatility percentage	44.20%	47.30%
Risk-free interest rate percentage	2.36%	1.57%
Distribution yield percentage	8.56%	9.10%
Expected life of units (in years)	3 years	3 years	3 years
Awards Granted in 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Duration of daily stock price observations to determine expected price volatility	3 years
Awards Granted in 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Duration of daily stock price observations to determine expected price volatility			2 years
Average volatility period of peer group companies			1 year
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Payout percentage from target level of achievement of performance goal	0.00%
Fair value of units granted (in dollars per share)			$ 10.42
Expected price volatility percentage			43.20%
Risk-free interest rate percentage			0.86%
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Payout percentage from target level of achievement of performance goal	200.00%
Fair value of units granted (in dollars per share)			$ 27.77
Expected price volatility percentage			46.00%
Risk-free interest rate percentage			0.90%

Equity Based Compensation - Phantom Units (Details) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Restricted units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Units granted (in units)	0
Fair value of units granted (in dollars per share)	$ 0.00
Phantom units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Period from change in control	2 years
Units granted (in units)	546,708	392,338	653,286
Fair value of units granted (in dollars per share)	$ 14.23
Phantom units \| Certain Partnership Employees and Independent Directors of Enable GP \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of units granted (in dollars per share)	13.74	$ 15.44	$ 8.12
Phantom units \| Certain Partnership Employees and Independent Directors of Enable GP \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of units granted (in dollars per share)	$ 17.00	$ 16.93	$ 15.30
Other Awards \| Independent Directors Of Enable GP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Units granted (in units)	16,335	16,653	14,914
Fair value of units granted (in dollars per share)	$ 14.94	$ 15.03	$ 15.35

Equity Based Compensation - Restricted Units and Other Awards (Details) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Phantom units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Period from change in control	2 years
Units granted (in units)	546,708	392,338	653,286
Fair value of units granted (in dollars per share)	$ 14.23
Phantom units \| Certain Partnership Employees and Independent Directors of Enable GP \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of units granted (in dollars per share)	13.74	$ 15.44	$ 8.12
Phantom units \| Certain Partnership Employees and Independent Directors of Enable GP \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of units granted (in dollars per share)	$ 17.00	$ 16.93	$ 15.30
Performance units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Period from change in control	2 years
Units granted (in units)	551,742	468,626	1,235,429
Fair value of units granted (in dollars per share)	$ 17.70	$ 19.27
Expected price volatility percentage	44.20%	47.30%
Risk-free interest rate percentage	2.36%	1.57%
Performance units \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of units granted (in dollars per share)			$ 10.42
Expected price volatility percentage			43.20%
Risk-free interest rate percentage			0.86%
Performance units \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of units granted (in dollars per share)			$ 27.77
Expected price volatility percentage			46.00%
Risk-free interest rate percentage			0.90%
Restricted units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Units granted (in units)	0
Fair value of units granted (in dollars per share)	$ 0.00
Awards Granted in 2017 \| Performance units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Duration of daily stock price observations to determine expected price volatility		3 years

Equity Based Compensation - Equity Units Activity (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Performance units
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Units Outstanding at 12/31/2017 (in units)	2,040,407
Units granted (in units)	551,742	468,626	1,235,429
Vested (in units)	(401,772)
Forfeited (in units)	(80,542)
Units Outstanding at 12/31/2018 (in units)	2,109,835	2,040,407
Weighted Average Grant-Date Fair Value, Per Unit
Units Outstanding at 12/31/2017 (in dollars per share)	$ 13.86
Granted (in dollars per share)	17.70	$ 19.27
Vested (in dollars per share)	16.59
Forfeited (in dollars per share)	14.30
Units Outstanding at 12/31/2018 (in dollars per share)	$ 14.33	$ 13.86
December 31, 2018	$ 29
Aggregate intrinsic value of units vested	11	$ 5	$ 0
Fair value of units vested	$ 7	$ 10	$ 0
Performance units \| Minimum
Weighted Average Grant-Date Fair Value, Per Unit
Granted (in dollars per share)			$ 10.42
Payout percentage from target level of achievement of performance goal	0.00%
Performance units \| Maximum
Weighted Average Grant-Date Fair Value, Per Unit
Granted (in dollars per share)			$ 27.77
Payout percentage from target level of achievement of performance goal	200.00%
Restricted units
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Units Outstanding at 12/31/2017 (in units)	222,434
Units granted (in units)	0
Vested (in units)	(221,068)
Forfeited (in units)	(1,366)
Units Outstanding at 12/31/2018 (in units)	0	222,434
Weighted Average Grant-Date Fair Value, Per Unit
Units Outstanding at 12/31/2017 (in dollars per share)	$ 17.87
Granted (in dollars per share)	0.00
Vested (in dollars per share)	17.87
Forfeited (in dollars per share)	16.75
Units Outstanding at 12/31/2018 (in dollars per share)	$ 0.00	$ 17.87
December 31, 2018	$ 0
Aggregate intrinsic value of units vested	3	$ 2	$ 1
Fair value of units vested	$ 4	$ 4	$ 3
Phantom units
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Units Outstanding at 12/31/2017 (in units)	987,380
Units granted (in units)	546,708	392,338	653,286
Vested (in units)	(25,287)
Forfeited (in units)	(61,211)
Units Outstanding at 12/31/2018 (in units)	1,447,590	987,380
Weighted Average Grant-Date Fair Value, Per Unit
Units Outstanding at 12/31/2017 (in dollars per share)	$ 11.38
Granted (in dollars per share)	14.23
Vested (in dollars per share)	13.80
Forfeited (in dollars per share)	12.39
Units Outstanding at 12/31/2018 (in dollars per share)	$ 12.38	$ 11.38
December 31, 2018	$ 20
Aggregate intrinsic value of units vested	1	$ 0	$ 0
Fair value of units vested	$ 0	$ 0	$ 0
Annual Grant in 2014 \| Performance units
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Units granted (in units)	401,772
Vested (in units)	(803,544)
Weighted Average Grant-Date Fair Value, Per Unit
Payout percentage from target level of achievement of performance goal	200.00%
Annual Grant in 2015 \| Performance units
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Units granted (in units)	1,109,676
Weighted Average Grant-Date Fair Value, Per Unit
Payout percentage from target level of achievement of performance goal	100.00%
Annual Grant in 2015 \| Performance units \| Maximum
Weighted Average Grant-Date Fair Value, Per Unit
Payout percentage from target level of achievement of performance goal	200.00%
Certain Partnership Employees and Independent Directors of Enable GP \| Phantom units \| Minimum
Weighted Average Grant-Date Fair Value, Per Unit
Granted (in dollars per share)	$ 13.74	$ 15.44	$ 8.12
Certain Partnership Employees and Independent Directors of Enable GP \| Phantom units \| Maximum
Weighted Average Grant-Date Fair Value, Per Unit
Granted (in dollars per share)	$ 17.00	$ 16.93	$ 15.30

Equity Based Compensation - Unrecognized Compensation Cost (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($) shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized Compensation Cost (In millions)	$ 19
Long Term Incentive Plan \| Common Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for issuance \| shares	7,555,026
Performance units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized Compensation Cost (In millions)	$ 11
Weighted Average to be Recognized (In years)	11 months 1 day
Restricted units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized Compensation Cost (In millions)	$ 0
Weighted Average to be Recognized (In years)	0 days
Phantom units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized Compensation Cost (In millions)	$ 8
Weighted Average to be Recognized (In years)	1 year 1 month 24 days

Reportable Segments - Schedule of Financial Data for Business Segments and Services (Details)
$ in Millions

3 Months Ended

12 Months Ended

Dec. 31, 2018

USD ($)

customer

Sep. 30, 2018

USD ($)

Jun. 30, 2018

USD ($)

Mar. 31, 2018

USD ($)

Dec. 31, 2017

USD ($)

Sep. 30, 2017

USD ($)

Jun. 30, 2017

USD ($)

Mar. 31, 2017

USD ($)

Dec. 31, 2018

USD ($)

segment

customer

Dec. 31, 2017

USD ($)

Dec. 31, 2016

USD ($)

Number of reportable segments | segment

Cost of natural gas and natural gas liquids (excluding depreciation and amortization shown separately)

$ 950

^[1]

$ 928

^[1]

$ 805

^[1]

$ 748

^[1]

$ 806

^[1]

$ 705

^[1]

$ 626

^[1]

$ 666

^[1]

$ 3,431

$ 2,803

$ 2,272

484

516

444

375

445

349

279

308

1,819

1,381

1,017

Operation and maintenance, General and administrative

501

464

465

398

366

338

212

$ 171

$ 126

$ 139

129

$ 137

$ 122

$ 140

648

528

385

$ 12,444

11,593

12,444

11,593

11,212

Number of external customers | customer

$ 1,171

714

383

Operating Segments | Gathering and Processing

Cost of natural gas and natural gas liquids (excluding depreciation and amortization shown separately)

$ 2,818

2,170

1,640

1,741

1,285

915

Operation and maintenance, General and administrative

312

289

276

263

232

212

464

327

196

$ 9,874

9,079

9,874

9,079

7,453

Operating Segments | Transportation and Storage

981

601

312

Cost of natural gas and natural gas liquids (excluding depreciation and amortization shown separately)

1,162

1,146

1,024

628

604

492

Operation and maintenance, General and administrative

189

179

191

135

134

126

183

202

189

5,805

5,616

5,805

5,616

4,963

190

113

Eliminations

Cost of natural gas and natural gas liquids (excluding depreciation and amortization shown separately)

(549)

(513)

(392)

(550)

(508)

(390)

Operation and maintenance, General and administrative

(4)

(2)

(1)

$ (3,235)

$ (3,102)

(3,235)

(3,102)

(1,204)

Product

Product | Operating Segments | Gathering and Processing

2,106

1,653

1,172

Product | Operating Segments | Transportation and Storage

2,016

1,538

1,081

625

621

479

Product | Eliminations

Natural Gas, Gathering, Transportation, Marketing and Processing

(535)

(506)

(388)

Natural Gas, Gathering, Transportation, Marketing and Processing | Operating Segments | Gathering and Processing

1,325

1,150

1,100

Natural Gas, Gathering, Transportation, Marketing and Processing | Operating Segments | Transportation and Storage

802

632

559

Natural Gas, Gathering, Transportation, Marketing and Processing | Eliminations

537

525

545

Total revenue | Customer Concentration Risk

$ (14)

$ (7)

$ (4)

Effect of Fourth Quarter Events [Line Items]

10.00%

[1]	The Partnership had no external customers accounting for 10% or more of Total revenues in periods shown. See Note 15 for revenues from affiliated companies.

Quarterly Financial Data (Unaudited) - Narrative (Details) - USD ($)
$ / shares in Units, $ in Millions

3 Months Ended

12 Months Ended

Dec. 31, 2018

Sep. 30, 2018

Jun. 30, 2018

Mar. 31, 2018

Dec. 31, 2017

Sep. 30, 2017

Jun. 30, 2017

Mar. 31, 2017

Dec. 31, 2018

Dec. 31, 2017

Dec. 31, 2016

Cost of natural gas and natural gas liquids (excluding depreciation and amortization shown separately)

$ 950

^[1]

$ 928

^[1]

$ 805

^[1]

$ 748

^[1]

$ 806

^[1]

$ 705

^[1]

$ 626

^[1]

$ 666

^[1]

$ 3,431

$ 2,803

$ 2,272

484

516

444

375

445

349

279

308

1,819

1,381

1,017

Operating income (loss)

212

171

126

139

129

137

122

140

648

528

385

Net income

175

139

114

108

113

120

523

437

313

Net income attributable to limited partners

174

138

114

108

113

120

521

436

312

Net income attributable to common and subordinated units

$ 165

$ 129

$ 86

$ 105

$ 99

$ 104

$ 86

$ 111

485

400

290

Common Units

Effect of Fourth Quarter Events [Line Items]

Net income attributable to common and subordinated units

$ 485

$ 273

$ 148

$ 0.38

$ 0.30

$ 0.20

$ 0.24

$ 0.23

$ 0.24

$ 0.20

$ 0.26

$ 1.12

$ 0.92

$ 0.69

Effect of Fourth Quarter Events [Line Items]

0.38

0.30

0.20

0.24

0.23

0.24

0.20

0.26

$ 1.11

$ 0.92

$ 0.69

Subordinated Units

Net income attributable to common and subordinated units

$ 0

$ 127

$ 142

0.00

^[2]

0.00

^[2]

0.00

^[2]

0.00

^[2]

0.00

0.24

0.20

0.25

$ 0.00

$ 0.93

$ 0.68