Revenue Recognition Revenue by Category (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		$ 1,985	$ 2,280	$ 6,040	$ 6,423
Revenue Not from Contract with Customer	[1]	14	23	54	59
Total revenues		1,999	2,303	6,094	6,482
NonRegulated Service Monetary Consideration [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		716	749	2,159	2,208
NonRegulated Service Commodity Consideration [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		38	121	158	316
Total revenues		38	121	158	316
Regulated Service [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		710	566	2,067	1,696
Other Service [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		53	34	146	103
Service [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		1,517	1,470	4,530	4,323
Total revenues		1,495	1,371	4,424	4,062
NGL And Natural Gas Product Sales [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		468	801	1,510	2,084
Other Product Sales [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax			9		16
Total Product Sales [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax			810		2,100
Total revenues		466	811	1,512	2,104
Northeast Midstream [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		379	316	1,067	947
Revenue Not from Contract with Customer	[1]	5	6	15	16
Total revenues		384	322	1,082	963
Northeast Midstream [Member] | NonRegulated Service Monetary Consideration [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		310	219	840	626
Northeast Midstream [Member] | NonRegulated Service Commodity Consideration [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		1	5	9	14
Northeast Midstream [Member] | Regulated Service [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		0	0	0	0
Northeast Midstream [Member] | Other Service [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		38	23	104	65
Northeast Midstream [Member] | Service [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		349	247	953	705
Northeast Midstream [Member] | NGL And Natural Gas Product Sales [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		30	69	114	242
Northeast Midstream [Member] | Other Product Sales [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax			0		0
Northeast Midstream [Member] | Total Product Sales [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax			69		242
Atlantic Gulf Midstream [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		166	250	560	693
Revenue Not from Contract with Customer	[1]	2	5	6	14
Total revenues		168	255	566	707
Atlantic Gulf Midstream [Member] | NonRegulated Service Monetary Consideration [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		117	139	366	404
Atlantic Gulf Midstream [Member] | NonRegulated Service Commodity Consideration [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		7	19	33	45
Atlantic Gulf Midstream [Member] | Regulated Service [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		0	0	0	0
Atlantic Gulf Midstream [Member] | Other Service [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		8	4	21	12
Atlantic Gulf Midstream [Member] | Service [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		132	162	420	461
Atlantic Gulf Midstream [Member] | NGL And Natural Gas Product Sales [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		34	88	140	232
Atlantic Gulf Midstream [Member] | Other Product Sales [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax			0		0
Atlantic Gulf Midstream [Member] | Total Product Sales [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax			88		232
West Midstream [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		741	1,249	2,455	3,342
Revenue Not from Contract with Customer	[1]	0	3	12	6
Total revenues		741	1,252	2,467	3,348
West Midstream [Member] | NonRegulated Service Monetary Consideration [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		308	409	1,007	1,231
West Midstream [Member] | NonRegulated Service Commodity Consideration [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		30	97	116	257
West Midstream [Member] | Regulated Service [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		0	0	0	0
West Midstream [Member] | Other Service [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		12	11	32	35
West Midstream [Member] | Service [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		350	517	1,155	1,523
West Midstream [Member] | NGL And Natural Gas Product Sales [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		391	720	1,300	1,799
West Midstream [Member] | Other Product Sales [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax			12		20
West Midstream [Member] | Total Product Sales [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax			732		1,819
Transco [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		642	498	1,825	1,465
Revenue Not from Contract with Customer	[1]	3	3	8	8
Total revenues		645	501	1,833	1,473
Transco [Member] | NonRegulated Service Monetary Consideration [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		0	0	0	0
Transco [Member] | NonRegulated Service Commodity Consideration [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		0	0	0	0
Transco [Member] | Regulated Service [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		601	457	1,736	1,368
Transco [Member] | Other Service [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		0	0	1	1
Transco [Member] | Service [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		601	457	1,737	1,369
Transco [Member] | NGL And Natural Gas Product Sales [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		41	41	88	96
Transco [Member] | Other Product Sales [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax			0		0
Transco [Member] | Total Product Sales [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax			41		96
Northwest Pipeline [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		111	110	335	330
Revenue Not from Contract with Customer	[1]	0	0	0	0
Total revenues		111	110	335	330
Northwest Pipeline [Member] | NonRegulated Service Monetary Consideration [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		0	0	0	0
Northwest Pipeline [Member] | NonRegulated Service Commodity Consideration [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		0	0	0	0
Northwest Pipeline [Member] | Regulated Service [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		111	110	335	330
Northwest Pipeline [Member] | Other Service [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		0	0	0	0
Northwest Pipeline [Member] | Service [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		111	110	335	330
Northwest Pipeline [Member] | NGL And Natural Gas Product Sales [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		0	0	0	0
Northwest Pipeline [Member] | Other Product Sales [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax			0		0
Northwest Pipeline [Member] | Total Product Sales [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax			0		0
Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		0	1	0	2
Revenue Not from Contract with Customer	[1]	7	9	22	24
Total revenues		7	10	22	26
Other [Member] | NonRegulated Service Monetary Consideration [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		0	1	0	2
Other [Member] | NonRegulated Service Commodity Consideration [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		0	0	0	0
Other [Member] | Regulated Service [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		0	0	0	0
Other [Member] | Other Service [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		0	0	0	0
Other [Member] | Service [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		0	1	0	2
Other [Member] | NGL And Natural Gas Product Sales [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		0	0	0	0
Other [Member] | Other Product Sales [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax			0		0
Other [Member] | Total Product Sales [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax			0		0
Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		(54)	(144)	(202)	(356)
Revenue Not from Contract with Customer	[1]	(3)	(3)	(9)	(9)
Total revenues		(57)	(147)	(211)	(365)
Intersegment Eliminations [Member] | NonRegulated Service Monetary Consideration [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		(19)	(19)	(54)	(55)
Intersegment Eliminations [Member] | NonRegulated Service Commodity Consideration [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		0	0	0	0
Intersegment Eliminations [Member] | Regulated Service [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		(2)	(1)	(4)	(2)
Intersegment Eliminations [Member] | Other Service [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		(5)	(4)	(12)	(10)
Intersegment Eliminations [Member] | Service [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		(26)	(24)	(70)	(67)
Intersegment Eliminations [Member] | NGL And Natural Gas Product Sales [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		$ (28)	(117)	$ (132)	(285)
Intersegment Eliminations [Member] | Other Product Sales [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax			(3)		(4)
Intersegment Eliminations [Member] | Total Product Sales [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax			$ (120)		$ (289)

[1] Revenues not within the scope of ASC 606, “Revenue from Contracts with Customers,” consist of leasing revenues associated with our headquarters building and management fees that we receive for certain services we provide to operated equity-method investments, which are reported in Service revenues in our Consolidated Statement of Income, and amounts associated with our derivative contracts, which are reported in Product sales in our Consolidated Statement of Income.