Segment Disclosures Reconciliation of Segment Revenues to Consolidated (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment revenues
Revenues	$ 1,933	$ 1,999	$ 5,627	$ 6,094
Intersegment Elimination [Member]
Segment revenues
Revenues	(61)	(58)	(180)	(209)
Operating Segments [Member] | Transmission And Gulf Of Mexico [Member]
Segment revenues
Revenues	859	925	2,579	2,732
Operating Segments [Member] | Northeast G And P [Member]
Segment revenues
Revenues	393	384	1,138	1,082
Operating Segments [Member] | West [Member]
Segment revenues
Revenues	734	741	2,065	2,467
Operating Segments [Member] | Other [Member]
Segment revenues
Revenues	8	7	25	22
Service [Member]
Segment revenues
Revenues	1,479	1,495	4,399	4,424
Service [Member] | Transmission And Gulf Of Mexico [Member]
Segment revenues
Revenues	797	829	2,394	2,437
Service [Member] | Northeast G And P [Member]
Segment revenues
Revenues	366	340	1,052	925
Service [Member] | West [Member]
Segment revenues
Revenues	311	322	938	1,049
Service [Member] | Other [Member]
Segment revenues
Revenues	5	4	15	13
Service [Member] | Intersegment Elimination [Member]
Segment revenues
Revenues	(26)	(29)	(86)	(79)
Service [Member] | Intersegment Elimination [Member] | Transmission And Gulf Of Mexico [Member]
Segment revenues
Revenues	(10)	(13)	(37)	(36)
Service [Member] | Intersegment Elimination [Member] | Northeast G And P [Member]
Segment revenues
Revenues	(13)	(13)	(39)	(34)
Service [Member] | Intersegment Elimination [Member] | West [Member]
Segment revenues
Revenues	0	0	0	0
Service [Member] | Intersegment Elimination [Member] | Other [Member]
Segment revenues
Revenues	(3)	(3)	(10)	(9)
Service [Member] | Operating Segments [Member] | Transmission And Gulf Of Mexico [Member]
Segment revenues
Revenues	807	842	2,431	2,473
Service [Member] | Operating Segments [Member] | Northeast G And P [Member]
Segment revenues
Revenues	379	353	1,091	959
Service [Member] | Operating Segments [Member] | West [Member]
Segment revenues
Revenues	311	322	938	1,049
Service [Member] | Operating Segments [Member] | Other [Member]
Segment revenues
Revenues	8	7	25	22
NonRegulated Service Commodity Consideration [Member]
Segment revenues
Revenues	40	38	93	158
NonRegulated Service Commodity Consideration [Member] | Intersegment Elimination [Member]
Segment revenues
Revenues	0	0	0	0
NonRegulated Service Commodity Consideration [Member] | Operating Segments [Member] | Transmission And Gulf Of Mexico [Member]
Segment revenues
Revenues	6	7	14	33
NonRegulated Service Commodity Consideration [Member] | Operating Segments [Member] | Northeast G And P [Member]
Segment revenues
Revenues	2	1	5	9
NonRegulated Service Commodity Consideration [Member] | Operating Segments [Member] | West [Member]
Segment revenues
Revenues	32	30	74	116
NonRegulated Service Commodity Consideration [Member] | Operating Segments [Member] | Other [Member]
Segment revenues
Revenues	0	0	0	0
Product [Member]
Segment revenues
Revenues	414	466	1,135	1,512
Product [Member] | Transmission And Gulf Of Mexico [Member]
Segment revenues
Revenues	34	66	104	169
Product [Member] | Northeast G And P [Member]
Segment revenues
Revenues	2	22	17	87
Product [Member] | West [Member]
Segment revenues
Revenues	378	378	1,014	1,256
Product [Member] | Other [Member]
Segment revenues
Revenues	0	0	0	0
Product [Member] | Intersegment Elimination [Member]
Segment revenues
Revenues	(35)	(29)	(94)	(130)
Product [Member] | Intersegment Elimination [Member] | Transmission And Gulf Of Mexico [Member]
Segment revenues
Revenues	(12)	(10)	(30)	(57)
Product [Member] | Intersegment Elimination [Member] | Northeast G And P [Member]
Segment revenues
Revenues	(10)	(8)	(25)	(27)
Product [Member] | Intersegment Elimination [Member] | West [Member]
Segment revenues
Revenues	(13)	(11)	(39)	(46)
Product [Member] | Intersegment Elimination [Member] | Other [Member]
Segment revenues
Revenues	0	0	0	0
Product [Member] | Operating Segments [Member] | Transmission And Gulf Of Mexico [Member]
Segment revenues
Revenues	46	76	134	226
Product [Member] | Operating Segments [Member] | Northeast G And P [Member]
Segment revenues
Revenues	12	30	42	114
Product [Member] | Operating Segments [Member] | West [Member]
Segment revenues
Revenues	391	389	1,053	1,302
Product [Member] | Operating Segments [Member] | Other [Member]
Segment revenues
Revenues	$ 0	$ 0	$ 0	$ 0