Segment Disclosures Reconciliation of Segment Revenues to Consolidated (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Segment revenues
Revenues	$ 1,913	$ 2,054
Intersegment Elimination [Member]
Segment revenues
Revenues	(61)	(83)
Operating Segments [Member] | Transmission And Gulf Of Mexico [Member]
Segment revenues
Revenues	886	918
Operating Segments [Member] | Northeast G And P [Member]
Segment revenues
Revenues	389	328
Operating Segments [Member] | West [Member]
Segment revenues
Revenues	691	884
Operating Segments [Member] | Other [Member]
Segment revenues
Revenues	8	7
Service [Member]
Segment revenues
Revenues	1,474	1,440
Service [Member] | Transmission And Gulf Of Mexico [Member]
Segment revenues
Revenues	814	811
Service [Member] | Northeast G And P [Member]
Segment revenues
Revenues	344	266
Service [Member] | West [Member]
Segment revenues
Revenues	311	359
Service [Member] | Other [Member]
Segment revenues
Revenues	5	4
Service [Member] | Intersegment Elimination [Member]
Segment revenues
Revenues	(32)	(25)
Service [Member] | Intersegment Elimination [Member] | Transmission And Gulf Of Mexico [Member]
Segment revenues
Revenues	(15)	(12)
Service [Member] | Intersegment Elimination [Member] | Northeast G And P [Member]
Segment revenues
Revenues	(14)	(10)
Service [Member] | Intersegment Elimination [Member] | West [Member]
Segment revenues
Revenues	0	0
Service [Member] | Intersegment Elimination [Member] | Other [Member]
Segment revenues
Revenues	(3)	(3)
Service [Member] | Operating Segments [Member] | Transmission And Gulf Of Mexico [Member]
Segment revenues
Revenues	829	823
Service [Member] | Operating Segments [Member] | Northeast G And P [Member]
Segment revenues
Revenues	358	276
Service [Member] | Operating Segments [Member] | West [Member]
Segment revenues
Revenues	311	359
Service [Member] | Operating Segments [Member] | Other [Member]
Segment revenues
Revenues	8	7
NonRegulated Service Commodity Consideration [Member]
Segment revenues
Revenues	28	64
NonRegulated Service Commodity Consideration [Member] | Intersegment Elimination [Member]
Segment revenues
Revenues	0	0
NonRegulated Service Commodity Consideration [Member] | Operating Segments [Member] | Transmission And Gulf Of Mexico [Member]
Segment revenues
Revenues	5	13
NonRegulated Service Commodity Consideration [Member] | Operating Segments [Member] | Northeast G And P [Member]
Segment revenues
Revenues	2	5
NonRegulated Service Commodity Consideration [Member] | Operating Segments [Member] | West [Member]
Segment revenues
Revenues	21	46
NonRegulated Service Commodity Consideration [Member] | Operating Segments [Member] | Other [Member]
Segment revenues
Revenues	0	0
Product [Member]
Segment revenues
Revenues	411	550
Product [Member] | Transmission And Gulf Of Mexico [Member]
Segment revenues
Revenues	41	52
Product [Member] | Northeast G And P [Member]
Segment revenues
Revenues	23	36
Product [Member] | West [Member]
Segment revenues
Revenues	347	462
Product [Member] | Other [Member]
Segment revenues
Revenues	0	0
Product [Member] | Intersegment Elimination [Member]
Segment revenues
Revenues	(29)	(58)
Product [Member] | Intersegment Elimination [Member] | Transmission And Gulf Of Mexico [Member]
Segment revenues
Revenues	(11)	(30)
Product [Member] | Intersegment Elimination [Member] | Northeast G And P [Member]
Segment revenues
Revenues	(6)	(11)
Product [Member] | Intersegment Elimination [Member] | West [Member]
Segment revenues
Revenues	(12)	(17)
Product [Member] | Intersegment Elimination [Member] | Other [Member]
Segment revenues
Revenues	0	0
Product [Member] | Operating Segments [Member] | Transmission And Gulf Of Mexico [Member]
Segment revenues
Revenues	52	82
Product [Member] | Operating Segments [Member] | Northeast G And P [Member]
Segment revenues
Revenues	29	47
Product [Member] | Operating Segments [Member] | West [Member]
Segment revenues
Revenues	359	479
Product [Member] | Operating Segments [Member] | Other [Member]
Segment revenues
Revenues	$ 0	$ 0