Segment Disclosures Reconciliation of Segment Revenues to Consolidated (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Segment revenues
Revenues	$ 1,781	$ 2,041	$ 3,694	$ 4,095
Intersegment Elimination [Member]
Segment revenues
Revenues	(58)	(68)	(119)	(151)
Operating Segments [Member] | Transmission And Gulf Of Mexico [Member]
Segment revenues
Revenues	834	889	1,720	1,807
Operating Segments [Member] | Northeast G And P [Member]
Segment revenues
Revenues	356	370	745	698
Operating Segments [Member] | West [Member]
Segment revenues
Revenues	640	842	1,331	1,726
Operating Segments [Member] | Other [Member]
Segment revenues
Revenues	9	8	17	15
Service [Member]
Segment revenues
Revenues	1,446	1,489	2,920	2,929
Service [Member] | Transmission And Gulf Of Mexico [Member]
Segment revenues
Revenues	783	797	1,597	1,608
Service [Member] | Northeast G And P [Member]
Segment revenues
Revenues	342	319	686	585
Service [Member] | West [Member]
Segment revenues
Revenues	316	368	627	727
Service [Member] | Other [Member]
Segment revenues
Revenues	5	5	10	9
Service [Member] | Intersegment Elimination [Member]
Segment revenues
Revenues	(28)	(25)	(60)	(50)
Service [Member] | Intersegment Elimination [Member] | Transmission And Gulf Of Mexico [Member]
Segment revenues
Revenues	(12)	(11)	(27)	(23)
Service [Member] | Intersegment Elimination [Member] | Northeast G And P [Member]
Segment revenues
Revenues	(12)	(11)	(26)	(21)
Service [Member] | Intersegment Elimination [Member] | West [Member]
Segment revenues
Revenues	0	0	0	0
Service [Member] | Intersegment Elimination [Member] | Other [Member]
Segment revenues
Revenues	(4)	(3)	(7)	(6)
Service [Member] | Operating Segments [Member] | Transmission And Gulf Of Mexico [Member]
Segment revenues
Revenues	795	808	1,624	1,631
Service [Member] | Operating Segments [Member] | Northeast G And P [Member]
Segment revenues
Revenues	354	330	712	606
Service [Member] | Operating Segments [Member] | West [Member]
Segment revenues
Revenues	316	368	627	727
Service [Member] | Operating Segments [Member] | Other [Member]
Segment revenues
Revenues	9	8	17	15
NonRegulated Service Commodity Consideration [Member]
Segment revenues
Revenues	25	56	53	120
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	3	13	8	26
NonRegulated Service Commodity Consideration [Member] | Operating Segments [Member] | Northeast G And P [Member]
Segment revenues
Revenues	1	3	3	8
NonRegulated Service Commodity Consideration [Member] | Operating Segments [Member] | West [Member]
Segment revenues
Revenues	21	40	42	86
NonRegulated Service Commodity Consideration [Member] | Operating Segments [Member] | Other [Member]
Segment revenues
Revenues	0	0	0	0
Product [Member]
Segment revenues
Revenues	310	496	721	1,046
Product [Member] | Transmission And Gulf Of Mexico [Member]
Segment revenues
Revenues	29	51	70	103
Product [Member] | Northeast G And P [Member]
Segment revenues
Revenues	(8)	29	15	65
Product [Member] | West [Member]
Segment revenues
Revenues	289	416	636	878
Product [Member] | Other [Member]
Segment revenues
Revenues	0	0	0	0
Product [Member] | Intersegment Elimination [Member]
Segment revenues
Revenues	(30)	(43)	(59)	(101)
Product [Member] | Intersegment Elimination [Member] | Transmission And Gulf Of Mexico [Member]
Segment revenues
Revenues	(7)	(17)	(18)	(47)
Product [Member] | Intersegment Elimination [Member] | Northeast G And P [Member]
Segment revenues
Revenues	(9)	(8)	(15)	(19)
Product [Member] | Intersegment Elimination [Member] | West [Member]
Segment revenues
Revenues	(14)	(18)	(26)	(35)
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	36	68	88	150
Product [Member] | Operating Segments [Member] | Northeast G And P [Member]
Segment revenues
Revenues	1	37	30	84
Product [Member] | Operating Segments [Member] | West [Member]
Segment revenues
Revenues	303	434	662	913
Product [Member] | Operating Segments [Member] | Other [Member]
Segment revenues
Revenues	$ 0	$ 0	$ 0	$ 0