Segment Disclosures Reconciliation of Segment Revenues to Consolidated (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Segment revenues
Revenue from Contract with Customer, Excluding Assessed Tax	$ 2,034	$ 2,068
Service revenues – commodity consideration	64	101
Total revenues	2,054	2,088
Intersegment Elimination [Member]
Segment revenues
Service revenues – commodity consideration	0	0
Total revenues	(83)	(110)
Operating Segments [Member] | Northeast G And P [Member]
Segment revenues
Service revenues – commodity consideration	5	4
Total revenues	328	330
Operating Segments [Member] | Atlantic Gulf [Member]
Segment revenues
Service revenues – commodity consideration	13	15
Total revenues	804	717
Operating Segments [Member] | West [Member]
Segment revenues
Service revenues – commodity consideration	46	82
Total revenues	998	1,143
Operating Segments [Member] | Other [Member]
Segment revenues
Service revenues – commodity consideration	0	0
Total revenues	7	8
Service [Member]
Segment revenues
Revenue from Contract with Customer, Excluding Assessed Tax	1,440	1,351
Service [Member] | Northeast G And P [Member]
Segment revenues
Revenue from Contract with Customer, Excluding Assessed Tax	266	219
Service [Member] | Atlantic Gulf [Member]
Segment revenues
Revenue from Contract with Customer, Excluding Assessed Tax	697	596
Service [Member] | West [Member]
Segment revenues
Revenue from Contract with Customer, Excluding Assessed Tax	473	531
Service [Member] | Other [Member]
Segment revenues
Revenue from Contract with Customer, Excluding Assessed Tax	4	5
Service [Member] | Intersegment Elimination [Member]
Segment revenues
Revenue from Contract with Customer, Excluding Assessed Tax	(25)	(25)
Service [Member] | Intersegment Elimination [Member] | Northeast G And P [Member]
Segment revenues
Revenue from Contract with Customer, Excluding Assessed Tax	10	9
Service [Member] | Intersegment Elimination [Member] | Atlantic Gulf [Member]
Segment revenues
Revenue from Contract with Customer, Excluding Assessed Tax	12	13
Service [Member] | Intersegment Elimination [Member] | West [Member]
Segment revenues
Revenue from Contract with Customer, Excluding Assessed Tax	0	0
Service [Member] | Intersegment Elimination [Member] | Other [Member]
Segment revenues
Revenue from Contract with Customer, Excluding Assessed Tax	3	3
Service [Member] | Operating Segments [Member] | Northeast G And P [Member]
Segment revenues
Revenue from Contract with Customer, Excluding Assessed Tax	276	228
Service [Member] | Operating Segments [Member] | Atlantic Gulf [Member]
Segment revenues
Revenue from Contract with Customer, Excluding Assessed Tax	709	609
Service [Member] | Operating Segments [Member] | West [Member]
Segment revenues
Revenue from Contract with Customer, Excluding Assessed Tax	473	531
Service [Member] | Operating Segments [Member] | Other [Member]
Segment revenues
Revenue from Contract with Customer, Excluding Assessed Tax	7	8
Product [Member]
Segment revenues
Revenue from Contract with Customer, Excluding Assessed Tax	550	636
Product [Member] | Northeast G And P [Member]
Segment revenues
Revenue from Contract with Customer, Excluding Assessed Tax	36	89
Product [Member] | Atlantic Gulf [Member]
Segment revenues
Revenue from Contract with Customer, Excluding Assessed Tax	52	35
Product [Member] | West [Member]
Segment revenues
Revenue from Contract with Customer, Excluding Assessed Tax	462	512
Product [Member] | Other [Member]
Segment revenues
Revenue from Contract with Customer, Excluding Assessed Tax	0	0
Product [Member] | Intersegment Elimination [Member]
Segment revenues
Revenue from Contract with Customer, Excluding Assessed Tax	(58)	(85)
Product [Member] | Intersegment Elimination [Member] | Northeast G And P [Member]
Segment revenues
Revenue from Contract with Customer, Excluding Assessed Tax	11	9
Product [Member] | Intersegment Elimination [Member] | Atlantic Gulf [Member]
Segment revenues
Revenue from Contract with Customer, Excluding Assessed Tax	30	58
Product [Member] | Intersegment Elimination [Member] | West [Member]
Segment revenues
Revenue from Contract with Customer, Excluding Assessed Tax	17	18
Product [Member] | Intersegment Elimination [Member] | Other [Member]
Segment revenues
Revenue from Contract with Customer, Excluding Assessed Tax	0	0
Product [Member] | Operating Segments [Member] | Northeast G And P [Member]
Segment revenues
Revenue from Contract with Customer, Excluding Assessed Tax	47	98
Product [Member] | Operating Segments [Member] | Atlantic Gulf [Member]
Segment revenues
Revenue from Contract with Customer, Excluding Assessed Tax	82	93
Product [Member] | Operating Segments [Member] | West [Member]
Segment revenues
Revenue from Contract with Customer, Excluding Assessed Tax	479	530
Product [Member] | Operating Segments [Member] | Other [Member]
Segment revenues
Revenue from Contract with Customer, Excluding Assessed Tax	$ 0	$ 0