Segment Disclosures Recon from Segment to Consolidated - Revenues (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment revenues [Line Items]
Service revenues	$ 5,173	$ 5,135	$ 3,888
Product sales	2,318	2,196	3,521
Total revenues	7,491	7,331	7,409
Other financial information:
Proportional Modified EBITDA of equity-method investments	754	699	431
Intersegment Eliminations [Member]
Segment revenues [Line Items]
Service revenues	(60)	(37)	(17)
Product sales	(674)	(572)	(1,094)
Total revenues	(734)	(609)	(1,111)
Other financial information:
Proportional Modified EBITDA of equity-method investments	0	15	7
Central [Member]
Segment revenues [Line Items]
Service revenues	1,228	1,261	666
Product sales	0	0	0
Central [Member] | Intersegment Eliminations [Member]
Segment revenues [Line Items]
Service revenues	(13)	(26)	(12)
Product sales	0	0	0
Central [Member] | Operating Segments [Member]
Segment revenues [Line Items]
Service revenues	1,241	1,287	678
Product sales	0	0	0
Total revenues	1,241	1,287	678
Other financial information:
Proportional Modified EBITDA of equity-method investments	48	36	25
Northeast G&P [Member]
Segment revenues [Line Items]
Service revenues	804	803	549
Product sales	135	109	225
Northeast G&P [Member] | Intersegment Eliminations [Member]
Segment revenues [Line Items]
Service revenues	(34)	(7)	(1)
Product sales	(28)	(18)	(5)
Northeast G&P [Member] | Operating Segments [Member]
Segment revenues [Line Items]
Service revenues	838	810	550
Product sales	163	127	230
Total revenues	1,001	937	780
Other financial information:
Proportional Modified EBITDA of equity-method investments	362	349	198
Atlantic Gulf [Member]
Segment revenues [Line Items]
Service revenues	1,939	1,877	1,497
Product sales	244	287	499
Atlantic Gulf [Member] | Intersegment Eliminations [Member]
Segment revenues [Line Items]
Service revenues	(13)	(4)	(4)
Product sales	(205)	(176)	(354)
Atlantic Gulf [Member] | Operating Segments [Member]
Segment revenues [Line Items]
Service revenues	1,952	1,881	1,501
Product sales	449	463	853
Total revenues	2,401	2,344	2,354
Other financial information:
Proportional Modified EBITDA of equity-method investments	287	257	151
West [Member]
Segment revenues [Line Items]
Service revenues	1,034	1,055	1,050
Product sales	18	36	70
West [Member] | Intersegment Eliminations [Member]
Segment revenues [Line Items]
Service revenues	0	0	0
Product sales	(260)	(221)	(476)
West [Member] | Operating Segments [Member]
Segment revenues [Line Items]
Service revenues	1,034	1,055	1,050
Product sales	278	257	546
Total revenues	1,312	1,312	1,596
Other financial information:
Proportional Modified EBITDA of equity-method investments	0	0	0
NGL And Petchem Services [Member]
Segment revenues [Line Items]
Service revenues	168	139	126
Product sales	1,921	1,764	2,727
NGL And Petchem Services [Member] | Intersegment Eliminations [Member]
Segment revenues [Line Items]
Service revenues	0	0	0
Product sales	(181)	(157)	(259)
NGL And Petchem Services [Member] | Operating Segments [Member]
Segment revenues [Line Items]
Service revenues	168	139	126
Product sales	2,102	1,921	2,986
Total revenues	2,270	2,060	3,112
Other financial information:
Proportional Modified EBITDA of equity-method investments	$ 57	$ 42	$ 50