Segment Disclosures Recon from Modified EBITDA to Net Income (Loss) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Service revenues	$ 8,604
Payments to Acquire Productive Assets	3,171	$ 2,814	$ 2,145
Reconciliation of Modified EBITDA to Net Income (Loss)
Modified EBITDA	3,388	3,466	3,322
Accretion expense associated with asset retirement obligations for nonregulated operations	(33)	(33)	(31)
Depreciation and amortization expenses	(1,725)	(1,736)	(1,763)
Equity earnings (losses)	396	434	397
Impairment of equity-method investments	(32)	0	(430)
Other investing income (loss) – net	219	282	63
Proportional Modified Ebitda Equity Method Investments	(770)	(795)	(754)
Interest Expense	(1,112)	(1,083)	(1,179)
(Provision) benefit for income taxes	(138)	1,974	25
Net income (loss)	193	2,509	(350)
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Payments to Acquire Productive Assets	0	0	(1)
Reconciliation of Modified EBITDA to Net Income (Loss)
Proportional Modified Ebitda Equity Method Investments	0	0	0
Operating Segments [Member] | Northeast G And P [Member]
Segment Reporting Information [Line Items]
Payments to Acquire Productive Assets	477	460	223
Reconciliation of Modified EBITDA to Net Income (Loss)
Modified EBITDA	1,086	819	853
Proportional Modified Ebitda Equity Method Investments	(493)	(452)	(357)
Operating Segments [Member] | Atlantic Gulf [Member]
Segment Reporting Information [Line Items]
Payments to Acquire Productive Assets	2,297	2,001	1,608
Reconciliation of Modified EBITDA to Net Income (Loss)
Modified EBITDA	2,023	1,238	1,621
Proportional Modified Ebitda Equity Method Investments	(183)	(264)	(287)
Operating Segments [Member] | West [Member]
Segment Reporting Information [Line Items]
Payments to Acquire Productive Assets	361	321	223
Reconciliation of Modified EBITDA to Net Income (Loss)
Modified EBITDA	308	412	1,544
Proportional Modified Ebitda Equity Method Investments	(94)	(79)	(110)
Operating Segments [Member] | Other [Member]
Segment Reporting Information [Line Items]
Payments to Acquire Productive Assets	36	32	92
Reconciliation of Modified EBITDA to Net Income (Loss)
Modified EBITDA	(29)	997	(696)
Proportional Modified Ebitda Equity Method Investments	0	0	0
Service [Member]
Segment Reporting Information [Line Items]
Service revenues	5,502	5,312	5,171
Service [Member] | Northeast G And P [Member]
Segment Reporting Information [Line Items]
Service revenues	935	837	836
Service [Member] | Atlantic Gulf [Member]
Segment Reporting Information [Line Items]
Service revenues	2,460	2,202	1,959
Service [Member] | West [Member]
Segment Reporting Information [Line Items]
Service revenues	2,085	2,246	2,328
Service [Member] | Other [Member]
Segment Reporting Information [Line Items]
Service revenues	22	27	48
Service [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Service revenues	(102)	(83)	(84)
Service [Member] | Intersegment Eliminations [Member] | Northeast G And P [Member]
Segment Reporting Information [Line Items]
Service revenues	41	35	34
Service [Member] | Intersegment Eliminations [Member] | Atlantic Gulf [Member]
Segment Reporting Information [Line Items]
Service revenues	49	37	39
Service [Member] | Intersegment Eliminations [Member] | West [Member]
Segment Reporting Information [Line Items]
Service revenues	0	0	0
Service [Member] | Intersegment Eliminations [Member] | Other [Member]
Segment Reporting Information [Line Items]
Service revenues	12	11	11
Service [Member] | Operating Segments [Member] | Northeast G And P [Member]
Segment Reporting Information [Line Items]
Service revenues	976	872	870
Service [Member] | Operating Segments [Member] | Atlantic Gulf [Member]
Segment Reporting Information [Line Items]
Service revenues	2,509	2,239	1,998
Service [Member] | Operating Segments [Member] | West [Member]
Segment Reporting Information [Line Items]
Service revenues	2,085	2,246	2,328
Service [Member] | Operating Segments [Member] | Other [Member]
Segment Reporting Information [Line Items]
Service revenues	$ 34	$ 38	$ 59