Segment Disclosures Reconciliation of Segment Modified EBITDA to Consolidated Net Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Reconciliation of Modified EBITDA to Net Income (Loss):
Modified EBITDA Earnings (Loss)	$ 1,243	$ 1,253	$ 3,742	$ 3,552
Accretion expense associated with asset retirement obligations for nonregulated operations	(10)	(8)	(27)	(25)
Depreciation and amortization expenses	(426)	(435)	(1,285)	(1,275)
Impairment of goodwill	0	0	(187)	0
Equity earnings (losses)	106	93	236	260
Impairment of equity-method investments (Note 12)	0	(114)	(938)	(186)
Other investing income (loss) - net	2	7	6	132
Proportional Modified EBITDA of equity-method investments	(189)	(181)	(573)	(546)
Interest expense	(292)	(296)	(882)	(888)
(Provision) benefit for income taxes	(111)	(77)	(24)	(244)
Net income (loss)	323	242	68	780
Operating Segments [Member] | Transmission And Gulf Of Mexico [Member]
Reconciliation of Modified EBITDA to Net Income (Loss):
Modified EBITDA Earnings (Loss)	616	665	1,893	1,891
Operating Segments [Member] | Northeast G And P [Member]
Reconciliation of Modified EBITDA to Net Income (Loss):
Modified EBITDA Earnings (Loss)	387	345	1,126	947
Operating Segments [Member] | West [Member]
Reconciliation of Modified EBITDA to Net Income (Loss):
Modified EBITDA Earnings (Loss)	247	245	715	713
Operating Segments [Member] | Other [Member]
Reconciliation of Modified EBITDA to Net Income (Loss):
Modified EBITDA Earnings (Loss)	$ (7)	$ (2)	$ 8	$ 1