Segment Disclosures Reconciliation of Segment Modified EBITDA to Consolidated Net Income (Details) - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Reconciliation of Modified EBITDA to Net Income (Loss):
Modified EBITDA Earnings (Loss)	$ 1,246		$ 1,112	$ 2,499	$ 2,299
Accretion expense associated with asset retirement obligations for nonregulated operations	(7)		(8)	(17)	(17)
Depreciation and amortization expenses	(430)		(424)	(859)	(840)
Impairment of goodwill	0	$ (187)	0	(187)	0
Equity earnings (losses)	108		87	130	167
Impairment of equity-method investments	0		(2)	938	72
Other investing income (loss) - net	1		124	4	125
Proportional Modified EBITDA of equity-method investments	(192)		(175)	(384)	(365)
Interest expense	(294)		(296)	(590)	(592)
(Provision) benefit for income taxes	(117)		(98)	87	(167)
Net income (loss)	315		324	(255)	538
Operating Segments [Member] | Transmission And Gulf Of Mexico [Member]
Reconciliation of Modified EBITDA to Net Income (Loss):
Modified EBITDA Earnings (Loss)	615		590	1,277	1,226
Operating Segments [Member] | Northeast G And P [Member]
Reconciliation of Modified EBITDA to Net Income (Loss):
Modified EBITDA Earnings (Loss)	370		303	739	602
Operating Segments [Member] | West [Member]
Reconciliation of Modified EBITDA to Net Income (Loss):
Modified EBITDA Earnings (Loss)	253		212	468	468
Operating Segments [Member] | Other [Member]
Reconciliation of Modified EBITDA to Net Income (Loss):
Modified EBITDA Earnings (Loss)	$ 8		$ 7	$ 15	$ 3