Segment Disclosures Reconciliation of Segment Modified EBITDA to Consolidated Net Income (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Reconciliation of Modified EBITDA to Net Income (Loss):
Modified EBITDA Earnings (Loss)	$ 1,306	$ 1,246	$ 2,716	$ 2,499
Accretion expense associated with asset retirement obligations for nonregulated operations	(11)	(7)	(21)	(17)
Depreciation and amortization expenses	(463)	(430)	(901)	(859)
Impairment of goodwill	0	0	0	(187)
Equity earnings (losses)	135	108	266	130
Equity Method Investment, Other than Impairment of equity-method investments	0	0	0	(938)
Other investing income (loss) - net	2	1	4	4
Proportional Modified EBITDA of equity-method investments	(230)	(192)	(455)	(384)
Interest expense	(298)	(294)	(592)	(590)
(Provision) benefit for income taxes	(119)	(117)	(260)	87
Net income (loss)	322	315	757	(255)
Operating Segments [Member] | Transmission And Gulf Of Mexico [Member]
Reconciliation of Modified EBITDA to Net Income (Loss):
Modified EBITDA Earnings (Loss)	646	615	1,306	1,277
Operating Segments [Member] | Northeast G And P [Member]
Reconciliation of Modified EBITDA to Net Income (Loss):
Modified EBITDA Earnings (Loss)	409	370	811	739
Operating Segments [Member] | West [Member]
Reconciliation of Modified EBITDA to Net Income (Loss):
Modified EBITDA Earnings (Loss)	231	253	546	468
Operating Segments [Member] | Other [Member]
Reconciliation of Modified EBITDA to Net Income (Loss):
Modified EBITDA Earnings (Loss)	$ 20	$ 8	$ 53	$ 15