Pension And OPEB (Components Of Net Periodic Benefit Cost) (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service Cost	$ 35	$ 37	$ 106	$ 113
Interest Cost	42	35	125	105
Expected Return on Plan Assets	(120)	(119)	(362)	(357)
Amortization of Prior Service Cost	0	0	0	0
Amortization of Actuarial Loss	15	26	45	77
Non-Operating Pension and OPEB (Credits) Costs	(63)	(58)	(192)	(175)
Total Benefit (Credits) Costs	(28)	(21)	(86)	(62)
OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Service Cost	2	3	5	7
Interest Cost	6	5	19	16
Expected Return on Plan Assets	(11)	(10)	(32)	(31)
Amortization of Prior Service Cost	(32)	(33)	(96)	(97)
Amortization of Actuarial Loss	4	11	11	33
Non-Operating Pension and OPEB (Credits) Costs	(33)	(27)	(98)	(79)
Total Benefit (Credits) Costs	$ (31)	$ (24)	$ (93)	$ (72)