Pension, OPEB and Savings Plans (Components Of Net Periodic Benefit Cost) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service Cost	$ 142	$ 151	$ 141
Interest Cost	167	140	192
Expected Return on Plan Assets	(484)	(476)	(443)
Amortization of Prior Service Cost	0	0	(10)
Amortization of Net Actuarial Gain (Loss)	60	103	92
Non-Operating Pension and Other Postretirement Plan (Credits) Costs	(257)	(233)	(169)
Net Periodic Benefit Cost	(115)	(82)	(28)
Total Benefit Costs, Including Effect of Regulatory Asset	(115)	(82)	(28)
Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service Cost	6	9	9
Interest Cost	26	22	34
Expected Return on Plan Assets	(42)	(42)	(39)
Amortization of Prior Service Cost	(129)	(129)	(128)
Amortization of Net Actuarial Gain (Loss)	15	44	47
Non-Operating Pension and Other Postretirement Plan (Credits) Costs	(130)	(105)	(86)
Net Periodic Benefit Cost	(124)	(96)	(77)
Total Benefit Costs, Including Effect of Regulatory Asset	$ (124)	$ (96)	$ (77)