Retirement Benefits (Components Of Net Periodic Benefit Cost) (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total non-service cost components	$ (76)	$ (84)	$ (228)	$ (211)
Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service Cost	22	10	66	56
Interest cost	56	55	167	166
Defined Benefit Plan, Expected Return (Loss) on Plan Assets	(82)	(84)	(246)	(251)
Prior service benefit	0	0	0	0
Actuarial (gain)	(17)	(29)	(50)	(86)
Total non-service cost components	(43)	(58)	(129)	(171)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Total	(21)	(48)	$ (63)	(115)
Defined Benefit Plan, Amortization Period of Actuarial Gain (Loss)			10 years
Defined Benefit Plan, Difference Between Actual and Expected Return (Loss) on Plan Assets Amortization Period			4 years
Other Postretirement Benefit Plan, Defined Benefit
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service Cost	3	3	$ 9	9
Interest cost	11	11	33	34
Defined Benefit Plan, Expected Return (Loss) on Plan Assets	(23)	(22)	(69)	(68)
Prior service benefit	(1)	(1)	(3)	(3)
Actuarial (gain)	(9)	(12)	(29)	(35)
Total non-service cost components	(22)	(24)	(68)	(72)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Total	$ (19)	$ (21)	$ (59)	$ (63)
Defined Benefit Plan, Amortization Period of Actuarial Gain (Loss)			10 years
Defined Benefit Plan, Difference Between Actual and Expected Return (Loss) on Plan Assets Amortization Period			4 years