Retirement Benefits (Components Of Net Periodic Benefit Cost) (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total non-service cost components	$ (84)	$ (45)	$ (211)	$ (138)
Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service Cost	10	31	56	95
Interest cost	55	42	166	123
Defined Benefit Plan, Expected Return (Loss) on Plan Assets	(84)	(80)	(251)	(240)
Prior service benefit	0	0	0	0
Actuarial (gain) loss	(29)	7	(86)	19
Total non-service cost components	(58)	(31)	(171)	(98)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Total	(48)	0	$ (115)	(3)
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	5	$ 9	15
Interest cost	11	8	34	25
Defined Benefit Plan, Expected Return (Loss) on Plan Assets	(22)	(21)	(68)	(64)
Prior service benefit	(1)	(1)	(3)	(3)
Actuarial (gain) loss	(12)	(5)	(35)	(14)
Total non-service cost components	(24)	(19)	(72)	(56)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Total	$ (21)	$ (14)	$ (63)	$ (41)
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