Retirement Benefits (Components Of Net Periodic Benefit Cost) (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total non-service cost components	$ (63)	$ (47)	$ (127)	$ (93)
Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service Cost	23	31	46	64
Interest cost	56	41	111	81
Defined Benefit Plan, Expected Return (Loss) on Plan Assets	(84)	(80)	(167)	(160)
Prior service benefit	0	0	0	0
Actuarial loss (gain)	(28)	6	(57)	12
Total non-service cost components	(56)	(33)	(113)	(67)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Total	(33)	(2)	$ (67)	(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	$ 6	10
Interest cost	12	9	23	17
Defined Benefit Plan, Expected Return (Loss) on Plan Assets	(23)	(22)	(46)	(43)
Prior service benefit	(1)	(1)	(2)	(2)
Actuarial loss (gain)	(12)	(5)	(23)	(9)
Total non-service cost components	(24)	(19)	(48)	(37)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Total	$ (21)	$ (14)	$ (42)	$ (27)
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