Retirement Benefits (Components Of Net Periodic Benefit Cost) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total non-service cost components	$ (46)	$ (34)
Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service Cost	33	33
Interest cost	40	38
Expected return on plan assets	(80)	(75)
Prior service benefit	0	0
Actuarial loss (gain)	6	17
Total non-service cost components	(34)	(20)
Net periodic benefit cost (income)	(1)	13
Other Postretirement Benefit Plan, Defined Benefit
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service Cost	5	6
Interest cost	8	8
Expected return on plan assets	(21)	(20)
Prior service benefit	(1)	(1)
Actuarial loss (gain)	(4)	(1)
Total non-service cost components	(18)	(14)
Net periodic benefit cost (income)	$ (13)	$ (8)