Retirement Plans (Net Periodic Benefit Cost) (Details) - USD ($) $ in Millions	3 Months Ended				9 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Defined Benefit Plan Disclosure [Line Items]
Pension remeasurement gain				$ (91)		$ (91)
Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 12			14	$ 39	55
Interest cost on projected benefit obligation	31			22	97	71
Expected return on plan assets	(36)			(46)	(111)	(145)
Net periodic (benefit) cost	7			(10)	25	(19)
Pension settlement costs				50		50
Pension remeasurement gain				(91)		(91)
Total pension benefit cost (income)	7			(51)	25	(60)
OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	2			3	6	10
Interest cost on projected benefit obligation	8			9	23	23
Amortization of prior service credit (gain) loss recognized	(6)			(4)	(16)	(10)
Remeasurement (gains) loss	(46)	$ (12)	$ 20	(84)	(38)	(234)
Net periodic (benefit) cost	$ (42)			$ (76)	$ (25)	$ (211)