Retirement Plans (Net Periodic Benefit Cost) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Defined Benefit Plan Disclosure [Line Items]
Pension remeasurement gain	$ (44)	$ (74)
OPEB remeasurement (gain) loss	8	(9)
Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	11	12
Interest cost on projected benefit obligation	32	30
Expected return on plan assets	(38)	(42)
Pension remeasurement gain	(44)	(74)
Net periodic pension benefit cost (income)	(39)	(74)
Special termination benefits		6
Total pension benefit cost (income)	(39)	(68)
OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	1
Interest cost on projected benefit obligation	7	7
Amortization of prior service credit gain recognized	(6)	(6)
OPEB remeasurement (gain) loss	8	(9)
Net periodic pension benefit cost (income)	10	(7)
Special termination benefits		1
Total pension benefit cost (income)	$ 10	$ (6)