Employee Benefits - Change in Benefit Obligations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Combined Pension Plan
Change in benefit obligation
Benefit obligation at beginning of year	$ 5,212	$ 5,295	$ 9,678
Plan spin-off/ Benefit obligation transferred upon sale of business	0	0	(2,552)
Service cost	24	25	37
Interest cost	251	270	154
Actuarial (gain) loss	(119)	114	(1,432)
Benefits paid from plan assets	(552)	(494)	(590)
Special termination benefits charge	0	2	0
Benefit obligation at end of year	4,816	5,212	5,295
Post-Retirement Benefit Plans
Change in benefit obligation
Benefit obligation at beginning of year	1,919	1,995	2,781
Plan spin-off/ Benefit obligation transferred upon sale of business	0	0	(26)
Service cost	4	5	10
Interest cost	94	103	72
Participant contributions	27	32	37
Direct subsidy receipts	2	2	2
Plan amendments	0	0	(41)
Actuarial (gain) loss	(84)	14	(591)
Benefits paid by company	(214)	(228)	(249)
Benefits paid from plan assets	0	(4)	0
Special termination benefits charge	2	0	0
Benefit obligation at end of year	$ 1,750	$ 1,919	$ 1,995