Employee Benefits - Change in Benefit Obligations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Combined Pension Plan
Change in benefit obligation
Benefit obligation at beginning of year	$ 9,678	$ 12,202	$ 12,217
Plan spin-off/ Benefit obligation transferred upon sale of business	(2,552)	0	0
Service cost	37	56	59
Interest cost	154	201	324
Plan amendments	0	(13)	(3)
Special termination benefits charge	0	6	13
Actuarial (gain) loss	(1,432)	(337)	749
Benefits paid from plan assets	(590)	(766)	(1,157)
Settlement payments and annuity purchase	0	(1,671)	0
Benefit obligation at end of year	5,295	9,678	12,202
Post-Retirement Benefit Plans
Change in benefit obligation
Benefit obligation at beginning of year	2,781	3,048	3,037
Plan spin-off/ Benefit obligation transferred upon sale of business	(26)	0	0
Service cost	10	14	14
Interest cost	72	47	69
Participant contributions	37	41	46
Direct subsidy receipts	2	3	6
Plan amendments	(41)	0	0
Actuarial (gain) loss	(591)	(125)	134
Curtailment loss	0	0	4
Benefits paid by company	(249)	(247)	(255)
Benefits paid from plan assets	0	0	(7)
Benefit obligation at end of year	$ 1,995	$ 2,781	$ 3,048