Benefit Plans - Schedule of Components of Net Cost (Benefit) for Pension and Other Postretirement Plans (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Components of net periodic cost
Service cost	$ 80	$ 133	$ 102
Interest cost	239	249	229
Expected return on plan assets	(306)	(306)	(371)
Amortization of prior service credit	(1)	(21)	(52)
Costs and expenses	12	55	(92)
Remeasurement of benefit obligation	(129)	121	(1,444)
Remeasurement of plan assets	92	(112)	1,560
Remeasurement (gains) losses	(37)	9	116
Total net (benefit) cost	(25)	64	24
Pension benefits
Components of net periodic cost
Service cost	80	132	101
Interest cost	230	239	219
Expected return on plan assets	(306)	(306)	(371)
Amortization of prior service credit	0	0	(27)
Costs and expenses	4	65	(78)
Remeasurement of benefit obligation	(125)	125	(1,382)
Remeasurement of plan assets	92	(112)	1,560
Remeasurement (gains) losses	(33)	13	178
Total net (benefit) cost	(29)	78	100
Postretirement benefits
Components of net periodic cost
Service cost	0	1	1
Interest cost	9	10	10
Expected return on plan assets	0	0	0
Amortization of prior service credit	(1)	(21)	(25)
Costs and expenses	8	(10)	(14)
Remeasurement of benefit obligation	(4)	(4)	(62)
Remeasurement of plan assets	0	0	0
Remeasurement (gains) losses	(4)	(4)	(62)
Total net (benefit) cost	$ 4	$ (14)	$ (76)