Employee Benefit Plans, Pre-Tax Amounts in Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Pension Plans [Member]
Pension and Other Postretirement Benefit Plans Accumulated Other Comprehensive Loss, before Tax
Net actuarial (gain) loss	$ 256	$ 342
Prior service cost (credit)	11	(25)
Total	267	317
Other Postretirement Benefit Plans [Member]
Pension and Other Postretirement Benefit Plans Accumulated Other Comprehensive Loss, before Tax
Net actuarial (gain) loss	(73)	(89)
Prior service cost (credit)	2	(2)
Total	$ (71)	$ (91)