Employee Benefit Plans - Net Benefit Expense Recorded on the Income Statement (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Components of expense/ (income) related to net benefit expense [Abstract]
Total Income Included in Other Income - Net	$ (29)	$ (79)	$ (64)
Pension Benefits
Components of expense/ (income) related to net benefit expense [Abstract]
Service Cost Included in Labor and Fringe	24	32	41
Interest Cost	111	64	55
Expected Return on Plan Assets	(164)	(188)	(186)
Amortization of Net Loss	29	50	73
Total Income Included in Other Income - Net	(24)	(74)	(58)
Net Periodic Benefit Cost (Credit)	0	(42)	(17)
Settlement Loss	0	1	0
Total Periodic Benefit Cost (Credit)	$ 0	$ (41)	$ (17)