Employee Benefit Plans - Schedule of Net Benefit Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Components of expense/ (income) related to net benefit expense [Abstract]
Total Income Included in Other Income - Net	$ (43)	$ (38)	$ (32)
Restructuring Charge - Non Operating			56
Pension Benefits
Components of expense/ (income) related to net benefit expense [Abstract]
Service Cost Included in Labor and Fringe	31	32	36
Interest Cost	103	92	92
Expected Return on Plan Assets	(171)	(176)	(171)
Amortization of Net Loss	30	41	41
Amortization of Prior Service Cost	0	0	0
Total Income Included in Other Income - Net	(38)	(43)	(38)
Net Periodic Benefit (Credit) Expense	(7)	(11)	(2)
Restructuring Charge - Non Operating	0	0	60
Settlement (Gain) Loss	0	(1)	11
Total (Credit) Expense	(7)	(12)	69
Post-retirement Benefits
Components of expense/ (income) related to net benefit expense [Abstract]
Service Cost Included in Labor and Fringe	1	2	2
Interest Cost	2	7	7
Expected Return on Plan Assets	0	0	0
Amortization of Net Loss	0	0	0
Amortization of Prior Service Cost	(7)	(2)	0
Total Income Included in Other Income - Net	(5)	5	7
Net Periodic Benefit (Credit) Expense	(4)	7	9
Restructuring Charge - Non Operating	0	0	13
Settlement (Gain) Loss	0	0	0
Total (Credit) Expense	$ (4)	$ 7	$ 22