Employee Benefit Plans - Components of Net Periodic Benefit Costs (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Pension Benefits Cost
Components of expense/ (income) related to net benefit expense:
Service Cost Included in Labor and Fringe	$ 8	$ 9	$ 16	$ 18
Interest Cost	16	13	32	27
Expected Return on Plan Assets	(47)	(47)	(94)	(93)
Amortization of Net Loss	13	19	25	37
Total Included in Other Income - Net	(18)	(15)	(37)	(29)
Net Periodic Benefit Credit	(10)	(6)	(21)	(11)
Other Post-retirement Benefits Cost
Components of expense/ (income) related to net benefit expense:
Service Cost Included in Labor and Fringe	0	0	0	0
Interest Cost	1	1	1	1
Amortization of Prior Service Credits	(2)	(3)	(3)	(4)
Total Included in Other Income - Net	(1)	(2)	(2)	(3)
Net Periodic Benefit Credit	$ (1)	$ (2)	$ (2)	$ (3)