Employee Benefit Plans - Components of Net Periodic Benefit Costs (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Pension Benefits Cost
Components of expense/ (income) related to net benefit expense:
Service Cost Included in Labor and Fringe	$ 8	$ 9
Interest Cost	16	14
Expected Return on Plan Assets	(47)	(46)
Amortization of Net Loss	12	18
Total Included in Other Income - Net	(19)	(14)
Net Periodic Benefit Credit	(11)	(5)
Other Post-retirement Benefits Cost
Components of expense/ (income) related to net benefit expense:
Service Cost Included in Labor and Fringe	0	0
Interest Cost	0	0
Amortization of Prior Service Credits	(1)	(1)
Total Included in Other Income - Net	(1)	(1)
Net Periodic Benefit Credit	$ (1)	$ (1)