Components of Deferred Tax Assets / (Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Components of Deferred Tax Assets and Liabilities [Abstract]
Deferred Tax Liabilities, Property and Equipment	$ (14,895)	$ (14,953)
Deferred Tax Liabilities, Operating Lease Right-Of-Use-Assets	(233)	(314)
Deferred Tax Liabilities, Other	(634)	(621)
Deferred Tax Liabilities, Gross	(15,762)	(15,888)
Deferred Tax Assets, Operating Lease Liabilities	232	315
Deferred Tax Assets, Compensation and Benefits	166	202
Deferred Tax Assets, Casualty and environmental	97	105
Deferred Tax Assets, Other	157	110
Total Deferred Tax Assets	652	732
Deferred Tax Liabilities, Net	$ (15,110)	$ (15,156)