Investment in Affiliates and Related-Party Transactions - Equity-method Investments in Affiliates (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Related Party Transaction [Line Items]
Total	$ 2,292	$ 2,099
Corporate Joint Venture | Conrail
Related Party Transaction [Line Items]
Total	1,124	1,083
Affiliated Entity
Related Party Transaction [Line Items]
Total	2,292	2,099
Affiliated Entity | TTX
Related Party Transaction [Line Items]
Total	914	849
Affiliated Entity | Other (a)
Related Party Transaction [Line Items]
Total	$ 254	$ 167