Investment in Affiliates and Related-Party Transactions - Equity-method Investments in Affiliates (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Related Party Transaction [Line Items]
Total	$ 2,397	$ 2,292
Corporate Joint Venture | Conrail
Related Party Transaction [Line Items]
Total	1,175	1,124
Affiliated Entity
Related Party Transaction [Line Items]
Total	2,397	2,292
Affiliated Entity | TTX
Related Party Transaction [Line Items]
Total	961	914
Affiliated Entity | Oher Equity Method and Cost Method Investments
Related Party Transaction [Line Items]
Total	$ 261	$ 254