Investment in Affiliates and Related-Party Transactions - Schedule of Equity-method Investments in Affiliates (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Related Party Transaction [Line Items]
Total	$ 2,634	$ 2,520
Corporate Joint Venture | Conrail
Related Party Transaction [Line Items]
Total	1,301	1,245
Affiliated Entity
Related Party Transaction [Line Items]
Total	2,634	2,520
Affiliated Entity | TTX
Related Party Transaction [Line Items]
Total	1,055	1,012
Affiliated Entity | Other Investments in Affiliates
Related Party Transaction [Line Items]
Total	$ 278	$ 263