Related Parties and Affiliates - Schedule of Related Party Consolidated Balance Sheet Components (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Related Party Transaction [Line Items]
Payable to Affiliates	$ 0	$ 0
Corporate Joint Venture | Conrail | Accounts Payable
Related Party Transaction [Line Items]
Payable to Affiliates	213	153
Corporate Joint Venture | Conrail | Long-term Debt | 2.89% CSX promissory note due October 2044
Related Party Transaction [Line Items]
Promissory notes payable to Conrail subsidiary	$ 73	$ 73
Related party note, interest rate (as a percent)	2.89%	2.89%
Corporate Joint Venture | Conrail | Long-term Debt | 2.89% CSXT promissory note due October 2044
Related Party Transaction [Line Items]
Promissory notes payable to Conrail subsidiary	$ 151	$ 151
Related party note, interest rate (as a percent)	2.89%	2.89%
Affiliated Entity | TTX | Accounts Payable
Related Party Transaction [Line Items]
Payable to Affiliates	$ 34	$ 36