Related Parties and Affiliates - Schedule of Related Party Consolidated Balance Sheet Components (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Related Party Transaction [Line Items]
Payable to Affiliates	$ 0	$ 0
Corporate Joint Venture | Accounts Payable
Related Party Transaction [Line Items]
Payable to Affiliates	153	123
Corporate Joint Venture | 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%
Corporate Joint Venture | 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%
TTX Company | Accounts Payable
Related Party Transaction [Line Items]
Payable to Affiliates	$ 36	$ 43