Revenues - Revenues Disaggregated by Lines of Business (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Disaggregation of Revenue [Line Items]
Revenue	$ 2,855	$ 3,013	[1]
Total Merchandise
Disaggregation of Revenue [Line Items]
Revenue	1,927	1,879
Chemicals
Disaggregation of Revenue [Line Items]
Revenue	626	588
Agricultural and Food Products
Disaggregation of Revenue [Line Items]
Revenue	365	344
Automotive
Disaggregation of Revenue [Line Items]
Revenue	281	311
Forest Products
Disaggregation of Revenue [Line Items]
Revenue	217	212
Metals and Equipment
Disaggregation of Revenue [Line Items]
Revenue	199	189
Minerals
Disaggregation of Revenue [Line Items]
Revenue	127	125
Fertilizers
Disaggregation of Revenue [Line Items]
Revenue	112	110
Coal
Disaggregation of Revenue [Line Items]
Revenue	405	538
Intermodal
Disaggregation of Revenue [Line Items]
Revenue	422	428
Other
Disaggregation of Revenue [Line Items]
Revenue	$ 101	$ 168

[1] Certain prior year data has been reclassified to conform to the current presentation.