Revenues - Schedule of Revenues Disaggregated by Lines of Business (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disaggregation of Revenue [Line Items]
Revenues	$ 3,129	$ 2,743	$ 9,107	$ 8,545
Total Merchandise
Disaggregation of Revenue [Line Items]
Revenues	1,890	1,688	5,576	5,325
Chemicals
Disaggregation of Revenue [Line Items]
Revenues	596	546	1,741	1,664
Agricultural and Food Products
Disaggregation of Revenue [Line Items]
Revenues	325	288	959	941
Automotive
Disaggregation of Revenue [Line Items]
Revenues	300	269	934	892
Forest Products
Disaggregation of Revenue [Line Items]
Revenues	223	181	633	567
Metals and Equipment
Disaggregation of Revenue [Line Items]
Revenues	205	178	589	546
Minerals
Disaggregation of Revenue [Line Items]
Revenues	137	120	388	362
Fertilizers
Disaggregation of Revenue [Line Items]
Revenues	104	106	332	353
Total Coal
Disaggregation of Revenue [Line Items]
Revenues	588	514	1,660	1,566
Domestic Coal
Disaggregation of Revenue [Line Items]
Revenues	347	350	937	1,029
Export Coal
Disaggregation of Revenue [Line Items]
Revenues	241	164	723	537
Total Intermodal
Disaggregation of Revenue [Line Items]
Revenues	500	446	1,439	1,328
Domestic Intermodal
Disaggregation of Revenue [Line Items]
Revenues	331	297	948	896
International Intermodal
Disaggregation of Revenue [Line Items]
Revenues	169	149	491	432
Other
Disaggregation of Revenue [Line Items]
Revenues	$ 151	$ 95	$ 432	$ 326