Revenues - Schedule of Revenues Disaggregated by Lines of Business (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Disaggregation of Revenue [Line Items]
Revenues	$ 3,102	$ 2,933	$ 5,978	$ 5,802
Total Merchandise
Disaggregation of Revenue [Line Items]
Revenues	1,907	1,798	3,686	3,637
Chemicals
Disaggregation of Revenue [Line Items]
Revenues	588	552	1,145	1,118
Automotive
Disaggregation of Revenue [Line Items]
Revenues	330	307	634	623
Agricultural and Food Products
Disaggregation of Revenue [Line Items]
Revenues	327	321	634	653
Forest Products
Disaggregation of Revenue [Line Items]
Revenues	215	194	410	386
Metals and Equipment
Disaggregation of Revenue [Line Items]
Revenues	198	178	384	368
Minerals
Disaggregation of Revenue [Line Items]
Revenues	137	128	251	242
Fertilizers
Disaggregation of Revenue [Line Items]
Revenues	112	118	228	247
Total Coal
Disaggregation of Revenue [Line Items]
Revenues	569	530	1,072	1,052
Domestic Coal
Disaggregation of Revenue [Line Items]
Revenues	317	350	590	680
Export Coal
Disaggregation of Revenue [Line Items]
Revenues	252	180	482	372
Total Intermodal
Disaggregation of Revenue [Line Items]
Revenues	490	448	939	882
Domestic Intermodal
Disaggregation of Revenue [Line Items]
Revenues	323	308	617	599
International Intermodal
Disaggregation of Revenue [Line Items]
Revenues	167	140	322	283
Other
Disaggregation of Revenue [Line Items]
Revenues	$ 136	$ 157	$ 281	$ 231