Revenues - Revenues Disaggregated by Lines of Business (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Disaggregation of Revenue [Line Items]
Revenue	$ 3,013	$ 2,876
Total Merchandise
Disaggregation of Revenue [Line Items]
Revenue	1,879	1,779
Chemicals
Disaggregation of Revenue [Line Items]
Revenue	586	557
Agricultural and Food Products
Disaggregation of Revenue [Line Items]
Revenue	344	307
Automotive
Disaggregation of Revenue [Line Items]
Revenue	311	304
Forest Products
Disaggregation of Revenue [Line Items]
Revenue	216	195
Metals and Equipment
Disaggregation of Revenue [Line Items]
Revenue	189	186
Minerals
Disaggregation of Revenue [Line Items]
Revenue	123	114
Fertilizers
Disaggregation of Revenue [Line Items]
Revenue	110	116
Coal
Disaggregation of Revenue [Line Items]
Revenue	538	503
Intermodal
Disaggregation of Revenue [Line Items]
Revenue	428	449
Other
Disaggregation of Revenue [Line Items]
Revenue	$ 168	$ 145