Revenue from Contracts with Customers Disaggregation of Revenue (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]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 6,147	$ 5,314	$ 17,649	$ 15,749
Cargo and Freight Revenue	5,812	5,061	16,684	15,035
Total other revenues	335	253	965	714
Consumer Products [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	2,002	1,792	5,841	5,214
Industrial Products [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	1,576	1,268	4,416	3,766
Agricultural Products [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	1,165	992	3,499	3,174
Coal [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	1,069	1,009	2,928	2,881
Non-rail logistics subsidiary [Domain]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	235	163	641	458
Accessorial and other [Domain]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 100	$ 90	$ 324	$ 256