Revenue from Contracts with Customers (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Revenues	$ 5,839	$ 6,021	$ 5,893	$ 5,762	$ 6,206	$ 6,147	$ 5,878	$ 5,624	$ 23,515	$ 23,855	$ 21,387
Non-rail logistics subsidiary									770	856	640
Accessorial and other									417	421	341
Total other revenues									1,187	1,277	981
Accounts receivable, after allowance for credit loss	1,100				1,300				1,100	1,300
Revenue, remaining performance obligation, amount	$ 175				$ 237				175	237
Consumer Products
Disaggregation of Revenue [Line Items]
Revenues									7,860	7,902	7,111
Industrial Products
Disaggregation of Revenue [Line Items]
Revenues									6,068	5,967	5,133
Agricultural Products
Disaggregation of Revenue [Line Items]
Revenues									4,685	4,697	4,316
Coal
Disaggregation of Revenue [Line Items]
Revenues									3,715	4,012	3,846
Total freight revenues
Disaggregation of Revenue [Line Items]
Revenues									$ 22,328	$ 22,578	$ 20,406