Revenues - Disaggregated by Lines of Business (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 30, 2016
Disaggregation of Revenue [Line Items]
Revenue	$ 3,143	$ 3,129	$ 3,102	$ 2,876	$ 2,863	$ 2,743	$ 2,933	$ 2,869	$ 12,250	$ 11,408	$ 11,069
Chemicals
Disaggregation of Revenue [Line Items]
Revenue									2,339	2,210	2,191
Agricultural and Food Products
Disaggregation of Revenue [Line Items]
Revenue									1,306	1,262	1,286
Automotive
Disaggregation of Revenue [Line Items]
Revenue									1,267	1,195	1,261
Forest Products
Disaggregation of Revenue [Line Items]
Revenue									850	755	773
Metals and Equipment
Disaggregation of Revenue [Line Items]
Revenue									769	703	704
Minerals
Disaggregation of Revenue [Line Items]
Revenue									518	477	464
Fertilizers
Disaggregation of Revenue [Line Items]
Revenue									442	466	463
Total Merchandise
Disaggregation of Revenue [Line Items]
Revenue									7,491	7,068	7,142
Coal
Disaggregation of Revenue [Line Items]
Revenue									2,246	2,107	1,833
Intermodal
Disaggregation of Revenue [Line Items]
Revenue									1,931	1,799	1,726
Other
Disaggregation of Revenue [Line Items]
Revenue									$ 582	$ 434	$ 368