Revenues - Schedule of Revenues Disaggregated by Lines of Business (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Disaggregation of Revenue [Line Items]
Revenue	$ 3,935	$ 3,574	$ 7,417	$ 6,997
Total Merchandise
Disaggregation of Revenue [Line Items]
Revenue	2,446	2,257	4,634	4,409
Chemicals
Disaggregation of Revenue [Line Items]
Revenue	774	701	1,496	1,399
Agricultural and Food Products
Disaggregation of Revenue [Line Items]
Revenue	444	418	853	826
Automotive
Disaggregation of Revenue [Line Items]
Revenue	332	320	607	591
Forest Products
Disaggregation of Revenue [Line Items]
Revenue	266	250	495	499
Metals and Equipment
Disaggregation of Revenue [Line Items]
Revenue	256	224	476	433
Minerals
Disaggregation of Revenue [Line Items]
Revenue	242	218	434	399
Fertilizers
Disaggregation of Revenue [Line Items]
Revenue	132	126	273	262
Intermodal
Disaggregation of Revenue [Line Items]
Revenue	620	491	1,138	984
Coal
Disaggregation of Revenue [Line Items]
Revenue	520	477	978	938
Trucking
Disaggregation of Revenue [Line Items]
Revenue	226	211	428	413
Other
Disaggregation of Revenue [Line Items]
Revenue	$ 123	$ 138	$ 239	$ 253