Nature of Operations and Significant Accounting Policies - Narrative (Details) mi in Thousands, carload in Thousands, unit in Millions, $ in Millions		12 Months Ended
		Dec. 31, 2024 USD ($) employee terminal railroad state port_terminal mi	Dec. 31, 2024 employee terminal railroad line_of_business state port_terminal mi	Dec. 31, 2024 employee terminal railroad carload state port_terminal mi	Dec. 31, 2024 employee terminal railroad state port_terminal mi	Dec. 31, 2024 employee unit terminal railroad state port_terminal mi	Dec. 31, 2024 employee terminal railroad state operatingSegment port_terminal mi	Dec. 31, 2024 employee terminal railroad state port_terminal mi	Dec. 31, 2024 employee terminal railroad segment state port_terminal mi	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Revenue from External Customer [Line Items]
Number of rail route miles | mi		20	20	20	20	20	20	20	20
Rail network states number | state		26	26	26	26	26	26	26	26
Number of ocean, river and lake ports serviced (over) | port_terminal		70	70	70	70	70	70	70	70
Number of short-line and regional railroads served (more than) | railroad		240	240	240	240	240	240	240	240
Revenue	[1]	$ 14,540								$ 14,657	$ 14,853
Number of primary lines of business | line_of_business			4
Number of operating segments							2		2
Number of employees (more than) | employee		23,500	23,500	23,500	23,500	23,500	23,500	23,500	23,500
Number of union employees | employee								17,500
Cost method, maximum percentage					20.00%
Merchandise business
Revenue from External Customer [Line Items]
Revenue		$ 8,903								8,653	8,239
Number of carloads | carload				2,600
Percentage of total volume					42.00%
Percentage of total revenue					61.00%
Intermodal business
Revenue from External Customer [Line Items]
Revenue		$ 2,047								2,060	2,306
Number of carloads | carload				736
Percentage of total volume					46.00%
Percentage of total revenue					14.00%
Number of terminals | terminal		30	30	30	30	30	30	30	30
Coal business
Revenue from External Customer [Line Items]
Revenue		$ 2,247								2,484	2,434
Number of carloads | unit						2.9
Percentage of total volume					12.00%
Percentage of total revenue					15.00%
Trucking business
Revenue from External Customer [Line Items]
Revenue		844								882	966
Percentage of total revenue					6.00%
Other
Revenue from External Customer [Line Items]
Revenue		$ 499								$ 578	$ 908
Percentage of total revenue					4.00%

[1] See Note 20, Revision of Prior Period Financial Statements