Properties - Narrative (Details) $ in Millions		3 Months Ended		6 Months Ended	9 Months Ended	12 Months Ended						21 Months Ended
		Mar. 31, 2024 USD ($)	Mar. 31, 2023 USD ($)	Jun. 30, 2023 USD ($)	Sep. 30, 2023 USD ($)	Dec. 31, 2024 USD ($)		Dec. 31, 2023 USD ($)		Dec. 31, 2022 USD ($)		Dec. 31, 2022 USD ($)	Mar. 26, 2021 phase property
Property, Plant and Equipment [Line Items]
Percentage of labor costs relating to the deconstruction of old track						20.00%
Percentage of labor costs relating to the installation of new track						80.00%
Percentage of assets depreciated under the group-life method						86.00%
Properties		$ 50,617	$ 48,780	$ 49,241	$ 49,691	$ 52,191		$ 50,281	[1]	$ 48,463		$ 48,463
Gains on sale of properties						11		34		238
Proceeds from property sale transaction		$ 11	$ 17	$ 52	$ 65	66	[2]	88	[2]	294	[2]
Gain (loss) on disposition of property plant equipment	[2],[3]					11		34		238
Impairment expense						$ 24		$ 2		4
Government Assistance, Asset, Increase, Statement of Financial Position [Extensible Enumeration]						Properties		Properties
Government assistance, asset, increase						$ 246		$ 84
Non-freight accounts receivable						39		57
Equipment assets
Property, Plant and Equipment [Line Items]
Properties						$ 11,162		10,643
Life studies, frequency period						3 years
Equipment assets | Service Life, Salvage Value And Other
Property, Plant and Equipment [Line Items]
Depreciation expense										80
Road and track assets
Property, Plant and Equipment [Line Items]
Properties						$ 37,684		$ 36,551
Life studies, frequency period						6 years
Virginia Line Segments
Property, Plant and Equipment [Line Items]
Number of property rights for sale | property													3
Number phases to complete property right sale transaction | phase													3
Proceeds from property sale transaction										125		525
Gain (loss) on disposition of property plant equipment										$ 144		$ 493

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

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

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