Segment Reporting and Significant Expenses- Schedule of Segment Reporting Information (Details) - USD ($)		3 Months Ended						6 Months Ended	9 Months Ended	12 Months Ended
		Dec. 31, 2024	Mar. 31, 2024	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2023	Sep. 30, 2023	Dec. 31, 2024		Dec. 31, 2023		Dec. 31, 2022
Segment Reporting, Asset Reconciling Item [Line Items]
Revenue	[1]									$ 14,540,000,000		$ 14,657,000,000		$ 14,853,000,000
Labor and Fringe			$ 805,000,000	$ 814,000,000	$ 761,000,000	$ 748,000,000	$ 729,000,000	$ 1,477,000,000	$ 2,238,000,000	3,165,000,000	[1]	3,052,000,000	[1]	2,885,000,000	[1]
Purchased Services and Other			721,000,000	714,000,000	700,000,000	691,000,000	697,000,000	1,388,000,000	2,088,000,000	2,852,000,000	[1]	2,802,000,000	[1]	2,728,000,000	[1]
Depreciation and Amortization				405,000,000	403,000,000	404,000,000	395,000,000	799,000,000	1,202,000,000	1,658,000,000	[1],[2]	1,607,000,000	[1],[2]	1,502,000,000	[1],[2]
Fuel	[1]									1,168,000,000		1,377,000,000		1,626,000,000
Equipment and Other Rents	[1]									355,000,000		354,000,000		396,000,000
Gains on Property Dispositions	[1],[2]									(11,000,000)		(34,000,000)		(238,000,000)
Operating Income			1,337,000,000	1,315,000,000	1,271,000,000	1,466,000,000	1,447,000,000	2,913,000,000	4,184,000,000	5,245,000,000	[1]	5,499,000,000	[1]	5,954,000,000	[1]
Expenses			$ 2,344,000,000	$ 2,365,000,000	$ 2,301,000,000	$ 2,233,000,000	$ 2,259,000,000	$ 4,492,000,000	$ 6,793,000,000	9,295,000,000	[1]	9,158,000,000	[1]	8,899,000,000	[1]
Impairment	[1],[2]									108,000,000		0		0
Quality Carriers, Inc.
Segment Reporting, Asset Reconciling Item [Line Items]
Impairment												0
Operating Segments
Segment Reporting, Asset Reconciling Item [Line Items]
Operating Income										5,346,000,000		5,467,000,000		5,902,000,000
Eliminations
Segment Reporting, Asset Reconciling Item [Line Items]
Revenue										(7,000,000)		(5,000,000)		(2,000,000)
Expenses										(7,000,000)		(5,000,000)		(2,000,000)
Trucking Operating Segment | Quality Carriers, Inc.
Segment Reporting, Asset Reconciling Item [Line Items]
Impairment		$ 108,000,000								108,000,000
Trucking Operating Segment | Operating Segments
Segment Reporting, Asset Reconciling Item [Line Items]
Revenue										851,000,000		887,000,000		968,000,000
Expenses										952,000,000		855,000,000		916,000,000
Trucking Operating Segment | Eliminations
Segment Reporting, Asset Reconciling Item [Line Items]
Revenue										844,000,000		882,000,000		966,000,000
Expenses										945,000,000		850,000,000		914,000,000
Rail Operations
Segment Reporting, Asset Reconciling Item [Line Items]
Impairment		$ 0
Rail Operations | Operating Segments
Segment Reporting, Asset Reconciling Item [Line Items]
Revenue										13,696,000,000		13,775,000,000		13,887,000,000
Labor and Fringe										2,971,000,000		2,875,000,000		2,723,000,000
Purchased Services and Other										2,380,000,000		2,311,000,000		2,189,000,000
Depreciation and Amortization										1,598,000,000		1,550,000,000		1,453,000,000
Equipment and Other Rents										335,000,000		334,000,000		372,000,000
Gains on Property Dispositions										(14,000,000)		(34,000,000)		(238,000,000)
Operating Income										5,346,000,000		5,467,000,000		5,902,000,000
Rail Operations | Operating Segments | Fuel - Locomotive
Segment Reporting, Asset Reconciling Item [Line Items]
Fuel										978,000,000		1,169,000,000		1,381,000,000
Rail Operations | Operating Segments | Fuel - Non- Locomotive
Segment Reporting, Asset Reconciling Item [Line Items]
Fuel										$ 102,000,000		$ 103,000,000		$ 105,000,000

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

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