Consolidated Statements of Income - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Income Statement [Abstract]
Revenues	$ 5,739	$ 5,828	$ 11,399	$ 11,847
Operating expenses:
Compensation and benefits	1,321	1,393	2,733	2,723
Fuel	822	833	1,676	1,797
Depreciation and amortization	666	653	1,327	1,300
Purchased services	508	596	1,011	1,221
Equipment rents	173	171	347	340
Materials and other	426	372	762	800
Total operating expenses	3,916	4,018	7,856	8,181
Operating income	1,823	1,810	3,543	3,666
Interest expense	267	256	532	513
Other (income) expense, net	(66)	(61)	(130)	(111)
Income before income taxes	1,622	1,615	3,141	3,264
Income Tax Expense (Benefit)	395	351	771	753
Net income	$ 1,227	$ 1,264	$ 2,370	$ 2,511