Consolidated Statements of Income - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Income Statement [Abstract]
Revenues	$ 5,828	$ 6,640	$ 11,847	$ 12,608
Operating expenses:
Compensation and benefits	1,393	1,231	2,723	2,472
Fuel	833	1,276	1,797	2,137
Depreciation and amortization	653	620	1,300	1,247
Purchased services	596	670	1,221	1,338
Equipment rents	171	185	340	364
Materials and other	372	279	800	630
Total operating expenses	4,018	4,261	8,181	8,188
Operating income	1,810	2,379	3,666	4,420
Interest expense	256	254	513	509
Other (income) expense, net	(61)	(26)	(111)	(49)
Income before income taxes	1,615	2,151	3,264	3,960
Income Tax Expense (Benefit)	351	487	753	925
Net income	$ 1,264	$ 1,664	$ 2,511	$ 3,035