Consolidated Statements of Income - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Income Statement [Abstract]
Revenues	$ 5,660	$ 6,019
Operating expenses:
Compensation and benefits	1,412	1,330
Fuel	854	964
Depreciation and amortization	661	647
Purchased services	503	625
Equipment rents	174	169
Materials and other	336	428
Total operating expenses	3,940	4,163
Operating income	1,720	1,856
Interest expense	265	257
Other (income) expense, net	(64)	(50)
Income before income taxes	1,519	1,649
Income Tax Expense (Benefit)	376	402
Net income	$ 1,143	$ 1,247