Consolidated Statements of Income - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Income Statement [Abstract]
Revenues	$ 6,019	$ 5,968
Operating expenses:
Compensation and benefits	1,330	1,241
Fuel	964	861
Depreciation and amortization	647	627
Purchased services	625	668
Equipment rents	169	179
Materials and other	428	351
Total operating expenses	4,163	3,927
Operating income	1,856	2,041
Interest expense	257	255
Other (income) expense, net	(50)	(23)
Income before income taxes	1,649	1,809
Income Tax Expense (Benefit)	402	438
Net income	$ 1,247	$ 1,371