Consolidated Statements of Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Statement [Abstract]
Revenues	$ 25,888	$ 23,282	$ 20,869
Operating expenses:
Compensation and benefits	5,321	4,767	4,609
Fuel	4,581	2,766	1,789
Purchased services	2,697	2,715	2,554
Depreciation and amortization	2,528	2,456	2,476
Equipment rents	720	677	664
Materials and other	1,441	1,103	1,037
Total operating expenses	17,288	14,484	13,129
Operating income	8,600	8,798	7,740
Interest expense	1,025	1,032	1,037
Other (income) expense, net	(133)	(95)	(89)
Income before income taxes	7,708	7,861	6,792
Income tax expense	1,762	1,871	1,631
Net income	$ 5,946	$ 5,990	$ 5,161