Consolidated Statements of Income - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Income Statement [Abstract]
Revenues	$ 6,640	$ 5,809	$ 12,608	$ 11,210
Operating expenses:
Compensation and benefits	1,231	1,163	2,472	2,346
Fuel	1,276	693	2,137	1,243
Purchased services	670	686	1,338	1,351
Depreciation and amortization	620	612	1,247	1,231
Equipment rents	185	166	364	337
Materials and other	279	271	630	595
Total operating expenses	4,261	3,591	8,188	7,103
Operating income	2,379	2,218	4,420	4,107
Interest expense	254	261	509	519
Other (income) expense, net	(26)	(22)	(49)	(50)
Income before income taxes	2,151	1,979	3,960	3,638
Income Tax Expense (Benefit)	487	463	925	871
Net income	$ 1,664	$ 1,516	$ 3,035	$ 2,767