Consolidated Statements of Income - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenues	$ 5,878	$ 5,250	$ 11,502	$ 10,435
Operating expenses:
Compensation and benefits	1,328	1,255	2,643	2,552
Purchased services	714	609	1,406	1,235
Fuel	830	577	1,597	1,182
Depreciation and amortization	575	592	1,146	1,165
Equipment rents	167	196	359	392
Materials and other	381	247	721	555
Total operating expenses	3,995	3,476	7,872	7,081
Operating income	1,883	1,774	3,630	3,354
Interest expense	256	256	512	508
Other (income) expense, net	(28)	(19)	(50)	(36)
Income before income taxes	1,655	1,537	3,168	2,882
Income tax expense	346	579	714	1,086
Net income	$ 1,309	$ 958	$ 2,454	$ 1,796