Consolidated Statements of Income - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Income Statement [Abstract]
Revenues	$ 5,417	$ 5,762
Operating expenses:
Compensation and benefits	1,244	1,400
Purchased services	666	713
Depreciation and amortization	615	591
Fuel	614	711
Equipment rents	165	191
Materials and other	290	377
Total operating expenses	3,594	3,983
Operating income	1,823	1,779
Interest expense	262	268
Other (income) expense, net	(23)	(154)
Income before income taxes	1,584	1,665
Income tax expense	394	412
Net income	$ 1,190	$ 1,253