Consolidated Statements of Income (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Revenues	$ 5,322	$ 5,062	$ 10,606	$ 10,064
Operating expenses:
Compensation and benefits	1,128	1,078	2,267	2,195
Fuel	1,076	1,102	2,198	2,197
Purchased services	617	614	1,234	1,183
Depreciation and amortization	489	470	972	933
Equipment rents	205	199	403	401
Materials and other	230	161	487	452
Total operating expenses	3,745	3,624	7,561	7,361
Operating income	1,577	1,438	3,045	2,703
Interest expense	177	155	355	303
Other expense, net	3	3	4	5
Income before income taxes	1,397	1,280	2,686	2,395
Income tax expense	513	478	1,004	892
Net income	$ 884	$ 802	$ 1,682	$ 1,503