Consolidated Statements of Income (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Revenues	$ 5,651	$ 5,343	$ 16,257	$ 15,407
Operating expenses:
Compensation and benefits	1,197	1,149	3,464	3,344
Fuel	1,145	1,089	3,343	3,286
Purchased services	618	601	1,852	1,784
Depreciation and amortization	493	475	1,465	1,408
Equipment rents	205	204	608	605
Materials and other	253	156	740	608
Total operating expenses	3,911	3,674	11,472	11,035
Operating income	1,740	1,669	4,785	4,372
Interest expense	181	157	536	460
Other expense, net	3	4	7	9
Income before income taxes	1,556	1,508	4,242	3,903
Income tax expense	567	571	1,571	1,463
Net income	$ 989	$ 937	$ 2,671	$ 2,440