Consolidated Statements of Income (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Revenues	$ 5,002	$ 4,533
Operating expenses:
Compensation and benefits	1,117	1,075
Fuel	1,095	939
Purchased services	569	547
Depreciation and amortization	463	446
Equipment rents	202	192
Materials and other	291	230
Total operating expenses	3,737	3,429
Operating income	1,265	1,104
Interest expense	148	136
Other expense, net	2	3
Income before income taxes	1,115	965
Income tax expense	414	358
Net income	$ 701	$ 607