Consolidated Statements of Income (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenues	$ 23,239	$ 22,014	$ 20,835
Operating expenses:
Compensation and benefits	5,023	4,651	4,505
Fuel	4,478	4,503	4,459
Purchased services	2,592	2,418	2,374
Depreciation and amortization	2,123	1,973	1,889
Equipment rents	867	822	810
Materials and other	1,143	980	786
Total operating expenses	16,226	15,347	14,823
Operating income	7,013	6,667	6,012
Interest expense	833	729	623
Other expense, net	11	10	12
Income before income taxes	6,169	5,928	5,377
Income tax expense	2,300	2,135	2,005
Net income	$ 3,869	$ 3,793	$ 3,372