Consolidated Statements of Income (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Operating revenues [Abstract]
Freight revenues	$ 20,684	$ 19,686	$ 18,508
Other revenues	1,279	1,240	1,049
Total operating revenues	21,963	20,926	19,557
Operating expenses [Abstract]
Compensation and benefits	4,807	4,685	4,681
Fuel	3,534	3,608	3,581
Purchased services and materials	2,315	2,143	2,005
Depreciation	1,777	1,760	1,617
Equipment and other rents	1,235	1,197	1,167
Other	849	788	782
Total operating expenses	14,517	14,181	13,833
Operating income	7,446	6,745	5,724
Other income (Note 6)	128	108	112
Interest expense	(526)	(535)	(572)
Income before income taxes	7,048	6,318	5,264
Income taxes (Note 7)	(2,660)	(2,375)	(1,972)
Net income	$ 4,388	$ 3,943	$ 3,292
Share and Per Share (Note 8) [Abstract]
Earnings per share - basic	$ 9.47	$ 8.33	$ 6.78
Earnings per share - diluted	$ 9.42	$ 8.27	$ 6.72
Weighted average number of shares - basic	463.3	473.1	485.7
Weighted average number of shares - diluted	465.8	476.5	489.8
Dividends declared per share	$ 2.96	$ 2.49	$ 1.93