Consolidated Statements of Income (Unaudited) (USD $) In Millions, except Per Share data	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Consolidated Statements of Income [Abstract]
Railway operating revenues	$ 2,889	$ 2,456	$ 8,375	$ 7,124
Railway operating expenses:
Compensation and benefits	736	680	2,240	2,049
Purchased services and rents	403	377	1,191	1,086
Fuel	385	259	1,186	771
Depreciation	217	204	641	612
Materials and other	210	190	704	572
Total railway operating expenses	1,951	1,710	5,962	5,090
Income from railway operations	938	746	2,413	2,034
Other income, net	60	81	121	118
Interest expense on debt	114	113	339	347
Income before income taxes	884	714	2,195	1,805
Provision for income taxes	330	269	759	711
Net income	$ 554	$ 445	$ 1,436	$ 1,094
Per share amounts:
Basic	$ 1.61	$ 1.21	$ 4.09	$ 2.95
Diluted	$ 1.59	$ 1.19	$ 4.03	$ 2.91
Dividends	$ 0.43	$ 0.36	$ 1.23	$ 1.04