Operations And Segmentation (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2012		Jun. 30, 2011		Jun. 30, 2012		Jun. 30, 2011
Commodity Group Information [Line Items]
Freight revenues	$ 4,913		$ 4,595		$ 9,736		$ 8,843
Other revenues	308		263		597		505
Total operating revenues	5,221		4,858		10,333		9,348
Agriculture [Member]
Commodity Group Information [Line Items]
Freight revenues	854		849		1,712		1,656
Automotive [Member]
Commodity Group Information [Line Items]
Freight revenues	475		381		905		723
Chemicals [Member]
Commodity Group Information [Line Items]
Freight revenues	795		703		1,563		1,367
Coal [Member] [1]
Commodity Group Information [Line Items]
Freight revenues	869	[1]	950	[1]	1,864	[1]	1,902	[1]
Industrial Products [Member]
Commodity Group Information [Line Items]
Freight revenues	917		803		1,780		1,493
Intermodal [Member]
Commodity Group Information [Line Items]
Freight revenues	$ 1,003		$ 909		$ 1,912		$ 1,702

[1] Formerly titled Energy.