Nature Of Operations (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Segment Reporting, Disclosure of Entity's Reportable Segments [Abstract]
Network route miles	31,838								31,838
Route miles owned	26,009								26,009
Commodity Group Information [Line Items]
Freight revenues									$ 20,684	$ 19,686	$ 18,508
Other revenues									1,279	1,240	1,049
Total operating revenues	5,630	5,573	5,470	5,290	5,250	5,343	5,221	5,112	21,963	20,926	19,557
Freight revenues - Mexico									2,100	1,900	1,800
Agriculture [Member]
Commodity Group Information [Line Items]
Freight revenues									3,276	3,280	3,324
Automotive [Member]
Commodity Group Information [Line Items]
Freight revenues									2,077	1,807	1,510
Chemicals [Member]
Commodity Group Information [Line Items]
Freight revenues									3,501	3,238	2,815
Coal [Member]
Commodity Group Information [Line Items]
Freight revenues									3,978	3,912	4,084
Industrial Products [Member]
Commodity Group Information [Line Items]
Freight revenues									3,822	3,494	3,166
Intermodal [Member]
Commodity Group Information [Line Items]
Freight revenues									$ 4,030	$ 3,955	$ 3,609