v2.4.0.8
Properties (Details) (USD $)
In Millions, unless otherwise specified
 6 Months Ended 12 Months Ended
Jun. 30, 2014
Dec. 31, 2013
Property, Plant and Equipment [Line Items]    
Cost $ 61,442 $ 59,812
Accumulated depreciation 16,541 16,063
Net book value 44,901 43,749
Land [Member]
    
Property, Plant and Equipment [Line Items]    
Cost 5,134 5,120
Net book value 5,134 5,120
Road: Rail and Other Track Material [Member]
    
Property, Plant and Equipment [Line Items]    
Cost 14,219 13,861
Accumulated depreciation 5,105 4,970
Net book value 9,114 8,891
Estimated useful life 33 years 35 years
Road: Ties [Member]
    
Property, Plant and Equipment [Line Items]    
Cost 8,968 8,785
Accumulated depreciation 2,396 2,310
Net book value 6,572 6,475
Estimated useful life 33 years 33 years
Road: Ballast [Member]
    
Property, Plant and Equipment [Line Items]    
Cost 4,720 4,621
Accumulated depreciation 1,220 1,171
Net book value 3,500 3,450
Estimated useful life 34 years 34 years
Road: Other Roadway [Member]
    
Property, Plant and Equipment [Line Items]    
Cost 15,996 [1] 15,596 [1]
Accumulated depreciation 2,796 [1] 2,726 [1]
Net book value 13,200 [1] 12,870 [1]
Estimated useful life 47 years [1] 48 years [1]
Total Road [Member]
    
Property, Plant and Equipment [Line Items]    
Cost 43,903 42,863
Accumulated depreciation 11,517 11,177
Net book value 32,386 31,686
Equipment: Locomotives [Member]
    
Property, Plant and Equipment [Line Items]    
Cost 7,882 7,518
Accumulated depreciation 3,625 3,481
Net book value 4,257 4,037
Estimated useful life 20 years 20 years
Equipment: Freight Cars [Member]
    
Property, Plant and Equipment [Line Items]    
Cost 2,073 2,085
Accumulated depreciation 969 1,000
Net book value 1,104 1,085
Estimated useful life 25 years 25 years
Equipment: Work Equipment And Other [Member]
    
Property, Plant and Equipment [Line Items]    
Cost 571 561
Accumulated depreciation 135 119
Net book value 436 442
Estimated useful life 18 years 18 years
Total Equipment [Member]
    
Property, Plant and Equipment [Line Items]    
Cost 10,526 10,164
Accumulated depreciation 4,729 4,600
Net book value 5,797 5,564
Technology and Other [Member]
    
Property, Plant and Equipment [Line Items]    
Cost 803 711
Accumulated depreciation 295 286
Net book value 508 425
Estimated useful life 11 years 10 years
Construction in Progress [Member]
    
Property, Plant and Equipment [Line Items]    
Cost 1,076 954
Accumulated depreciation 0 0
Net book value $ 1,076 $ 954
[1] Other roadway includes grading, bridges and tunnels, signals, buildings, and other road assets.