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v3.20.4

Properties (Details) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2020 USD ($) item | Dec. 31, 2019 USD ($) | Dec. 31, 2018 USD ($)
Property, Plant and Equipment [Line Items] |  |  |  |
Cost |  | $ 75,420 | $ 74,246 |
Accumulated depreciation |  | 21,259 | 20,330 |
Net book value |  | $ 54,161 | 53,916 |
Depreciable asset classes description |  | We currently have more than 60 depreciable asset classes, and we may increase or decrease the number of asset classes due to changes in technology, asset strategies, or other factors. |  |
Total repairs and maintenance expense |  | $ 2,000 | 2,300 | $ 2,500
Non-cash impairment charge |  | 278 |  |
Land [Member] |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |
Cost |  | 5,246 | 5,276 |
Accumulated depreciation |  |  |  |
Net book value |  | 5,246 | 5,276 |
Road: Rail and Other Track Material [Member] |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |
Cost |  | 17,620 | 17,178 |
Accumulated depreciation |  | 6,631 | 6,381 |
Net book value |  | $ 10,989 | $ 10,797 |
Estimated useful life |  | 42 years | 42 years |
Road: Ties [Member] |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |
Cost |  | $ 11,051 | $ 10,693 |
Accumulated depreciation |  | 3,331 | 3,186 |
Net book value |  | $ 7,720 | $ 7,507 |
Estimated useful life |  | 34 years | 34 years |
Road: Ballast [Member] |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |
Cost |  | $ 5,926 | $ 5,752 |
Accumulated depreciation |  | 1,753 | 1,669 |
Net book value |  | $ 4,173 | $ 4,083 |
Estimated useful life |  | 34 years | 34 years |
Road: Other Roadway [Member] |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |
Cost | [1] | $ 21,030 | $ 20,331 |
Accumulated depreciation | [1] | 4,329 | 4,056 |
Net book value | [1] | $ 16,701 | $ 16,275 |
Estimated useful life | [1] | 48 years | 48 years |
Total Road [Member] |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |
Cost |  | $ 55,627 | $ 53,954 |
Accumulated depreciation |  | 16,044 | 15,292 |
Net book value |  | $ 39,583 | 38,662 |
Term of Depreciation Studies |  | 6 years |  |
Equipment: Locomotives [Member] |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |
Cost |  | $ 9,375 | 9,467 |
Accumulated depreciation |  | 3,555 | 3,434 |
Net book value |  | $ 5,820 | $ 6,033 |
Estimated useful life |  | 17 years | 18 years |
Equipment: Freight Cars [Member] |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |
Cost |  | $ 2,118 | $ 2,083 |
Accumulated depreciation |  | 789 | 779 |
Net book value |  | $ 1,329 | $ 1,304 |
Estimated useful life |  | 25 years | 25 years |
Equipment: Work Equipment and Other [Member] |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |
Cost |  | $ 1,107 | $ 1,081 |
Accumulated depreciation |  | 351 | 322 |
Net book value |  | $ 756 | $ 759 |
Estimated useful life |  | 18 years | 18 years |
Total Equipment [Member] |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |
Cost |  | $ 12,600 | $ 12,631 |
Accumulated depreciation |  | 4,695 | 4,535 |
Net book value |  | $ 7,905 | 8,096 |
Term of Depreciation Studies |  | 3 years |  |
Technology and Other [Member] |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |
Cost |  | $ 1,199 | 1,136 |
Accumulated depreciation |  | 520 | 503 |
Net book value |  | $ 679 | $ 633 |
Estimated useful life |  | 13 years | 12 years |
Construction in Progress [Member] |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |
Cost |  | $ 748 | $ 1,249 |
Accumulated depreciation |  |  |  |
Net book value |  | $ 748 | $ 1,249 |
Minimum [Member] |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |
Number of depreciable asset classes | item |  | 60 |  |
[1] | Other roadway includes grading, bridges and tunnels, signals, buildings, and other road assets.

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