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Loss on Asset Disposal (Details)
$ in Millions
3 Months Ended 12 Months Ended
Mar. 31, 2021
USD ($)
Mar. 31, 2020
USD ($)
Dec. 31, 2020
USD ($)
locomotive
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]      
Loss on locomotives $ (8) $ (8)  
Railroad Transportation Equipment      
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]      
Number of locomotives classified as Held-for-Sale | locomotive     703
Loss on locomotives     $ 385
Tax benefit on loss from sale of locomotives     $ 97