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Schedule Of Valuation And Qualifying Accounts (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Presented in Consolidated Statements of Financial Position [Abstract] |  |  |
Allowance for doubtful accounts - current | $ 17 | $ 4 |
Allowance for doubtful accounts - long-term | 51 | 35 |
Accrued casualty costs, current | 177 | 190 |
Accrued Casualty Costs [Member] |  |  |
Schedule Of Valuation And Qualifying Accounts [Line Items] |  |  |
Balance, beginning of period | 657 | 709 | $ 684
Charges/(reduction) to expense | 231 | 215 | 202
Net recoveries/(write-offs), cash payments and other reductions | (244) | (267) | (177)
Balance, end of period | 644 | 657 | 709
Presented in Consolidated Statements of Financial Position [Abstract] |  |  |
Accrued casualty costs, current | 177 | 190 | 211
Accrued casualty costs, long-term | 467 | 467 | 498
Balance, end of period | $ 644 | $ 657 | $ 709

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