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Commitments And Contingencies (Commitments And Contingencies Activity) (Details) - USD ($) $ in Millions | 9 Months Ended
--- | ---
Sep. 30, 2021 | Sep. 30, 2020
Liability Activity [Abstract] |  |
Current portion, ending balance at September 30 | $ 182 |
Environmental [Abstract] |  |
Beginning balance. | 233 | $ 227
Accruals | 56 | 55
Payments | (41) | (47)
Ending balance at September 30. | 248 | 235
Current portion, ending balance at September 30. | 60 | 65
Personal Injury [Member] |  |
Liability Activity [Abstract] |  |
Beginning balance | 270 | 265
Current year accruals | 69 | 52
Changes in estimates for prior years | 19 | (4)
Payments | (55) | (47)
Ending balance at September 30 | 303 | 266
Current portion, ending balance at September 30 | $ 62 | $ 62

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- Definition Total costs accrued as of the balance sheet date for environmental loss contingencies. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=121557415&loc=d3e14326-108349 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 25 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6395460&loc=d3e13647-108346 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 30 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=6393242&loc=d3e13207-110859 + Details
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