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Recently Adopted and Recently Issued Accounting Guidance (Details) - USD ($) $ in Millions |  | 3 Months Ended | 9 Months Ended |
--- | --- | --- | --- | ---
Mar. 30, 2012 | Sep. 30, 2018 | Sep. 30, 2017 | Sep. 30, 2018 | Sep. 30, 2017 | Dec. 31, 2017
Accounting Policies [Abstract] |  |  |  |  |  |
Restricted cash |  | $ 7 | $ 5 | $ 7 | $ 5 | $ 4
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |
Reclassification of cash received related to beneficial interest in previously transferred trade accounts receivables | $ 50 |  |  | 693 | 514 |
Reclassification of cash paid for debt prepayments including extinguishment costs from operating to financing activities |  |  |  | 17 | 52 |
Adjustment to operating income based on adoption of new accounting guidance |  | $ 345 | 310 | $ 1,002 | 913 |
ASU 2016-15 |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |
Reclassification of cash paid for debt prepayments including extinguishment costs from operating to financing activities |  |  |  |  | (52) |
Adjustments for New Accounting Pronouncement |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |
Adjustment to operating income based on adoption of new accounting guidance |  |  | $ 39 |  | $ 116 |

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- Definition Amount of cash outflow for cost from early extinguishment and prepayment of debt. Includes, but is not limited to, third-party cost, premium paid, and other fee paid to lender directly for debt extinguishment or debt prepayment. Excludes accrued interest. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 15 -Subparagraph (g) -URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3291-108585 + Details
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