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Financial Instruments - Effect of Net Investment Hedges (Details) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended |
--- | --- | --- | ---
Jun. 30, 2018 | Jun. 30, 2017 | Jun. 30, 2018 | Jun. 30, 2017 | Dec. 31, 2017
Loans payable and current portion of long-term debt |  |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |  |
Carrying Amount of Hedged Liabilities | $ 554 |  | $ 554 |  | $ 983
Cumulative Amount of Fair Value Hedging Adjustment Increase (Decrease) Included in the Carrying Amount | 5 |  | 5 |  | (17)
Long-Term Debt |  |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |  |
Carrying Amount of Hedged Liabilities | 4,511 |  | 4,511 |  | 5,146
Cumulative Amount of Fair Value Hedging Adjustment Increase (Decrease) Included in the Carrying Amount | (129) |  | (129) |  | $ (41)
Foreign exchange contracts |  |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |  |
Amount of Pretax (Gain) Loss Recognized in Other Comprehensive Income (1) | (12) | $ 0 | (14) | $ 0 |
Foreign exchange contracts | Other (income) expense, net |  |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |  |
Amount of Pretax (Gain) Loss Recognized in Other (income) expense, net for Amounts Excluded from Effectiveness Testing | (3) | 0 | (3) | 0 |
Euro-denominated notes |  |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |  |
Amount of Pretax (Gain) Loss Recognized in Other Comprehensive Income (1) | (271) | 204 | (92) | 339 |
Euro-denominated notes | Other (income) expense, net |  |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |  |
Amount of Pretax (Gain) Loss Recognized in Other (income) expense, net for Amounts Excluded from Effectiveness Testing | $ 0 | $ 0 | $ 0 | $ 0 |

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- Definition Other Comprehensive Income (Loss), Net Investment Hedge, Gain (Loss), Before Reclassification, Pretax + References No definition available. + Details
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- Definition Other Comprehensive Income (Loss), Net Investment Hedge, Gain (Loss), Reclassification, Pretax + References No definition available. + Details
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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- Definition Amount of liability hedged in fair value hedging relationship. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4EE -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=109980867&loc=SL109999712-113959 + Details
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- Definition Amount of cumulative increase (decrease) in fair value of hedged liability in fair value hedge, attributable to hedged risk. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4EE -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109980867&loc=SL109999712-113959 + Details
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