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Financial Instruments - Fair Value Hedges (Details) - USD ($) $ in Millions | Mar. 31, 2018 | Dec. 31, 2017
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Loans payable and current portion of long-term debt |  |
Derivative Instruments and Hedging Activities Disclosures [Line Items] |  |
Carrying Amount of Hedged Assets (Liabilities) | $ (998) | $ (983)
Cumulative Amount of Fair Value Hedging Adjustment Included in the Carrying Amount | 2 | 17
Long-Term Debt |  |
Derivative Instruments and Hedging Activities Disclosures [Line Items] |  |
Carrying Amount of Hedged Assets (Liabilities) | (5,083) | (5,146)
Cumulative Amount of Fair Value Hedging Adjustment Included in the Carrying Amount | 106 | 41
Long-Term Debt | Derivatives Not Designated as Hedging Instruments |  |
Derivative Instruments and Hedging Activities Disclosures [Line Items] |  |
Cumulative Amount of Fair Value Hedging Adjustment Included in the Carrying Amount | $ 9 | $ 11

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- Definition Hedged Liability, Fair Value Hedge + References No definition available. + Details
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- Definition Hedged Liability, Fair Value Hedge, Cumulative Increase (Decrease) + 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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- Details
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- Details
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- Details
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