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Financial Instruments - Fair Value Hedges (Details) - USD ($) $ in Millions | Sep. 30, 2018 | Dec. 31, 2017
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Derivative Instruments and Hedging Activities Disclosures [Line Items] |  |
Cumulative Amount of Fair Value Hedging Adjustment Increase (Decrease) Included in the Carrying Amount | $ 6 | $ 11
Loans payable and current portion of long-term debt |  |
Derivative Instruments and Hedging Activities Disclosures [Line Items] |  |
Carrying Amount of Hedged Liabilities | 553 | 983
Hedged Liability, Fair Value Hedge, Cumulative Increase (Decrease) | 3 | (17)
Long-Term Debt |  |
Derivative Instruments and Hedging Activities Disclosures [Line Items] |  |
Carrying Amount of Hedged Liabilities | 4,503 | 5,146
Hedged Liability, Fair Value Hedge, Cumulative Increase (Decrease) | $ (138) | $ (41)

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- Definition Amount of cumulative increase (decrease) in fair value of hedged liability in fair value hedge, attributable to hedged risk, remaining after discontinued hedge. + 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 (d) -URI http://asc.fasb.org/extlink&oid=109980867&loc=SL109999712-113959 + 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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