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Financial Instruments - Fair Value of Hedges (Details) - USD ($) $ in Millions | Dec. 31, 2018 | Dec. 31, 2017
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Derivative [Line Items] |  |
Hedging adjustment gains related to discontinued hedging relationships |  | $ 11
Loans payable and current portion of long-term debt |  |
Derivative [Line Items] |  |
Carrying Amount of Hedged Liabilities | $ 0 | 983
Cumulative Amount of Fair Value Hedging Adjustment Increase (Decrease) Included in the Carrying Amount | 0 | (17)
Long-Term Debt |  |
Derivative [Line Items] |  |
Carrying Amount of Hedged Liabilities | 4,560 | 5,146
Cumulative Amount of Fair Value Hedging Adjustment Increase (Decrease) Included in the Carrying Amount | $ (82) | $ (41)

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- Definition Amount as of the balance sheet date of the unamortized adjustment to the carrying value of an interest-bearing hedged item made under an effective fair value hedge that is amortized upon discontinuation of the fair value hedge. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 25 -Section 35 -Paragraph 9 -URI http://asc.fasb.org/extlink&oid=109978511&loc=d3e75592-113984 + 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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