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Fair Value Measurements - Losses Included in Earnings Relating to Assets Still Held at End of Period (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Millions | 3 Months Ended
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Mar. 31, 2018 | Mar. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
The amount of total losses for the period included in earnings attributable to the change in unrealized losses relating to assets still held at the end of period: | $ (3) | $ (12)
Derivative |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
The amount of total losses for the period included in earnings attributable to the change in unrealized losses relating to assets still held at the end of period: | (3) | (13)
Contingent Consideration |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
The amount of total losses for the period included in earnings attributable to the change in unrealized losses relating to assets still held at the end of period: | $ 0 | $ 1

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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 unrealized (holding) gain (loss) which is included in the statement of income (or changes in net assets) related to those liabilities still held at the reporting date for which fair value is measured on a recurring basis using significant unobservable inputs (Level 3). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
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