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Derivatives - Summary of Gains and Losses on Derivative Contracts (Detail) - USD ($) $ in Thousands | 3 Months Ended
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Mar. 31, 2019 | Mar. 31, 2018
Derivative Instruments and Hedging Activities Disclosures [Line Items] |  |
Gain (loss) on derivative contract | $ 4,792 | $ 11,274
Forwards [Member] |  |
Derivative Instruments and Hedging Activities Disclosures [Line Items] |  |
Gain (loss) on derivative contract | (113) | 292
Futures [Member] |  |
Derivative Instruments and Hedging Activities Disclosures [Line Items] |  |
Gain (loss) on derivative contract | 4,248 | 5,908
Foreign Exchange/Commodities Options [Member] |  |
Derivative Instruments and Hedging Activities Disclosures [Line Items] |  |
Gain (loss) on derivative contract | 63 | 4,599
Foreign Exchange Swaps [Member] |  |
Derivative Instruments and Hedging Activities Disclosures [Line Items] |  |
Gain (loss) on derivative contract | $ 594 | 378
Equity Options [Member] |  |
Derivative Instruments and Hedging Activities Disclosures [Line Items] |  |
Gain (loss) on derivative contract |  | 102
Interest Rate Swaps [Member] |  |
Derivative Instruments and Hedging Activities Disclosures [Line Items] |  |
Gain (loss) on derivative contract |  | $ (5)

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- Definition Amount of increase (decrease) in the fair value of derivatives recognized in the income statement. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4A -Subparagraph (b)(1) -URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5618551-113959 + Details
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