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Derivatives - Summary of Primary Net Hedging Positions and Corresponding Fair Values (Detail) - USD ($) $ in Thousands | Jun. 30, 2018 | Dec. 31, 2017
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Derivative [Line Items] |  |
Currency Hedged (Buy/Sell), Gross Notional Value, Net | $ 178,327 | $ 208,922
Currency Hedged (Buy/Sell), Fair Value, (Liability)/Asset, Net | 2,844 | (6,030)
Forward Exchange Contracts [Member] | U.S. Dollar/Japanese Yen [Member] |  |
Derivative [Line Items] |  |
Currency Hedged (Buy/Sell), Gross Notional Value, Net | 47,023 | 70,175
Currency Hedged (Buy/Sell), Fair Value, (Liability)/Asset, Net | 416 | (233)
Forward Exchange Contracts [Member] | U.S. Dollar/South Korean Won [Member] |  |
Derivative [Line Items] |  |
Currency Hedged (Buy/Sell), Gross Notional Value, Net | 73,485 | 79,672
Currency Hedged (Buy/Sell), Fair Value, (Liability)/Asset, Net | 1,226 | (3,799)
Forward Exchange Contracts [Member] | U.S. Dollar/Euro [Member] |  |
Derivative [Line Items] |  |
Currency Hedged (Buy/Sell), Gross Notional Value, Net | 26,059 | 26,140
Currency Hedged (Buy/Sell), Fair Value, (Liability)/Asset, Net | 435 | (1,047)
Forward Exchange Contracts [Member] | U.S. Dollar/U.K. Pound Sterling [Member] |  |
Derivative [Line Items] |  |
Currency Hedged (Buy/Sell), Gross Notional Value, Net | 12,763 | 12,104
Currency Hedged (Buy/Sell), Fair Value, (Liability)/Asset, Net | 250 | (337)
Forward Exchange Contracts [Member] | U.S. Dollar/Taiwan Dollar [Member] |  |
Derivative [Line Items] |  |
Currency Hedged (Buy/Sell), Gross Notional Value, Net | 18,997 | 20,831
Currency Hedged (Buy/Sell), Fair Value, (Liability)/Asset, Net | $ 517 | $ (614)

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