The effective portion of net gain (loss) reclassified from accumulated other comprehensive income into income on derivative instruments designated and qualifying as hedging instruments.

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The portion of gains and losses (net) on derivative instruments designated and qualifying as hedging instruments representing (a) the amount of the hedge ineffectiveness and (b) the amount, if any, excluded from the assessment of hedge effectiveness.

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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.

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No definition available.

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Amount before tax of increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss).

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Derivative Financial Instruments - Impact of Derivative Instruments on Consolidated Statement of Operations (Detail) - Cash Flow Hedging [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Derivative [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion)	$ (1,870)	$ (1,594)
Other Income (Expenses) - Others [Member]
Derivative [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion)			$ (1,937)	$ 909
Amount of Gain (Loss) Recognized in Statement of Operations on Derivatives (Ineffective Portion)	(1,632)	(467)	(1,708)	170
Net Sales [Member]
Derivative [Line Items]
Amount of Gain Reclassified from AOCI into Statement of Operations (Effective Portion)	2,035	808	4,641	1,305
Zero Cost Collars [Member]
Derivative [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion)	(1,009)	(1,620)
Zero Cost Collars [Member] \| Other Income (Expenses) - Others [Member]
Derivative [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion)			(1,142)	883
Amount of Gain (Loss) Recognized in Statement of Operations on Derivatives (Ineffective Portion)	(247)	(368)	(318)	269
Zero Cost Collars [Member] \| Net Sales [Member]
Derivative [Line Items]
Amount of Gain Reclassified from AOCI into Statement of Operations (Effective Portion)	865	808	2,191	1,305
Forward [Member]
Derivative [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion)	(861)	26
Forward [Member] \| Other Income (Expenses) - Others [Member]
Derivative [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion)			(795)	26
Amount of Gain (Loss) Recognized in Statement of Operations on Derivatives (Ineffective Portion)	(1,385)	$ (99)	(1,390)	$ (99)
Forward [Member] \| Net Sales [Member]
Derivative [Line Items]
Amount of Gain Reclassified from AOCI into Statement of Operations (Effective Portion)	$ 1,170		$ 2,450