Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 13
-Sentence Column B

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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.

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- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4D
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- Definition

Amount of realized and unrealized gain (loss) of derivative instruments not designated or qualifying as hedging instruments.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4CC
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- Definition

Period the derivative contract is outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

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Derivative Instruments - Additional Information (Detail) - USD ($) $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Not Designated As Hedging Instrument
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Net (loss) gain recognized in the consolidated statements of operations for derivatives not designated as hedging instruments	$ (23,400)	$ 70,700	$ (23,353)	$ 70,711	$ (9,425)
Foreign currency forward exchange contracts
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional amount of foreign currency forward exchange contracts			962,100	987,700
Foreign currency forward exchange contracts \| Not Designated As Hedging Instrument \| Cost of sales
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Net (loss) gain recognized in the consolidated statements of operations for derivatives not designated as hedging instruments			$ (244)	511	1,631
Maximum
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Maximum term for foreign currency forward exchange contracts			18 months
Reclassification out of Accumulated Other Comprehensive Income \| Derivative Instruments \| Foreign currency forward exchange contracts \| Designated As Hedging Instrument \| Cost of sales
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net			$ (8,427)	$ (16,810)	$ 16,627