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Derivative Instruments and Risk Management - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Derivative [Line Items]
Interest rate swaps notional value	$ 149,000,000
Foreign currency forward exchange contracts notional value	$ 79,200,000
Maximum [Member]
Derivative [Line Items]
Maturity period of foreign currency forward exchange contracts	1 year
Interest Rate Swaps [Member] | Maximum [Member]
Derivative [Line Items]
Derivative fixed interest rate	1.67%
Interest Rate Swaps [Member] | Minimum [Member]
Derivative [Line Items]
Derivative fixed interest rate	1.42%
Not Designated as Hedging Instrument [Member] | Foreign Currency Forward Exchange Contracts [Member] | Other net income/(expense) [Member]
Derivative [Line Items]
Amount of gain/(loss) recognized in income	$ (900,000)	$ 4,400,000
Designated as Hedging Instrument [Member] | Interest Rate Swaps [Member] | Accumulated Other Comprehensive Loss [Member]
Derivative [Line Items]
Amount of gain/(loss) recognized in income	$ 1,100,000	$ 400,000

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- Definition

Notional Value Of Foreign Currency Forward Exchange Contracts.

+ References

No definition available.

+ Details

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- Definition

Notional value of interest rate swap agreement.

+ References

No definition available.

+ Details

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- Definition

Fixed interest rate related to the interest rate derivative.

+ References

No definition available.

+ Details

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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

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

+ References

No definition available.

+ Details

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- Definition

Aggregate net gain (loss) on all derivative instruments recognized in earnings during the period, before tax effects.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5618551-113959

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