Fair Value Measurements - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Fair Values Of Financial Assets And Liabilities Including Derivative Financial Instruments [Line Items]
Effective portion of change in fair value of foreign currency forward contracts	$ (2,640,000)	$ 1,029,000
Long-term debt	295,987,000	297,094,000
Quoted Prices in Active Markets for Identical Assets Level (1)
Fair Values Of Financial Assets And Liabilities Including Derivative Financial Instruments [Line Items]
Fair value of long term debt	329,329,000	331,941,000
Foreign Exchange Contracts
Fair Values Of Financial Assets And Liabilities Including Derivative Financial Instruments [Line Items]
Notional amount of the foreign currency derivative instruments	$ 134,530,000	$ 89,414,000
Foreign Exchange Contracts | Maximum
Fair Values Of Financial Assets And Liabilities Including Derivative Financial Instruments [Line Items]
Maturity period of hedges	12 months
Interest Rate Swap | Maximum
Fair Values Of Financial Assets And Liabilities Including Derivative Financial Instruments [Line Items]
Maturity period of hedges	4 years