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Long-Term Debt - Additional Information (Detail)
1 Months Ended
Aug. 31, 2015
USD ($)
Sep. 30, 2017
USD ($)
Sep. 30, 2017
EUR (€)
Debt Instrument [Line Items]      
Maximum borrowing capacity   $ 6,900,000 € 5,800,000
Amount outstanding under lines of credit   0  
Revolving Credit Facility [Member]      
Debt Instrument [Line Items]      
Debt instrument term (in years) 5 years    
Maximum borrowing capacity $ 125,000,000    
Amount outstanding under lines of credit   $ 0