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Long-Term Debt - Additional Information (Detail)
12 Months Ended
Aug. 31, 2015
USD ($)
Aug. 30, 2015
USD ($)
Dec. 31, 2017
USD ($)
Dec. 31, 2016
USD ($)
Dec. 31, 2015
USD ($)
Dec. 31, 2017
EUR (€)
Debt Instrument [Line Items]            
Maximum borrowing capacity     $ 7,000,000 $ 6,100,000   € 5,800,000
Debt issuance costs incurred     $ 445,000   $ 1,825,000  
2015 Credit Agreement [Member]            
Debt Instrument [Line Items]            
Credit agreement maturity date     Aug. 31, 2020      
Amount outstanding under lines of credit     $ 0      
2015 Credit Agreement [Member] | Revolving Credit Facility [Member]            
Debt Instrument [Line Items]            
Debt instrument term (in years)     5 years      
Maximum borrowing capacity $ 125,000,000          
Maximum borrowing capacity available for issuance of letters of credit 25,000,000          
Maximum additional borrowing capacity $ 50,000,000          
Line of credit, leverage ratio 3.0          
Line of credit, interest coverage ratio 300.00%          
Debt issuance costs incurred   $ 1,800,000        
Debt issuance costs, net of accumulated amortization     $ 1,000,000 1,300,000    
Debt issuance costs amortized or expensed     $ 1,000,000 $ 400,000 $ 600,000  
2015 Credit Agreement [Member] | Revolving Credit Facility [Member] | Maximum [Member]            
Debt Instrument [Line Items]            
Maximum borrowing capacity available for working capital and other general corporate purposes $ 50,000,000          
Line of credit facility, unused commitment fee percentage 0.40%          
2015 Credit Agreement [Member] | Revolving Credit Facility [Member] | Maximum [Member] | LIBOR [Member]            
Debt Instrument [Line Items]            
Margin on variable rate 2.50%          
2015 Credit Agreement [Member] | Revolving Credit Facility [Member] | Maximum [Member] | Base Rate [Member]            
Debt Instrument [Line Items]            
Margin on variable rate 1.50%          
2015 Credit Agreement [Member] | Revolving Credit Facility [Member] | Minimum [Member]            
Debt Instrument [Line Items]            
Line of credit facility, unused commitment fee percentage 0.25%          
2015 Credit Agreement [Member] | Revolving Credit Facility [Member] | Minimum [Member] | LIBOR [Member]            
Debt Instrument [Line Items]            
Margin on variable rate 1.75%          
2015 Credit Agreement [Member] | Revolving Credit Facility [Member] | Minimum [Member] | Base Rate [Member]            
Debt Instrument [Line Items]            
Margin on variable rate 0.75%