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Basis of Presentation and Summary Accounting Policies - Additional Information (Detail) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended 12 Months Ended
Jun. 30, 2018
Jun. 30, 2017
Jun. 30, 2018
Jun. 30, 2017
Dec. 31, 2017
Dec. 31, 2016
Schedule Of Significant Accounting Policies [Line Items]            
Percentage of total annual net sales in the third and fourth quarters         60.00% 61.00%
Restructuring charges $ 395 $ 254 $ 801 $ 254    
Employee Severance            
Schedule Of Significant Accounting Policies [Line Items]            
Restructuring charges 400   800      
Accrued restructuring change 400   400      
Receivables Purchase Agreement            
Schedule Of Significant Accounting Policies [Line Items]            
Sale of receivable 19,100 17,600 38,700 39,200    
Receivables Purchase Agreement | Selling, General and Administrative Expenses            
Schedule Of Significant Accounting Policies [Line Items]            
Charge related to sale of receivables $ 99 $ 63 $ 189 $ 130