Annual report pursuant to Section 13 and 15(d)

Significant Accounting Policies - Additional Information (Detail)

v3.8.0.1
Significant Accounting Policies - Additional Information (Detail) - USD ($)
$ in Thousands
 3 Months Ended 12 Months Ended
Dec. 31, 2017
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Summary Of Significant Accounting Policies [Line Items]        
Maturity of temporary cash investments   3 months    
Goodwill impairment charges $ 10,700 $ 10,702    
Impairment of intangible assets   10,500    
Warranty and product liability $ 400 400 $ 400  
Revenue from sales taxes   4,100 5,200 $ 4,500
Advertisement Expenses   $ 300 200 300
Minimum        
Summary Of Significant Accounting Policies [Line Items]        
Product warranty period   1 year    
Maximum        
Summary Of Significant Accounting Policies [Line Items]        
Product warranty period   10 years    
Selling, General and Administrative Expenses        
Summary Of Significant Accounting Policies [Line Items]        
Warranty expense   $ 200 $ 200 $ 200