Annual report pursuant to Section 13 and 15(d)

Stock-Based Compensation - Effects of Stock-Based Compensation Related to Stock Option and Restricted Stock Awards (Detail)

v3.8.0.1
Stock-Based Compensation - Effects of Stock-Based Compensation Related to Stock Option and Restricted Stock Awards (Detail) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]    
Stock-based compensation $ 1,895 $ 2,016
Cost of revenues    
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]    
Stock-based compensation 346 290
Research and development    
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]    
Stock-based compensation 133 172
General and administrative    
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]    
Stock-based compensation 1,299 1,446
Sales and marketing    
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]    
Stock-based compensation $ 117 $ 108