Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies - Additional Information (Detail)

v3.7.0.1
Summary of Significant Accounting Policies - Additional Information (Detail)
 12 Months Ended
Dec. 31, 2016
USD ($)
Segment
shares
Dec. 31, 2015
USD ($)
shares
Dec. 31, 2014
USD ($)
shares
Accounting Policies [Line Items]      
Restricted cash $ 251,000 $ 200,000  
Depreciation expense $ 997,000 817,000 $ 627,000
Number of operating segments | Segment 1    
Undelivered elements (training, installation, product and support services) $ 1,404,000 1,608,000  
Provision for sales returns 210,000 210,000  
Extended warranty contracts $ 1,500,000 1,400,000  
Revenue recognition, percentage of fair value of trade-in exchange 25.00%    
Advertising costs $ 351,000 929,000 543,000
Compensation cost related to stock options 3,065,000 3,350,000 $ 1,233,000
Total unrecognized compensation cost $ 4,000,000 $ 4,400,000  
Unrecognized share based compensation cost to be recognized over weighted-average period 2 years 6 months    
Outstanding stock options, restricted stock units and warrants excluded from diluted loss per share | shares 20,537,000 17,371,000 13,606,000
Executives      
Accounting Policies [Line Items]      
Fair value assumptions, forfeiture rate 4.87%    
Employees      
Accounting Policies [Line Items]      
Fair value assumptions, forfeiture rate 35.56%    
U S      
Accounting Policies [Line Items]      
Product warrant period 2 years 2 years 2 years
International      
Accounting Policies [Line Items]      
Product warrant period 28 months 28 months 16 months