Description of Business and Summary of Significant Accounting Policies (Tables)
 12 Months Ended
Dec. 31, 2013
Description of Business and Summary of Significant Accounting Policies  
Schedule of revenue from U.S., Canadian and all other international dealers and distributors combined

The following table sets forth revenue from the U.S., Canadian and all other international dealers and distributors combined (in thousands):

 
   Years Ended December 31,  
 
   2011   2012   2013  

Revenue-United States

   $ 63,625   $ 69,957   $ 85,525  

Revenue-Canada

     10,480     12,453     14,079  

Revenue-all other international sources

     19,271     27,102     28,907  
               
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Total revenue

   $ 93,376   $ 109,512   $ 128,511  
               
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​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
               

International revenue (excluding Canada) as a percent of total revenue

     21 %   25 %   22 %
Schedule of changes in the product warranty liability

 The following table presents the changes in the product warranty liability (in thousands):

 
   Years Ended December 31,  
 
   2011   2012   2013  

Balance at the beginning of the period

   $ 775   $ 1,030   $ 1,155  

Warranty costs accrued

     727     1,050     1,025  

Warranty claims

     (472 )   (925 )   (967 )
               
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Balance at the end of the period

   $ 1,030   $ 1,155   $ 1,213  
               
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Schedule of reconciliation of the numerator and denominator used in the calculation of basic and diluted net income (loss) per share

The following table presents the reconciliation of the numerator and denominator used in the calculation of basic and diluted net income (loss) per share (in thousands):

 
   Years Ended December 31,  
 
   2011   2012   2013  

Numerator:

                    

Net income (loss)

   $ (3,885 ) $ (3,723 ) $ 3,503  
               
​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
               

Denominator:

                    

Weighted average common stock outstanding for basic net income (loss) per common share

     1,923     2,360     10,609  

Effect of dilutive securities—stock options, convertible preferred stock, and warrants to purchase common stock and preferred stock

     —     —     11,654  
               
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Weighted average common shares and dilutive securities outstanding

     1,923     2,360     22,263  
               
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Schedule of anti-dilutive weighted-average common stock equivalents excluded from the calculation of diluted net income (loss) per share

The following weighted-average common stock equivalents were anti-dilutive and therefore were excluded from the calculation of diluted net income (loss) per share (in thousands):

 
   Years Ended December 31,  
 
   2011   2012   2013  

Convertible preferred stock

     15,257     15,294     —  

Options to purchase common stock

     3,953     4,317     356  

Warrants to purchase common stock

     510     541     1  

Warrants to purchase preferred stock

     194     194     —  
               
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Total

     19,914     20,346     357  
               
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​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
               
Schedule of changes in the allowance for doubtful accounts

The following table presents the changes in the allowance for doubtful accounts (in thousands):

 
   Years Ended December 31,  
 
   2011   2012   2013  

Balance at beginning of period

   $ 619   $ 651   $ 643  

Provision

     283     184     159  

Deductions

     (251 )   (192 )   (197 )
               
​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Balance at end of period

   $ 651   $ 643   $ 605  
               
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​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
               
Schedule of estimated useful lives of property and equipment

 

 

Furniture and fixtures

   2 - 5 years

Manufacturing tooling and test equipment

   2 - 3 years

Lab and warehouse equipment

   2 - 4 years

Computer equipment and software

   3 - 4 years

Marketing equipment

   2 - 3 years