v3.6.0.2
STOCKHOLDERS' EQUITY - Initial Public Offering and Conversion of Convertible Preferred Stock (Details) - USD ($)
$ / shares in Units, $ in Thousands
 1 Months Ended 12 Months Ended
Apr. 02, 2014
Apr. 30, 2014
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Mar. 25, 2016
Class of Stock [Line Items]            
Preferred stock, shares outstanding     0 0    
Proceeds from initial public offering, net of underwriting discounts   $ 80,200 $ 0 $ 0 $ 80,213  
Underwriters' discounts and commissions   $ 6,000        
Reclassification of deferred offering costs to additional paid-in capital $ 5,400          
Series A Convertible Preferred Stock            
Class of Stock [Line Items]            
Preferred stock, shares outstanding 5,680,096          
Series B Convertible Preferred Stock            
Class of Stock [Line Items]            
Preferred stock, shares outstanding 4,929,749          
Series C Convertible Preferred Stock            
Class of Stock [Line Items]            
Preferred stock, shares outstanding 9,052,344          
Series D Convertible Preferred Stock            
Class of Stock [Line Items]            
Preferred stock, shares outstanding 5,619,234          
Series E Convertible Preferred Stock            
Class of Stock [Line Items]            
Preferred stock, shares outstanding 2,946,105          
Common Stock            
Class of Stock [Line Items]            
Share price (USD per share)   $ 10.00        
Convertible preferred stock, shares converted 28,832,898          
Number of shares called by warrant 107,876         27,715
Common Stock | IPO            
Class of Stock [Line Items]            
Stock issued during the period   8,625,000        
Common Stock | Over-Allotment Option            
Class of Stock [Line Items]            
Stock issued during the period   1,125,000        
Convertible Preferred Stock            
Class of Stock [Line Items]            
Preferred stock, shares outstanding 28,227,528          
Number of shares called by warrant 103,034