Convertible Preferred Stock (Details) - USD ($)
$ / shares in Units, $ in Thousands
12 Months Ended
Dec. 31, 2015
Dec. 31, 2015
Mar. 11, 2015
Dec. 31, 2014
Dec. 31, 2013
Convertible Preferred Stock          
Number of Shares Authorized     14,951,626    
Number of Shares Outstanding     14,848,824    
Increase (Decrease) in Temporary Equity [Roll Forward]          
Balance of convertible preferred stock $ 25,476 $ 0   $ 25,476 $ 25,476
Balance, beginning of period 25,476        
Conversion to common stock upon IPO (25,476)        
Balance, end of period 0        
Series A convertible preferred stock          
Convertible Preferred Stock          
Number of Shares Authorized   0 2,486,507 2,486,507  
Number of Shares Outstanding   0 2,383,745 2,383,745  
Original Issue and Conversion Price per Share (in usd per share)     $ 0.582    
Increase (Decrease) in Temporary Equity [Roll Forward]          
Balance of convertible preferred stock 1,387 $ 0   $ 1,387 1,387
Balance, beginning of period 1,387        
Conversion to common stock upon IPO (1,387)        
Balance, end of period 0        
Series B convertible preferred stock          
Convertible Preferred Stock          
Number of Shares Authorized   0 3,649,368 3,649,368  
Number of Shares Outstanding   0 3,649,368 3,649,368  
Original Issue and Conversion Price per Share (in usd per share)     $ 0.84656    
Increase (Decrease) in Temporary Equity [Roll Forward]          
Balance of convertible preferred stock 3,089 $ 0   $ 3,089 3,089
Balance, beginning of period 3,089        
Conversion to common stock upon IPO (3,089)        
Balance, end of period 0        
Series C convertible preferred stock          
Convertible Preferred Stock          
Number of Shares Authorized   0 5,406,501 5,406,501  
Number of Shares Outstanding   0 5,406,501 5,406,501  
Original Issue and Conversion Price per Share (in usd per share)     $ 1.4798    
Increase (Decrease) in Temporary Equity [Roll Forward]          
Balance of convertible preferred stock 8,000 $ 0   $ 8,000 8,000
Balance, beginning of period 8,000        
Conversion to common stock upon IPO (8,000)        
Balance, end of period 0        
Series D convertible preferred stock          
Convertible Preferred Stock          
Number of Shares Authorized   0 3,409,250 3,409,250  
Number of Shares Outstanding   0 3,409,210 3,409,210  
Original Issue and Conversion Price per Share (in usd per share)     $ 3.8132    
Increase (Decrease) in Temporary Equity [Roll Forward]          
Balance of convertible preferred stock 13,000 $ 0   $ 13,000 $ 13,000
Balance, beginning of period 13,000        
Conversion to common stock upon IPO (13,000)        
Balance, end of period $ 0        
IPO          
Convertible Preferred Stock          
Shares issued upon conversion     14,848,824