Annual report pursuant to Section 13 and 15(d)

Nature of Business (Details)

v3.6.0.2
Nature of Business (Details) - USD ($)
$ / shares in Units, $ in Thousands
 3 Months Ended 12 Months Ended
Jul. 06, 2016
Dec. 31, 2016
Sep. 30, 2016
Jun. 30, 2016
Mar. 31, 2016
Dec. 31, 2015
Sep. 30, 2015
Jun. 30, 2015
Mar. 31, 2015
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Initial Public Offering                        
Net proceeds                   $ 53,480    
Underwriting discounts, commissions and other offering costs                   $ 2,996 $ 620  
Common stock issued upon conversion of convertible preferred stock (in shares) 15,988,800                      
Common stock, shares authorized (in shares) 200,000,000 200,000,000       66,171,908       200,000,000 66,171,908  
Preferred stock, shares authorized (in shares) 10,000,000 10,000,000       0       10,000,000 0  
Par value, common stock (in dollars per share) $ 0.001 $ 0.001       $ 0.001       $ 0.001 $ 0.001  
Par value, preferred stock (in dollars per share) $ 0.001 $ 0.001       $ 0.001       $ 0.001 $ 0.001  
Net loss   $ 10,965 $ 14,169 $ 12,021 $ 10,588 $ 10,689 $ 8,464 $ 6,097 $ 4,568 $ 47,743 $ 29,818 $ 13,431
Accumulated deficit   101,256       $ 53,513       101,256 $ 53,513  
Cash equivalents and marketable securities   $ 83,600               $ 83,600    
Convertible Preferred Stock                        
Initial Public Offering                        
Convertible preferred stock, shares outstanding (in shares) 0                      
Common Stock                        
Initial Public Offering                        
Shares issued                   4,600,000    
Common Stock | IPO                        
Initial Public Offering                        
Shares issued 4,600,000                      
Share price $ 12.50                      
Aggregate gross proceeds $ 57,500                      
Net proceeds 49,900                      
Underwriting discounts, commissions and other offering costs $ 7,600                 $ 7,600    
Common Stock | Over-allotment                        
Initial Public Offering                        
Shares issued 600,000