Quarterly report pursuant to Section 13 or 15(d)

Nature of Business (Details)

v3.5.0.2
Nature of Business (Details) - USD ($)
$ / shares in Units, $ in Thousands
 3 Months Ended 9 Months Ended 12 Months Ended
Jul. 06, 2016
Sep. 30, 2016
Sep. 30, 2015
Sep. 30, 2016
Sep. 30, 2015
Dec. 31, 2015
Dec. 31, 2014
Jul. 07, 2016
Initial Public Offering                
Net proceeds       $ 50,455        
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   200,000,000   66,171,908    
Preferred stock, shares authorized (in shares) 10,000,000 10,000,000   10,000,000   0    
Par value, common stock (in dollars per share) $ 0.001 $ 0.001   $ 0.001   $ 0.001    
Par value, preferred stock (in dollars per share)   $ 0.001   $ 0.001   $ 0.001    
Net loss   $ 14,169 $ 8,464 $ 36,778 $ 19,129 $ 29,800 $ 13,400  
Accumulated deficit   $ 90,291   $ 90,291   $ 53,513    
Convertible Preferred Stock                
Initial Public Offering                
Convertible preferred stock, shares outstanding (in shares)               0
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              
Common Stock | Over-allotment                
Initial Public Offering                
Shares issued 600,000