XML 49 R39.htm IDEA: XBRL DOCUMENT v3.7.0.1
Net loss per share (Details) - shares
3 Months Ended
Mar. 31, 2017
Mar. 31, 2016
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]    
Antidilutive securities excluded from computation of earnings per share (in shares) 3,613,410 4,299,813
Options to purchase common stock    
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]    
Antidilutive securities excluded from computation of earnings per share (in shares) 2,672,069 2,336,668
Unvested restricted common stock    
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]    
Antidilutive securities excluded from computation of earnings per share (in shares) 941,341 1,963,145