XML 51 R26.htm IDEA: XBRL DOCUMENT v3.19.3
Summary of Significant Accounting Policies - Summary of Common Stock Equivalents Outstanding (Detail) - shares
9 Months Ended
Sep. 30, 2019
Sep. 30, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]    
Total potentially dilutive shares 5,175,050 5,681,326
Options to Purchase Common Stock [Member]    
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]    
Total potentially dilutive shares 5,118,280 5,676,861
Unvested Restricted Common Stock [Member]    
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]    
Total potentially dilutive shares 56,770 4,465