Quarterly report pursuant to Section 13 or 15(d)

Significant Accounting Policies - Additional Information (Detail)

v3.19.1
Significant Accounting Policies - Additional Information (Detail) - USD ($)
3 Months Ended
Apr. 30, 2015
Mar. 31, 2019
Mar. 31, 2018
Summary Of Significant Accounting Policies [Line Items]      
Research and development expense, total   $ 6,800,678 $ 8,721,552
Liability for unrecognized tax benefits   0  
Interest or penalties for uncertain tax positions   $ 0 $ 0
Antidilutive securities excluded from computation of earnings per share, amount   7,601,654 7,420,048
Employee Stock Purchase Plan [Member]      
Summary Of Significant Accounting Policies [Line Items]      
Common stock purchase price discount percentage 85.00% 15.00%