Quarterly report pursuant to Section 13 or 15(d)

Organization and Description of Business - Additional Information (Detail)

v3.19.3
Organization and Description of Business - Additional Information (Detail) - USD ($)
9 Months Ended
Sep. 30, 2019
Sep. 30, 2018
Dec. 31, 2018
Organization And Description Of Business [Line Items]      
Accumulated deficit $ (201,758,901)   $ (199,319,892)
Net cash used in operating activities $ (19,789,854) $ (19,202,063)