Quarterly report pursuant to Section 13 or 15(d)

Organization and Description of Business - Additional Information (Detail)

v3.19.2
Organization and Description of Business - Additional Information (Detail) - USD ($)
6 Months Ended
Jun. 30, 2019
Jun. 30, 2018
Dec. 31, 2018
Organization And Description Of Business [Line Items]      
Accumulated deficit $ (196,399,783)   $ (199,319,892)
Net cash used in operating activities $ (16,114,304) $ (13,201,211)