Quarterly report pursuant to Section 13 or 15(d)

Organization and Description of Business - Additional Information (Detail)

v3.19.1
Organization and Description of Business - Additional Information (Detail) - USD ($)
3 Months Ended
Mar. 31, 2019
Mar. 31, 2018
Dec. 31, 2018
Organization And Description Of Business [Line Items]      
Accumulated deficit $ (187,732,877)   $ (199,319,892)
Net cash used in operating activities $ (7,324,726) $ (6,810,258)