Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements - Information about Company's Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail)

v3.19.1
Fair Value Measurements - Information about Company's Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($)
Mar. 31, 2019
Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Marketable securities $ 16,267,629 $ 22,131,936
Warrant liabilities (2,982,034) (20,781,663)
Fair Value, Measurements, Recurring [Member] | Level 1 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash equivalents 4,898,991 6,850,772
Marketable securities 16,267,629 22,131,936
Total assets (liabilities) 21,166,620 28,982,708
Fair Value, Measurements, Recurring [Member] | Level 3 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Warrant liabilities 2,982,034 20,781,663
Total assets (liabilities) $ 2,982,034 $ 20,781,663