Quarterly report pursuant to Section 13 or 15(d)

Marketable Securities - Additional Information (Detail)

v3.19.3
Marketable Securities - Additional Information (Detail)
12 Months Ended
Dec. 31, 2018
USD ($)
Security
Sep. 30, 2019
USD ($)
Marketable Securities [Abstract]    
Maturity period classified current investments less than one year  
Number of securities in unrealized loss position for less than one year | Security 21  
Aggregate fair value of debt securities $ 18,551,296  
Marketable securities   $ 0