Accrued Expenses - Schedule of Accrued Expenses (Detail) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Accrued Liabilities And Other Liabilities [Abstract]
Accrued professional services	$ 552,619	$ 835,326
Accrued payroll and employee benefits	1,257,191	909,455
Accrued interest	1,192	536
Accrued construction costs		328,384
Accrued research and development	2,076,704	1,551,556
Deferred Revenue	19,753	19,753
Deferred rent	175,490	15,914
Accrued expenses	$ 4,082,949	$ 3,660,924