Asset Acquisition - Additional Information (Detail) - USD ($)		12 Months Ended
	Oct. 05, 2018	Dec. 31, 2018
Acquisition Date [Line Items]
Fair value of asset acquisition in process R&D	$ 2,990,250
Contingent milestone payment		$ 21,000,000
Vector Neurosciences Inc [Member]
Acquisition Date [Line Items]
Number of shares issued as initial merger consideration	225,000
Agreement date	Oct. 05, 2018
Period of shares issued as initial merger consideration	18 months
Vector Neurosciences Inc [Member] | Maximum [Member]
Acquisition Date [Line Items]
Value of stockholders additional ordinary shares	$ 21,000,000
Vector Neurosciences Inc [Member] | Issued at Closing of Merger [Member]
Acquisition Date [Line Items]
Number of shares issued as initial merger consideration	202,500
Vector Neurosciences Inc [Member] | Issued Following Closing of Merger [Member]
Acquisition Date [Line Items]
Number of shares issued as initial merger consideration	22,500