Collaboration Agreement - Additional Information (Detail) - Janssen Pharmaceuticals Inc [Member] - Collaboration Agreement [Member]	12 Months Ended
	Dec. 31, 2018 USD ($)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Deferred research funding	$ 658,667
Deferred research funding, amortization period	8 months
Research and Development Expenses [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Amortized of deferred research funding	$ 224,576
Other Current Liabilities [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Deferred research funding	$ 434,091