Summary of Significant Accounting Policies - Schedule of Property and Equipment (Detail)	9 Months Ended
	Sep. 30, 2019
Office furniture
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Computer equipment
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Laboratory equipment | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Laboratory equipment | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	10 years
Leasehold improvements
Property, Plant and Equipment [Line Items]
Estimated useful life	10 years
Estimated useful life	Shorter of lease term or 10 years