Leases - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended
	Jul. 31, 2019	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Operating Leased Assets [Line Items]
Existence of option to extend				true
Option to extend, description				Certain leases include one or more options to renew, exercised at the Company’s sole discretion, with renewal terms that can extend the lease from one year to five years.
Cash payments for operating leases		$ 1,647		$ 4,935
Weighted average remaining lease term		4 years 1 month 13 days		4 years 1 month 13 days
Weighted average incremental borrowing rate		11.00%		11.00%
Office, Laboratory and Manufacturing Space [Member]
Operating Leased Assets [Line Items]
Rental expense related to office and laboratory space		$ 1,096	$ 1,093	$ 3,299	$ 3,299
Sublease Agreement [Member]
Operating Leased Assets [Line Items]
Lessee, operating sublease, existence of option to extend	false
Lessee, operating sublease, option to extend, description				The term of the sublease agreement commenced in July 2019 and ends on the last day of the 24th calendar month following commencement, with no option to extend.
Sublease annual rent first year	$ 1,200
Sublease annual rent second year	$ 1,300
Minimum [Member]
Operating Leased Assets [Line Items]
Operating lease, remaining term				1 year
Lease extension period		1 year		1 year
Maximum [Member]
Operating Leased Assets [Line Items]
Operating lease, remaining term				5 years
Lease extension period		5 years		5 years