Leases - Schedule of Components of Lease Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Leases [Abstract]
Fixed operating lease cost	$ 537	$ 413	$ 1,554	$ 847
Short-term lease costs	0	40	42	116
Total lease expense	537	453	1,596	963
Right-of-use asset obtained in exchange for operating lease liabilities	0	4,646	1,343	4,646
Operating cash flows from operating leases	314	479	917	963
Sublease income	$ 49	$ 49	$ 147	$ 146
Weighted-average remaining lease term-operating leases (in years)	5 years 2 months 12 days		5 years 2 months 12 days
Weighted-average discount rate-operating leases	11.30%		11.30%