Leases - Schedule of Leases (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Assets
Operating lease assets	$ 5,598		$ 5,598		$ 1,963
Total leased assets	5,598		5,598		1,963
Liabilities
Current - Operating	623		623		611
Noncurrent - Operating	5,220		5,220		1,497
Total leased liabilities	5,843		5,843		$ 2,108
Lease Cost
Net lease cost	$ 367	$ 210	$ 659	$ 418
Lease Term and Discount Rate
Weighted-average remaining lease term (years)	5 years 10 months 24 days		5 years 10 months 24 days		2 years 7 months 6 days
Weighted-average discount rate	6.50%		6.50%		7.00%
SG&A and R&D Expenses [Member]
Lease Cost
Operating lease cost	$ 261	177	$ 484	352
Sublease income	(11)	(12)	(22)	(27)
R&D Expenses [Member]
Lease Cost
Short term lease cost	114	$ 45	194	93
SG&A Expenses [Member]
Lease Cost
Short term lease cost	$ 3		$ 3	$ 0