Commitments - Additional Information (Detail)	6 Months Ended
	Jun. 30, 2020 USD ($) ft²	Jun. 30, 2019 USD ($)
Operating Leased Assets [Line Items]
Expiration date	2031-02
Initial annual base rent expense	$ 6,500,000
Incremental percentage of annual lease rent	3.00%
Operating lease contract	10 years
Tenant improvement allowance	$ 15,400,000
Proceeds from Additional Tenant Allowance	$ 4,800,000
Operating lease, option to extend	option to extend the lease for five years
Additional tenant improvement allowance	7.00%
Operating lease new facility commence	2020-06
Operating Lease, Payments	$ 790,000	$ 565,000
Operating Lease, Weighted Average Remaining Lease Term	10 years 4 months 24 days
Operating Lease, Weighted Average Discount Rate, Percent	9.50%
Letter of Credit [Member]
Operating Leased Assets [Line Items]
Security deposit	$ 1,100,000
San Carlos California [Member]
Operating Leased Assets [Line Items]
Area of Land | ft²	96,463
Discounted lease	Following a six month period of discounted rent
Third Amendment May 2019 [Member]
Operating Leased Assets [Line Items]
Expiration date	2021-04