Leases - Additional Information (Detail)		1 Months Ended			12 Months Ended
	Jun. 30, 2018 ft²	Dec. 31, 2020 USD ($) ft²	Oct. 31, 2020 USD ($) ft²	May 31, 2019 ft²	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Lessee Lease Description [Line Items]
Tenant improvement allowance					$ 15,700,000
Amount form letter of credit		$ 1,472,000			$ 1,472,000	$ 1,472,000	$ 1,472,000
Lease expiration year					2029
Operating lease, renewal period					10 years
Operating lease term					The lease expires in 2029 with an option to renew for a period of ten years.
Operating sublease, impairment charges					$ 0	238,000	1,158,000
Weighted average remaining lease term for operating leases					7 years 2 months 12 days
Weighted average discount rate for operating leases					8.50%
Cash paid for amounts included In measurement of lease liabilities					$ 7,900	$ 6,900	$ 3,200
Offices and Laboratory Facilities | South San Francisco
Lessee Lease Description [Line Items]
Area under lease | ft²	105,000	23,600
Area under sublease | ft²				25,000
Sublease expiration month and year					2021-11
Operating sublease, existence of option to extend					true
Ongoing loss over sublease period					$ 0
Offices and Laboratory Facilities | South San Francisco | General and Administrative Expense
Lessee Lease Description [Line Items]
Operating sublease, impairment charges					$ 1,200,000
Offices and Laboratory Facilities | South San Francisco
Lessee Lease Description [Line Items]
Tenant improvement allowance			$ 400,000
Area of property | ft²			18,700
Lease, description					In October 2020, the Company signed a lease agreement to lease approximately 18,700 square feet of office and laboratory space in Newark, California. The lease term ends on February 6, 2028 with an option to extend for an additional five years. The landlord is obligated to pay for up to $0.4 million of tenant improvements.
Lease expiration date			Feb. 06, 2028
Extend for an additional lease term			5 years