Annual report pursuant to Section 13 and 15(d)

Commitments and Contingencies - Additional Information (Details)

v3.20.4
Commitments and Contingencies - Additional Information (Details)
1 Months Ended 12 Months Ended
Sep. 30, 2020
USD ($)
ft²
May 31, 2016
Mar. 31, 2015
Dec. 31, 2014
Aug. 31, 2012
May 31, 2011
Dec. 31, 2020
USD ($)
Dec. 31, 2019
USD ($)
Dec. 31, 2018
USD ($)
Loss Contingencies [Line Items]                  
Rent expense             $ 4,700 $ 3,600 $ 3,600
Sublease Agreement                  
Loss Contingencies [Line Items]                  
Security deposit $ 900,000                
Sublease Agreement | Five Prime Therapeutics, Inc. (the “Sublessor”)                  
Loss Contingencies [Line Items]                  
Area of Sublease Premises | ft² 115,466                
Operating lease, expense $ 1,100,000                
Lease expiration Date Dec. 31, 2027                
Aggregate estimated base rent payments due, sublease $ 45,500,000                
Lease base rent abatement $ 5,200,000                
Second Facility In South San Francisco                  
Loss Contingencies [Line Items]                  
Lessee operating lease fixed rental payment period   2021-11              
South San Francisco Facility                  
Loss Contingencies [Line Items]                  
Lessee operating lease fixed rental payment period   2021-11              
San Carlos California Facility | California                  
Loss Contingencies [Line Items]                  
Lessee operating lease fixed rental payment period         2016-07        
Initial operating lease agreement period           2011-05      
Lease, extended lease term       2021-07          
Description of options to extend the lease term             two three-year options to extend the lease term    
Option to extend lease term       2027-07          
Second Facility in San Carlos | California                  
Loss Contingencies [Line Items]                  
Lessee operating lease fixed rental payment period     2021-06            
Initial operating lease agreement period     2015-03            
Description of options to extend the lease term             two three-year options to extend the lease term    
Option to extend lease term     2027-06            
Initial Premises | Sublease Agreement | Five Prime Therapeutics, Inc. (the “Sublessor”)                  
Loss Contingencies [Line Items]                  
Area of Sublease Premises | ft² 85,755                
Expansion Premises | Sublease Agreement | Five Prime Therapeutics, Inc. (the “Sublessor”)                  
Loss Contingencies [Line Items]                  
Area of Sublease Premises | ft² 29,711