Quarterly report pursuant to Section 13 or 15(d)

Leases - Additional Information (Detail)

v3.19.3
Leases - Additional Information (Detail)
$ in Millions
1 Months Ended 3 Months Ended 9 Months Ended 12 Months Ended
Feb. 15, 2017
USD ($)
ft²
May 31, 2019
Sep. 30, 2018
USD ($)
Sep. 30, 2019
USD ($)
Sep. 30, 2018
USD ($)
Dec. 31, 2018
USD ($)
Lessee Lease Description [Line Items]            
Rent expenses under operating leases     $ 0.6   $ 1.6  
Building | Build To Suit Lease Arrangement            
Lessee Lease Description [Line Items]            
Build-to-suit asset           $ 10.3
Capitalized interest costs during the construction period           $ 0.3
South San Francisco California            
Lessee Lease Description [Line Items]            
Lease expiration date       Apr. 30, 2021    
Letter of credit renewal term       12 months    
South San Francisco California | Letter of Credit            
Lessee Lease Description [Line Items]            
Letter of credit maintained       $ 0.2    
Thousand Oaks California            
Lessee Lease Description [Line Items]            
Lease expiration date       Feb. 28, 2026    
Lease agreement area of office, lab and cellular therapy manufacturing space | ft² 90,580          
Lease commencement date Feb. 15, 2018          
Lease initial term 15 years          
Contractual obligations $ 16.4          
Lease extension term, option one 10 years          
Lease extension term, option two 9 years          
Thousand Oaks California | Letter of Credit            
Lessee Lease Description [Line Items]            
Letter of credit issued, classified as long-term restricted cash $ 1.2          
Aurora Colorado            
Lessee Lease Description [Line Items]            
Lease expiration date   Apr. 30, 2024