Quarterly report pursuant to Section 13 or 15(d)

Leases - Additional Information (Detail)

v3.19.2
Leases - Additional Information (Detail)
$ in Millions
1 Months Ended 3 Months Ended 6 Months Ended 12 Months Ended
Feb. 15, 2017
USD ($)
ft²
May 31, 2019
Jun. 30, 2018
USD ($)
Jun. 30, 2019
USD ($)
Jun. 30, 2018
USD ($)
Dec. 31, 2018
USD ($)
Lessee Lease Description [Line Items]            
Rent expenses under operating leases     $ 0.5   $ 1.0  
South San Francisco California Lease            
Lessee Lease Description [Line Items]            
Lease expiration date       Apr. 30, 2021    
Letter of credit renewal term       12 months    
South San Francisco California Lease | Letter of Credit            
Lessee Lease Description [Line Items]            
Letter of credit maintained       $ 0.2    
Thousand Oaks California lease            
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 lease | Letter of Credit            
Lessee Lease Description [Line Items]            
Letter of credit issued, classified as long-term restricted cash $ 1.2          
Aurora Colorado lease            
Lessee Lease Description [Line Items]            
Lease expiration date   Apr. 30, 2024        
Build To Suit Lease Arrangement | Building            
Lessee Lease Description [Line Items]            
Construction in progress           $ 10.3
Capitalized interest costs during the construction period           $ 0.3