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Commitments and Contingencies - Additional Information (Detail) - USD ($)
$ in Millions
 1 Months Ended
Jul. 31, 2020
May 31, 2020
Nov. 30, 2019
Sep. 30, 2020
Vertex Pharmaceuticals Incorporated and Certain of its Subsidiaries [Member]        
Contingencies And Commitments [Line Items]        
Milestone payment receivable       $ 410.0
Letter of Credit [Member]        
Contingencies And Commitments [Line Items]        
Letters of credit secured by cash held in restricted depository account       16.8
Lease Arrangement [Member]        
Contingencies And Commitments [Line Items]        
Annual rental payments     $ 3.7  
Rental payments period 152 months 15 years 5 years  
Lease Arrangement [Member] | Minimum [Member]        
Contingencies And Commitments [Line Items]        
Rental payments $ 292.5 $ 40.2    
2015 Collaboration Agreement [Member] | Vertex Pharmaceuticals Incorporated and Certain of its Subsidiaries [Member]        
Contingencies And Commitments [Line Items]        
Milestone payment receivable       $ 395.0