Quarterly report pursuant to Section 13 or 15(d)

Property and Equipment - Schedule of Property and Equipment (Detail)

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Property and Equipment - Schedule of Property and Equipment (Detail) - USD ($)
$ in Thousands
Sep. 30, 2018
Dec. 31, 2017
Property Plant And Equipment [Line Items]    
Property and equipment, gross $ 71,878 $ 45,474
Less accumulated depreciation and amortization (3,599) (1,345)
Property and equipment, net 68,279 44,129
Leasehold Improvements    
Property Plant And Equipment [Line Items]    
Property and equipment, gross 40,390 623
Construction in Progress    
Property Plant And Equipment [Line Items]    
Property and equipment, gross 14,136 40,797
Build-to-Suit Asset    
Property Plant And Equipment [Line Items]    
Property and equipment, gross 10,686 0
Lab Equipment    
Property Plant And Equipment [Line Items]    
Property and equipment, gross 2,830 2,156
Machinery Equipment    
Property Plant And Equipment [Line Items]    
Property and equipment, gross 1,410 885
Furniture and Fixtures    
Property Plant And Equipment [Line Items]    
Property and equipment, gross 1,628 536
Computer Equipment and Software    
Property Plant And Equipment [Line Items]    
Property and equipment, gross $ 798 $ 477