Quarterly report pursuant to Section 13 or 15(d)

Summary of Significant Accounting Policies - Additional Information (Detail)

v3.8.0.1
Summary of Significant Accounting Policies - Additional Information (Detail)
1 Months Ended 3 Months Ended 9 Months Ended
Sep. 06, 2017
USD ($)
ft²
Options
Sep. 30, 2017
USD ($)
Sep. 30, 2017
USD ($)
Sep. 30, 2016
USD ($)
Sep. 30, 2017
USD ($)
Sep. 30, 2016
USD ($)
Dec. 31, 2016
USD ($)
Significant Accounting Policies [Line Items]              
Trade accounts receivable   $ 0 $ 0   $ 0   $ 110,000
Allowance for doubtful accounts   $ 0 0   0    
Sale-leaseback transaction date Sep. 06, 2017            
Lease term 20 years 20 years          
Number of lease extension options | Options 4            
Extension term of lease agreement 5 years            
Cash received upon sale of land and other improvements to third party $ 7,000,000            
Annual base rent 1,480,000       1,480,000    
Annual base rent expense $ 490,000       $ 490,000    
Percentage of annual base rent 8.00%       8.00%    
Minimum net worth required $ 300,000,000            
Assets under construction   $ 13,340,000 13,340,000   $ 13,340,000   11,726,000
Finance obligation   7,934,000 7,934,000   7,934,000    
Impairment of long-lived assets     0 $ 0 0 $ 0  
Fair value movements between Level 2 and Level 3         0 0  
Research and development expense     6,438,000 1,236,000 9,157,000 3,912,000  
Asset Under Construction [Member]              
Significant Accounting Policies [Line Items]              
Assets under construction   1,374,000 1,374,000   1,374,000   $ 37,000
Corporate Headquarters [Member]              
Significant Accounting Policies [Line Items]              
Office and lab building area | ft² 40,000            
Level 3 [Member]              
Significant Accounting Policies [Line Items]              
Financial instruments classified as Level 3   $ 0 0 0 0 0  
Related-party In-licensing [Member]              
Significant Accounting Policies [Line Items]              
Research and development expense     4,000 10,000 31,000 33,000  
Third-party In-licensing [Member]              
Significant Accounting Policies [Line Items]              
Research and development expense     $ 3,000 $ 46,000 $ 122,000 $ 385,000