Related Parties - Additional Information (Detail) - USD ($)
1 Months Ended 12 Months Ended
Dec. 03, 2014
Sep. 30, 2014
Dec. 31, 2015
Dec. 31, 2014
Jun. 30, 2012
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]          
Net sales     $ 0 $ 0  
IPO Stock purchased, value       56,539,000  
Accrued expenses due to Intrexon     $ 1,546,000 7,000  
Intrexon [Member]          
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]          
Collaboration Agreement cancellation notification     90 days    
Collaboration Agreement cancellation with material breach that cannot be remedied     60 days    
Common stock to be purchased under equity purchase commitment   $ 15,000,000      
Shares issued upon conversion 918,206        
IPO Stock purchased, value $ 19,496,000        
IPO Stock purchased, shares 1,772,364        
Accrued expenses due to Intrexon     $ 1,546,000    
Intrexon [Member] | Investigational New Drug (IND) Filing Milestone Event [Member]          
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]          
Milestone payable   500,000      
Intrexon [Member] | IND Acceptance Milestone Event [Member]          
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]          
Milestone payable   2,500,000      
Intrexon [Member] | Phase III Milestone Event [Member]          
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]          
Milestone payable   3,000,000      
Intrexon [Member] | Approval Milestone Event [Member]          
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]          
Milestone payable   5,000,000      
Intrexon [Member] | Approval Amendment Milestone Event [Member]          
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]          
Milestone payable   1,000,000      
Intrexon [Member] | Cumulative Sales Milestones One [Member]          
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]          
Milestone payable   5,000,000      
Net sales   300,000,000      
Intrexon [Member] | Cumulative Sales Milestones Two [Member]          
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]          
Milestone payable   7,500,000      
Net sales   650,000,000      
Intrexon [Member] | Cumulative Sales Milestones Three [Member]          
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]          
Milestone payable   10,000,000      
Net sales   1,000,000,000      
Intrexon [Member] | Promissory Note [Member]          
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]          
Promissory note issued as up-front fee   $ 10,000,000      
Shares issued upon conversion 918,206        
Purpose, Co. [Member]          
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]          
Reimbursement for development cost, amount         $ 250,000
Reimbursement for development cost, paid     187,000 173,000  
Research and Development [Member] | Intrexon [Member]          
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]          
Research and development expense from transaction with Intrexon     $ 3,100,000 $ 14,000