Quarterly report pursuant to Section 13 or 15(d)

Milestones and Sponsored Research Agreements - Additional Information (Detail)

v3.4.0.3
Milestones and Sponsored Research Agreements - Additional Information (Detail) - USD ($)
$ in Thousands
 1 Months Ended 3 Months Ended
Mar. 31, 2016
Feb. 29, 2016
Mar. 31, 2016
Mar. 31, 2015
Milestones and Sponsored Research Agreements [Line Items]        
Research And Development Expense     $ 7,736 $ 1,642
Terms Of Clinical Reasearch Support Agreement   Under the terms of the agreement an additional $1.0 million is due when certain clinical milestones are achieved using the initial $1.0 million. An additional $2.4 million is due upon the achievement of certain clinical and other milestones. The agreement expires upon the delivery of a final study report or May 31, 2018 unless terminated earlier.    
Mustang Bio, Inc [Member]        
Milestones and Sponsored Research Agreements [Line Items]        
Research and Development Arrangement, Contract to Perform for Others, Compensation Earned     2,000  
Research And Development Expense     500  
UCLB [Member]        
Milestones and Sponsored Research Agreements [Line Items]        
Research and Development Expense Payable, Milestone Payment $ 22,000   22,000  
Milestone Payments     400  
Payment of Upfront Fees     $ 100  
UCLB [Member] | Maximum [Member]        
Milestones and Sponsored Research Agreements [Line Items]        
Royalty Percentage     5.00%  
UCLB [Member] | Minimum [Member]        
Milestones and Sponsored Research Agreements [Line Items]        
Royalty Percentage     3.00%  
City Of Hope [Member]        
Milestones and Sponsored Research Agreements [Line Items]        
Payments to Acquire in Process Research and Development 1,000 $ 1,000    
Research and Development Expense Payable, Milestone Payment $ 2,000 $ 3,400 $ 2,000