EOS Acquisition - Additional Information (Detail)
3 Months Ended
Nov. 19, 2013
USD ($)
Jun. 30, 2016
USD ($)
Sep. 30, 2016
USD ($)
Dec. 31, 2015
USD ($)
Nov. 19, 2013
EUR (€)
Business Acquisition [Line Items]          
Reduction in fair value of contingent purchase consideration liability   $ 25,500,000      
Contingent purchase consideration     $ 0 $ 24,661,000  
Ethical Oncology Science, S.p.A.          
Business Acquisition [Line Items]          
Business acquisition cash payments made on acquisition $ 11,800,000        
Future maximum contingent milestone payments 193,500,000        
Reduction in fair value of contingent purchase consideration liability   $ 25,500,000      
Contingent purchase consideration     $ 0 $ 24,700,000  
Ethical Oncology Science, S.p.A. | Regulatory and Sales Milestones          
Business Acquisition [Line Items]          
Future maximum contingent milestone payments 65,000,000       € 115,000,000
Future minimum potential contingent milestone payments 0       € 0
Ethical Oncology Science, S.p.A. | Common Stock          
Business Acquisition [Line Items]          
Business acquisition, common stock issued at acquisition date $ 173,700,000