Summary of IPR&D Intangible Assets and Goodwill (Detail) - USD ($)
$ in Thousands
3 Months Ended 9 Months Ended 12 Months Ended
Jun. 30, 2016
Dec. 31, 2015
Sep. 30, 2016
Dec. 31, 2015
IPR&D intangible assets:        
Balance at beginning of period     $ 101,500  
Impairment of intangible asset $ (104,500) $ (89,600) (104,517)  
Balance at end of period   101,500   $ 101,500
Goodwill:        
Balance at beginning of period     59,327  
Balance at end of period   59,327 60,748 59,327
In Process Research and Development        
IPR&D intangible assets:        
Balance at beginning of period     101,500 212,900
Impairment of intangible asset $ (104,500)   (104,517) (89,557)
Change in foreign currency gains (losses)     3,017 (21,843)
Balance at end of period   101,500 0 101,500
Ethical Oncology Science, S.p.A.        
Goodwill:        
Balance at beginning of period     59,327 66,055
Change in foreign currency gains (losses)     1,421 (6,728)
Balance at end of period   $ 59,327 $ 60,748 $ 59,327