XML 47 R35.htm IDEA: XBRL DOCUMENT v3.10.0.1
Fair Value Measurements, Fair Value Measurements Using Significant Unobservable Inputs (Level 3) (Details) - USD ($)
$ in Thousands
6 Months Ended
Jun. 30, 2017
Jun. 30, 2018
Dec. 31, 2017
Jan. 31, 2017
Novartis [Member]        
Novartis Future Stock Purchase [Abstract]        
Additional amount of common stock required to be purchased       $ 50,000
Fair value of potential future premium       $ 5,000
1 Percent Convertible Senior Notes [Member]        
Fair Value Measurements [Abstract]        
Interest rate on convertible senior notes 1.00% 1.00% 1.00%  
Significant Other Observable Inputs (Level 2) [Member] | 1 Percent Convertible Senior Notes [Member]        
Fair Value Measurements [Abstract]        
Fair value of convertible notes   $ 671,700    
Significant Unobservable Inputs (Level 3) [Member]        
Fair Value Measurements [Abstract]        
Financial instruments   $ 0 $ 0  
Potential Future Premium [Member]        
Unobservable Inputs (Level 3) [Roll Forward]        
Beginning balance of Level 3 instruments $ 0      
Value of the potential premium we would have received from Novartis at inception of the SPA (January 2017) 5,035      
Recurring fair value adjustment during the six months ended June 30, 2017 (1,438)      
Ending balance of Level 3 instruments $ 3,597