Subsequent Events (Narrative) (Details) (Subsequent event, USD $)
In Millions, unless otherwise specified
1 Months Ended
Apr. 30, 2015
Quanticel Pharmaceuticals  
Subsequent Event [Line Items]  
Payments for acquisition of business $ 100
Development milestone | Quanticel Pharmaceuticals  
Subsequent Event [Line Items]  
Potential contingent consideration 385
Strategic collaboration agreement | MedImmune | MEDI4736  
Subsequent Event [Line Items]  
Milestone payment, payable $ 450
Percentage of responsible costs 7500.00%
Royalty rate, percentage of worldwide sales 7000.00%
Royalty rate. decrease 5000.00%
Royalty rate percentage, decrease period 4 years