v3.10.0.1
Financial Risk Management and Financial Instruments - Summary of Major Security Type, Financial Assets and Liabilities that are Measured at Fair Value on Recurring Basis and Category Using Fair Value Hierarchy (Details) - EUR (€)
€ in Millions
Dec. 31, 2018
Dec. 31, 2017
Financial assets at fair value    
Total financial assets at fair value by level € 2,569 € 1,950
Financial liabilities at fair value    
Total financial liabilities at fair value by level 339 1,298
Convertible Notes    
Financial liabilities at fair value    
Total financial liabilities at fair value by level   944
Derivatives (Designated for Hedging) | Foreign Exchange Forwards    
Financial liabilities at fair value    
Total financial liabilities at fair value by level 6 5
Derivatives (Not Designated for Hedging) | Warrants    
Financial liabilities at fair value    
Total financial liabilities at fair value by level 333 346
Derivatives (Not Designated for Hedging) | Contingent Options    
Financial liabilities at fair value    
Total financial liabilities at fair value by level   3
Foreign Exchange Forwards | Derivatives (Designated for Hedging)    
Financial assets at fair value    
Total financial assets at fair value by level 6 6
Foreign Exchange Forwards | Derivatives (Not Designated for Hedging)    
Financial assets at fair value    
Total financial assets at fair value by level   2
Short Term Investments | Government Securities    
Financial assets at fair value    
Total financial assets at fair value by level 221 244
Short Term Investments | Agency Securities    
Financial assets at fair value    
Total financial assets at fair value by level 7 7
Short Term Investments | Corporate Notes    
Financial assets at fair value    
Total financial assets at fair value by level 343 330
Short Term Investments | Collateralized Reverse Purchase Agreements    
Financial assets at fair value    
Total financial assets at fair value by level 344 451
Other | Derivatives (Not Designated for Hedging)    
Financial assets at fair value    
Total financial assets at fair value by level 2  
Long Term Investment    
Financial assets at fair value    
Total financial assets at fair value by level 1,646 910
Level 1    
Financial assets at fair value    
Total financial assets at fair value by level 1,794 206
Level 1 | Short Term Investments | Government Securities    
Financial assets at fair value    
Total financial assets at fair value by level 164 206
Level 1 | Long Term Investment    
Financial assets at fair value    
Total financial assets at fair value by level 1,630  
Level 2    
Financial assets at fair value    
Total financial assets at fair value by level 757 834
Financial liabilities at fair value    
Total financial liabilities at fair value by level 6 5
Level 2 | Derivatives (Designated for Hedging) | Foreign Exchange Forwards    
Financial liabilities at fair value    
Total financial liabilities at fair value by level 6 5
Level 2 | Foreign Exchange Forwards | Derivatives (Designated for Hedging)    
Financial assets at fair value    
Total financial assets at fair value by level 6 6
Level 2 | Foreign Exchange Forwards | Derivatives (Not Designated for Hedging)    
Financial assets at fair value    
Total financial assets at fair value by level   2
Level 2 | Short Term Investments | Government Securities    
Financial assets at fair value    
Total financial assets at fair value by level 57 38
Level 2 | Short Term Investments | Agency Securities    
Financial assets at fair value    
Total financial assets at fair value by level 7 7
Level 2 | Short Term Investments | Corporate Notes    
Financial assets at fair value    
Total financial assets at fair value by level 343 330
Level 2 | Short Term Investments | Collateralized Reverse Purchase Agreements    
Financial assets at fair value    
Total financial assets at fair value by level 344 451
Level 3    
Financial assets at fair value    
Total financial assets at fair value by level 18 910
Financial liabilities at fair value    
Total financial liabilities at fair value by level 333 1,293
Level 3 | Convertible Notes    
Financial liabilities at fair value    
Total financial liabilities at fair value by level   944
Level 3 | Derivatives (Not Designated for Hedging) | Warrants    
Financial liabilities at fair value    
Total financial liabilities at fair value by level 333 346
Level 3 | Derivatives (Not Designated for Hedging) | Contingent Options    
Financial liabilities at fair value    
Total financial liabilities at fair value by level   3
Level 3 | Other | Derivatives (Not Designated for Hedging)    
Financial assets at fair value    
Total financial assets at fair value by level 2  
Level 3 | Long Term Investment    
Financial assets at fair value    
Total financial assets at fair value by level € 16 € 910