Financial Risk Management and Financial Instruments - Summary of Changes in Investment in TME (Details) - EUR (€) € in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2019 |
Dec. 31, 2018 |
Dec. 31, 2017 |
|
| Disclosure Of Financial Risk Management And Financial Instruments [Line Items] | |||
| At January 1 | € 1,646 | ||
| Equity issued in exchange for long term investment | € (910) | ||
| At December 31 | 1,497 | € 1,646 | |
| TME | |||
| Disclosure Of Financial Risk Management And Financial Instruments [Line Items] | |||
| At January 1 | 1,630 | 910 | |
| Equity issued in exchange for long term investment | 910 | ||
| Changes in fair value recorded in other comprehensive loss | (149) | 720 | |
| At December 31 | € 1,481 | € 1,630 | € 910 |