Share-based Payments - Summary of Impact of Changes on Stock Options Expense for Options Granted (Details) - EUR (€) € in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2018 |
Dec. 31, 2017 |
Dec. 31, 2016 |
|
| Disclosure Of Share Based Payments [Line Items] | |||
| Share-based payments | € 88 | € 65 | € 53 |
| Volatility Decreased by 10% | |||
| Stock option expense increase (decrease) under the following assumption changes | |||
| Volatility increase (decrease) by 10% | (11) | ||
| Volatility Increase by 10% | |||
| Stock option expense increase (decrease) under the following assumption changes | |||
| Volatility increase (decrease) by 10% | 11 | ||
| Expected Life Decrease by 1 Year | |||
| Stock option expense increase (decrease) under the following assumption changes | |||
| Expected life decrease by 1 year | (7) | ||
| Expected Life Increase by 1 Year | |||
| Stock option expense increase (decrease) under the following assumption changes | |||
| Expected life decrease by 1 year | 6 | ||
| Options Granted in 2018 | |||
| Disclosure Of Share Based Payments [Line Items] | |||
| Share-based payments | € 46 | ||