XML 210 R165.htm IDEA: XBRL DOCUMENT v3.10.0.1
Share-based compensation - Options on EUR-denominated listed share (Detail) - Euro [Member]
12 Months Ended
Dec. 31, 2018
EUR (€)
Dec. 31, 2017
EUR (€)
Share-based compensation - Text Details (Detail) [Line Items]    
Number of share options outstanding in share-based payment arrangement 1,648,720  
Option plans [Member]    
Share-based compensation - Text Details (Detail) [Line Items]    
Number of share options outstanding in share-based payment arrangement 1,648,720 2,772,210
Weighted average exercise price of share options outstanding in share-based payment arrangement € 18.90 € 19.49
Number of share options exercised in share-based payment arrangement 1,024,063  
Weighted average exercise price of share options exercised in share-based payment arrangement € 20.14  
Number of share options expired in share-based payment arrangement 99,427  
Weighted average exercise price of share options expired in share-based payment arrangement € 22.52  
Number of share options exercisable in share-based payment arrangement 1,648,720  
Weighted average exercise price of share options exercisable in share-based payment arrangement € 18.90