XML 154 R115.htm IDEA: XBRL DOCUMENT v3.21.1
Related party disclosures - Summary of Compensation for the Supervisory Board (Parenthetical) (Detail) - EUR (€)
€ in Millions
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Disclosure of amounts incurred by entity for provision of key management personnel services provided by separate management entities [abstract]      
Key management personnel compensation, short-term employee benefits € 2.7 € 0.4 € 0.5