XML 150 R111.htm IDEA: XBRL DOCUMENT v3.21.1
Commitments and contingencies - Additional Information (Detail) - EUR (€)
€ in Millions
Dec. 31, 2020
Dec. 31, 2019
Collaboration Agreements [Member]    
Statements [Line Items]    
Unrecorded contingent liability € 1.6 € 1.6