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Revenue - Summary of Information About Receivables, Contract Assets And Contract Liabilities From Contracts With Customers (Detail) - EUR (€)
€ in Thousands
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Receivables from contracts with customers [abstract]      
Trade receivables € 29,187 € 40,967 € 37,549
Contract liabilities € 23,103 € 22,099 € 15,533