Net exchange rate gains/(losses) - Schedule of Net Exchange Rate Gains (Losses) (Detail) - EUR (€) € in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disclosure Of Net Exchange Rate Gains Losses [Abstract]
Net realised gains/(losses) on derivative instruments	€ 317	€ (737)	€ (906)
Net realised gains/(losses) on trade receivables and payables	(2,793)	1,600	3,353
Total net realised gains/(losses) (a)	(2,476)	863	2,447
Net unrealised gains/(losses) on derivative instruments	486	(638)	(57)
Net unrealised gains/(losses) on trade receivables and payables	(1,507)	(531)	(5,437)
Net unrealised gains/(losses) on non-monetary assets	(404)	(2,034)	(867)
Total net unrealised gains/(losses) (b)	(1,425)	(3,203)	(6,361)
Total realised and unrealised exchange rate gains/(losses) (a+b)	€ (3,901)	€ (2,340)	€ (3,914)

The amount of exchange differences recognised in profit or loss that arise from foreign currency transactions, excluding those arising on financial instruments measured at fair value through profit or loss in accordance with IFRS 9. [Refer: At fair value [member]; Financial instruments, class [member]]

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Name IAS
-Number 7
-IssueDate 2020-01-01
-Section A Statement of cash flows for an entity other than a financial institution
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=7&code=ifrs-tx-2020-en-r&doctype=Illustrative%20Examples&dita_xref=IAS07_IE_A_TI
-URIDate 2020-01-01

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 21
-IssueDate 2020-01-01
-Paragraph 52
-Subparagraph a
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-URIDate 2020-01-01

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