Accounting Principles - Foreign currency transactions and Segment information (Details) € in Millions	12 Months Ended
Dec. 31, 2024 EUR (€) segment	Dec. 31, 2023 EUR (€)	Dec. 31, 2022 EUR (€)
Accounting Principles
Amount of expenses denominated in foreign currency \| €	€ 37.3	€ 46.8	€ 15.9
Foreign currency expenses as a percentage of operating expenses	33.00%	37.00%	21.00%
Number of operating segments \| segment	1

Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

No definition available.

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Namespace Prefix:	iva_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration