Interim condensed consolidated statement of income (loss) (Parenthetical) € in Millions	6 Months Ended
Jun. 30, 2026 EUR (€)
Profit or loss [abstract]
Dilution gain on investment in associate	€ 0.3

The amount of dilution gain (loss) of associates accounted for using the equity method.

No definition available.

Name:	iva_DilutionGainLossOfAssociatesAccountedForUsingEquityMethod
Namespace Prefix:	iva_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration