Company Information - Completion of a future currency contract (Details) $ in Millions		1 Months Ended	2 Months Ended
Dec. 31, 2020 contract	Oct. 31, 2020 USD ($)	Sep. 30, 2020 USD ($) item	Oct. 31, 2020 USD ($)
Company Information
Number of future currency contracts completed	3		2
Amount of future currency contracts completed		$ 20	$ 40	$ 60

The notional amount of forward contracts completed during the period.

No definition available.

Name:	iva_NotionalAmountOfForwardContractsCompleted
Namespace Prefix:	iva_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	duration