Provisions for Retirement Benefit Obligations - Breakdown of expense recognized for the period (Details) - EUR (€) € in Thousands	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Provisions for Retirement Benefit Obligations
Service cost for the period	€ (224)	€ (202)	€ (195)
Interest cost for the period	(5)	(8)	(16)
Benefits for the period	29		53
Plan curtailments and modifications			157
Total	€ (200)	€ (209)	€ (1)

The expense of employee service in the current period arising from defined benefit plans. [Refer: Post-employment benefit expense in profit or loss, defined benefit plans] [Contrast: Increase in net defined benefit liability (asset) resulting from current service cost]

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 19
-IssueDate 2021-01-01
-Paragraph 135
-Subparagraph b
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=19&code=ifrs-tx-2021-en-r&anchor=para_135_b&doctype=Standard
-URIDate 2021-03-24

+ Details

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Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- References

No definition available.

+ Details

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Namespace Prefix:	ifrs-full_
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Period Type:	duration

- Definition

The amount of interest expense arising from defined benefit plans. [Refer: Interest expense; Post-employment benefit expense in profit or loss, defined benefit plans] [Contrast: Increase (decrease) in net defined benefit liability (asset) resulting from interest expense (income)]

+ References

+ Details

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Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount of expense (income) resulting from past service cost and losses (gains) arising from settlements. [Refer: Post-employment benefit expense in profit or loss, defined benefit plans; Past service cost, defined benefit plans] [Contrast: Increase (decrease) in net defined benefit liability (asset) resulting from past service cost and losses (gains) arising from settlements]

+ References

+ Details

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Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount of post-employment benefit expense included in profit or loss relating to defined benefit plans. [Refer: Profit (loss); Defined benefit plans [member]] [Contrast: Increase (decrease) in net defined benefit liability (asset) resulting from expense (income) in profit or loss]

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 19
-IssueDate 2021-01-01
-Paragraph 5
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=19&code=ifrs-tx-2021-en-r&anchor=para_5&doctype=Standard
-URIDate 2021-03-24

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 19
-IssueDate 2021-01-01
-Paragraph 135
-Subparagraph b
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=19&code=ifrs-tx-2021-en-r&anchor=para_135_b&doctype=Standard
-URIDate 2021-03-24

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of gain (loss) recognized for plan curtailments and modifications related to defined benefit plan.

+ References

No definition available.

+ Details

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