Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Note Expiry date 2027-01-01
-Name IAS
-Number 1
-IssueDate 2025-01-01
-Paragraph 82
-Subparagraph b
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2025-en-b&anchor=para_82_b&doctype=Standard
-URIDate 2025-03-27

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

- References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Note Expiry date 2027-01-01
-Name IAS
-Number 1
-IssueDate 2025-01-01
-Paragraph 85
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2025-en-b&anchor=para_85&doctype=Standard
-URIDate 2025-03-27

+ Details

Name:	ifrs-full_FinanceIncome
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- References

+ Details

Name:	ifrs-full_FinanceIncomeCost
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 21
-IssueDate 2025-01-01
-Paragraph 52
-Subparagraph a
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=21&code=ifrs-tx-2025-en-r&anchor=para_52_a&doctype=Standard
-URIDate 2025-03-27

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2027-01-01
-Name IFRS
-Number 19
-IssueDate 2025-01-01
-Paragraph 218
-Subparagraph a
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=19&code=ifrs-tx-2025-en-r&anchor=para_218_a&doctype=Standard
-URIDate 2025-03-27

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2027-01-01
-Name IFRS
-Number 19
-IssueDate 2025-01-01
-Paragraph 218
-Subparagraph a
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=19&code=ifrs-tx-2025-en-r&anchor=para_218_a&doctype=Standard
-URIDate 2025-03-27

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Note Expiry date 2027-01-01
-Name IAS
-Number 1
-IssueDate 2025-01-01
-Paragraph 35
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2025-en-b&anchor=para_35&doctype=Standard
-URIDate 2025-03-27

+ Details

Name:	ifrs-full_ForeignExchangeGain
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- References

+ Details

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

- Definition

The gains resulting from change in the fair value of derivatives recognised in profit or loss. [Refer: Derivatives [member]]

+ References

+ Details

Name:	ifrs-full_GainsOnChangeInFairValueOfDerivatives
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The amount of expense arising from interest.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 8
-IssueDate 2025-01-01
-Paragraph 28
-Subparagraph e
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=8&code=ifrs-tx-2025-en-r&anchor=para_28_e&doctype=Standard
-URIDate 2025-03-27

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 12
-IssueDate 2025-01-01
-Paragraph B13
-Subparagraph f
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=12&code=ifrs-tx-2025-en-r&anchor=para_B13_f&doctype=Appendix&subtype=B
-URIDate 2025-03-27

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 8
-IssueDate 2025-01-01
-Paragraph 23
-Subparagraph d
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=8&code=ifrs-tx-2025-en-r&anchor=para_23_d&doctype=Standard
-URIDate 2025-03-27

+ Details

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

- References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Note Expiry date 2027-01-01
-Name IAS
-Number 1
-IssueDate 2025-01-01
-Paragraph 112
-Subparagraph c
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2025-en-b&anchor=para_112_c&doctype=Standard
-URIDate 2025-03-27

+ Details

Name:	ifrs-full_InterestIncomeOnCashAndCashEquivalents
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- References

+ Details

Name:	ifrs-full_InterestIncomeOnDeposits
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The losses resulting from changes in the fair value of derivatives recognised in profit or loss. [Refer: Derivatives [member]]

+ References

+ Details

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

- References

+ Details

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

- References

+ Details

Name:	ifrs-full_OtherFinanceIncome
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table.

+ References

No definition available.

+ Details

Name:	iva_FinancialIncomeAndExpensesLineItems
Namespace Prefix:	iva_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	ifrs-full_ClassesOfFinancialLiabilitiesAxis=iva_EuropeanInvestmentBankWarrantsTrancheaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_ClassesOfFinancialLiabilitiesAxis=iva_EuropeanInvestmentBankWarrantsTrancheBMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_ClassesOfFinancialLiabilitiesAxis=iva_T2NewSharesAndT2BsasCallOptionsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_BorrowingsByNameAxis=iva_FinanceContractWithEuropeanInvestmentBankMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_BorrowingsByNameAxis=iva_FinanceContractWithEuropeanInvestmentBankFirstTrancheMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_BorrowingsByNameAxis=iva_FinanceContractWithEuropeanInvestmentBankSecondTrancheMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_BorrowingsByNameAxis=iva_RoyaltyCertificateLiabilitiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_BorrowingsByNameAxis=iva_RoyaltyCertificates2024Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_BorrowingsByNameAxis=iva_RoyaltyCertificates2023Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_BorrowingsByNameAxis=iva_PgeLoansPprLoansAndBankOverdraftsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_BorrowingsByNameAxis=ifrs-full_LeaseLiabilitiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Financial income and expenses (Details) - EUR (€) € in Thousands	2 Months Ended	12 Months Ended
	Dec. 19, 2024	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Financial income and expenses
Income from cash equivalents		€ 2,945	€ 1,143	€ 991
Foreign exchange gains		1,225	1,715	797
Other financial income			30
Total financial income		4,169	2,888	1,788
Interest cost		(33,564)	(12,178)	(5,178)
Foreign exchange losses		(3,524)	(1,035)	(1,269)
Losses on fair value variation		(179,774)	(75,641)	(389)
Other financial expenses		(59)	(64)	(46)
Total financial expenses		(216,922)	(88,917)	(6,882)
Financial income (loss)		(212,752)	(86,029)	(5,095)
Interest income on deposits		2,900	1,100
EIB Warrants Tranche A
Financial income and expenses
Losses on fair value variation		(49,000)	(1,700)
EIB Warrants Tranche B
Financial income and expenses
Losses on fair value variation		(46,100)	(500)
T2 New Shares and T2 BSAs
Financial income and expenses
Losses on fair value variation	€ (89,400)	(84,700)
Gain on fair value variation			16,000
Finance contract with EIB
Financial income and expenses
Interest cost		(9,300)	(8,300)	(3,400)
Finance contract with EIB, first tranche (Tranche A)
Financial income and expenses
Interest cost		(5,000)	(4,200)
Finance contract with EIB, second tranche (Tranche B)
Financial income and expenses
Interest cost		(4,300)	(4,100)
Royalty Certificate
Financial income and expenses
Interest cost		(22,400)	(3,200)	(400)
2024 Royalty Certificates
Financial income and expenses
Interest cost		(17,400)	(1,500)
2023 Royalty Certificates
Financial income and expenses
Interest cost		€ (5,000)	(1,700)
PGE loans, the PPR loans; and interests on bank overdrafts
Financial income and expenses
Interest cost			(300)
Lease liabilities
Financial income and expenses
Interest cost			€ (200)	€ (200)