Area of land surrendered.

No definition available.

Name:	iova_AreaOfLandSurrendered
Namespace Prefix:	iova_
Data Type:	dtr-types:areaItemType
Balance Type:	na
Period Type:	instant

- Definition

mount of derecognition of lease liabilities at the time of termination or modification of lease agreement.

+ References

No definition available.

+ Details

Name:	iova_DerecognitionOfOperatingLeaseLiabilities
Namespace Prefix:	iova_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of derecognition of right of use assets at the time of termination or modification of lease agreement.

+ References

No definition available.

+ Details

Name:	iova_DerecognitionOfOperatingLeaseRightOfUseAssets
Namespace Prefix:	iova_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The aggregate amount of write-downs for impairments recognized during the period for long lived assets due to early termination of lease.

+ References

No definition available.

+ Details

Name:	iova_ImpairmentOfLongLivedAssetsDueToEarlyTerminationOfLease
Namespace Prefix:	iova_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount of cash outflow associated with the payment of related brokerage fees.

+ References

No definition available.

+ Details

Name:	iova_LesseeOperatingLeaseAmountOfBrokerageFeePaid
Namespace Prefix:	iova_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The amount of cash outflow associated with the payment of early termination.

+ References

No definition available.

+ Details

Name:	iova_LesseeOperatingLeaseAmountOfEarlyLeaseTerminationFeesPaid
Namespace Prefix:	iova_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Percentage of increase in monthly base rent of lease from its current amount under extension option.

+ References

No definition available.

+ Details

Name:	iova_LesseeOperatingLeaseExtensionPercentageOfIncreaseInMonthlyBaseRent
Namespace Prefix:	iova_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The amount of monthly base rent under operating lease of lessee.

+ References

No definition available.

+ Details

Name:	iova_LesseeOperatingLeaseMonthlyBaseRent
Namespace Prefix:	iova_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Number of options to extend the lease.

+ References

No definition available.

+ Details

Name:	iova_LesseeOperatingLeaseNumberOfOptionsToExtendLease
Namespace Prefix:	iova_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Area of land held.

+ References

No definition available.

+ Details

Name:	us-gaap_AreaOfLand
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:areaItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of gain (loss) on termination of lease before expiration of lease term.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 40
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479092/842-20-40-1

+ Details

Name:	us-gaap_GainLossOnTerminationOfLease
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Indicates (true false) whether lessee has option to extend operating lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478964/842-20-50-3

+ Details

Name:	us-gaap_LesseeOperatingLeaseExistenceOfOptionToExtend
Namespace Prefix:	us-gaap_
Data Type:	xbrli:booleanItemType
Balance Type:	na
Period Type:	duration

- Definition

Description of terms and conditions of option to extend lessee's operating lease. Includes, but is not limited to, information about option recognized as part of right-of-use asset and lease liability.

+ References

+ Details

Name:	us-gaap_LesseeOperatingLeaseOptionToExtend
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Term of lessee's operating lease renewal, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478964/842-20-50-3

+ Details

Name:	us-gaap_LesseeOperatingLeaseRenewalTerm
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

- Definition

Term of lessee's operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

+ Details

Name:	us-gaap_LesseeOperatingLeaseTermOfContract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of lessee's right to use underlying asset under operating lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479041/842-20-45-1

+ Details

Name:	us-gaap_OperatingLeaseRightOfUseAsset
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=iova_OfficeSpaceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementGeographicalAxis=iova_PhiladelphiaPennsylvaniaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_FurnitureAndFixturesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LeaseContractualTermAxis=iova_NewHeadquartersLeaseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementGeographicalAxis=iova_SanCarlosCaliforniaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LeaseContractualTermAxis=iova_SubLeaseAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

LEASES - Additional information (Details) $ in Thousands		3 Months Ended
LEASES - Additional information (Details) $ in Thousands	Nov. 15, 2024 USD ($) ft² item	Mar. 31, 2025 USD ($) ft²	Dec. 31, 2024 USD ($)
Option to extend		true
Operating lease right-of-use assets		$ 50,903	$ 55,201
Minimum
Term of contract in years		1 year
Maximum
Term of contract in years		16 years
Office Space \| Minimum
Term of contract in years		12 months
Office Space \| Philadelphia, Pennsylvania
Area of land \| ft²		136,000
Furniture and equipment \| Maximum
Term of contract in years		12 months
New Headquarters Lease \| Office Space \| San Carlos, California
Area of land surrendered \| ft²	49,918
Early termination payment	$ 600
Brokerage fees paid	2,500
Derecognition of operating lease right-of-use assets	13,700
Derecognition of operating lease liabilities	22,300
Gain on termination of lease	8,600
Impairment due to early termination	$ 7,400
Sub Lease Agreement \| Office Space \| San Carlos, California
Area of land \| ft²	16,731
Term of contract in years	24 months
Number of options to extend the lease \| item	2
Existence of option to extend lease	true
Renewal term in years	12 months
Percentage of increase in monthly base rent upon extension	3.00%
Monthly base rent	$ 100
Operating lease right-of-use assets	$ 2,300