Subsequent events (Details) - Subsequent events - Collaboration agreement with AbbVie $ in Millions	Jan. 04, 2023 USD ($)
Subsequent Event [Line Items]
Research term (in months)	66 months
Upfront payment	$ 30.0
Additional platform access payments	$ 70.0
Anniversary of first commerical sale (in years)	10 years
Maximum
Subsequent Event [Line Items]
Additional platform access payments	$ 70.0
Development and commercial sale milestone receivable per target	120.0
Sales based milestone based on achievement	150.0
Potentially eligible amount receivable	$ 2.8

The amount of additional platform access payments receivable.

No definition available.

Name:	imnm_AdditionalPlatformAccessPaymentReceivable
Namespace Prefix:	imnm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Potentially eligible amount receivable under the collaboration agreement.

+ References

No definition available.

+ Details

Name:	imnm_CollaborationAgreementPotentiallyEligibleAmountReceivable
Namespace Prefix:	imnm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The amount of cash inflow from non-refundable upfront payment.

+ References

No definition available.

+ Details

Name:	imnm_CollaborationArrangementProceedsFromNonRefundableUpfrontPayment
Namespace Prefix:	imnm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount of sales based milestone receivable upon achievement of target.

+ References

No definition available.

+ Details

Name:	imnm_CollaborativeArrangementSalesBasedMilestone
Namespace Prefix:	imnm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Term of research under the collaboration agreement.

+ References

No definition available.

+ Details

Name:	imnm_CollaborativeArrangementTermOfResearch
Namespace Prefix:	imnm_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of product development and commercial sale milestone receivable per target.

+ References

No definition available.

+ Details

Name:	imnm_CollaborativeArrangementsProductDevelopmentAndCommercialSaleMilestoneReceivablePerTarget
Namespace Prefix:	imnm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Term of anniversary for first commercial sale.

+ References

No definition available.

+ Details

Name:	imnm_TermOfAnniversaryForFirstCommercialSale
Namespace Prefix:	imnm_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

+ References

No definition available.

+ Details

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

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_TypeOfArrangementAxis=imnm_CollaborationAgreementWithAbbvieMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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