Commitments and contingencies.

No definition available.

Name:	isco_CommitmentsAndContingenciesLineItems
Namespace Prefix:	isco_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Finance leases.

+ References

No definition available.

+ Details

Name:	isco_FinanceLeases
Namespace Prefix:	isco_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Lease expiration month and year.

+ References

No definition available.

+ Details

Name:	isco_LeaseExpirationMonthAndYear
Namespace Prefix:	isco_
Data Type:	xbrli:gYearMonthItemType
Balance Type:	na
Period Type:	duration

- Definition

Minimum license fee payable.

+ References

No definition available.

+ Details

Name:	isco_MinimumLicenseFeePayable
Namespace Prefix:	isco_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Notice of termination under license agreement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	isco_NoticeOfTerminationUnderLicenseAgreement
Namespace Prefix:	isco_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of installments per year.

+ References

No definition available.

+ Details

Name:	isco_NumberOfInstallmentsPerYear
Namespace Prefix:	isco_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of operating leases.

+ References

No definition available.

+ Details

Name:	isco_NumberOfOperatingLeases
Namespace Prefix:	isco_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of base rent abated.

+ References

No definition available.

+ Details

Name:	isco_PercentageOfBaseRentAbated
Namespace Prefix:	isco_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of increase rent per annum over lease term.

+ References

No definition available.

+ Details

Name:	isco_PercentageOfIncreaseRentPerAnnumOverLeaseTerm
Namespace Prefix:	isco_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Date which lease or group of leases is set to expire, in YYYY-MM-DD format.

+ References

No definition available.

+ Details

Name:	us-gaap_LeaseExpirationDate1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of single lease cost, calculated by allocation of remaining cost of lease over remaining lease term. Includes, but is not limited to, single lease cost, after impairment of right-of-use asset, calculated by amortization of remaining right-of-use asset and accretion of lease liability.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 55
-Paragraph 53
-URI http://asc.fasb.org/extlink&oid=123414884&loc=SL77918982-209971

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123408670&loc=SL77918686-209980

+ Details

Name:	us-gaap_OperatingLeaseCost
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of operating lease expense. Excludes sublease income.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 45
-Paragraph 4
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123391704&loc=SL77918638-209977

+ Details

Name:	us-gaap_OperatingLeaseExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	dei_LegalEntityAxis=isco_AstellasPharmaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

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

- Details

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

Commitments and Contingencies - Additional Information (Detail) $ in Thousands		1 Months Ended		3 Months Ended
	Nov. 01, 2021	Nov. 30, 2021 USD ($)	Oct. 31, 2021 USD ($)	Mar. 31, 2022 USD ($) Lease Installment	Mar. 31, 2021 USD ($)	Dec. 31, 2021 USD ($)
Commitments And Contingencies [Line Items]
Number of operating leases for real estate \| Lease				3
Expiry of lease	Dec. 31, 2026	Dec. 31, 2026
Base rent due under lease		$ 4	$ 11
Percentage of increase rent per annum over lease term	3.50%
Percentage of base rent abated of lease term	50.00%
Lease expense				$ 73	$ 118
Finance leases				0		$ 0
Astellas Pharma [Member]
Commitments And Contingencies [Line Items]
Minimum license fee payable				$ 75
Number of installments per year \| Installment				2
Notice of termination under license agreement				30 days
San Diego \| Corporate Headquarters [Member]
Commitments And Contingencies [Line Items]
Operating leases with term date				2026-12
San Diego \| Supplemental Office Space [Member]
Commitments And Contingencies [Line Items]
Operating leases with term date				2026-12
Frederick, Maryland [Member]
Commitments And Contingencies [Line Items]
Operating leases with term date				2025-12