Disclosure of information about consolidated and non-consolidated structured entities.

No definition available.

Name:	clls_DisclosureOfInformationAboutConsolidatedAndNonConsolidatedStructuredEntitiesLineItems
Namespace Prefix:	clls_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum number of exclusive license for product candidates.

+ References

No definition available.

+ Details

Name:	clls_MaximumNumberOfExclusiveLicenseForProductCandidates
Namespace Prefix:	clls_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of ordinary shares received.

+ References

No definition available.

+ Details

Name:	clls_NumberOfOrdinarySharesReceived
Namespace Prefix:	clls_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage Of Shareholding Diluted Of Merged Entity

+ References

No definition available.

+ Details

Name:	clls_PercentageOfShareholdingDilutedOfMergedEntity
Namespace Prefix:	clls_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The name of an associate. [Refer: Associates [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 27
-IssueDate 2023-01-01
-Paragraph 17
-Subparagraph b
-Clause i
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=27&code=ifrs-tx-2023-en-r&anchor=para_17_b_i&doctype=Standard
-URIDate 2023-03-23

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 27
-IssueDate 2023-01-01
-Paragraph 16
-Subparagraph b
-Clause i
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=27&code=ifrs-tx-2023-en-r&anchor=para_16_b_i&doctype=Standard
-URIDate 2023-03-23

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 12
-IssueDate 2023-01-01
-Paragraph 21
-Subparagraph a
-Clause i
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=12&code=ifrs-tx-2023-en-r&anchor=para_21_a_i&doctype=Standard
-URIDate 2023-03-23

+ Details

Name:	ifrs-full_NameOfAssociate
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of shares issued by the entity.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 1
-IssueDate 2023-01-01
-Paragraph 106
-Subparagraph d
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2023-en-r&anchor=para_106_d&doctype=Standard
-URIDate 2023-03-23

+ Details

Name:	ifrs-full_NumberOfSharesIssued
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

The proportion of ownership interest in an associate attributable to the entity. [Refer: Associates [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 27
-IssueDate 2023-01-01
-Paragraph 17
-Subparagraph b
-Clause iii
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=27&code=ifrs-tx-2023-en-r&anchor=para_17_b_iii&doctype=Standard
-URIDate 2023-03-23

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 27
-IssueDate 2023-01-01
-Paragraph 16
-Subparagraph b
-Clause iii
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=27&code=ifrs-tx-2023-en-r&anchor=para_16_b_iii&doctype=Standard
-URIDate 2023-03-23

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 12
-IssueDate 2023-01-01
-Paragraph 21
-Subparagraph a
-Clause iv
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=12&code=ifrs-tx-2023-en-r&anchor=para_21_a_iv&doctype=Standard
-URIDate 2023-03-23

+ Details

Name:	ifrs-full_ProportionOfOwnershipInterestInAssociate
Namespace Prefix:	ifrs-full_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The proportion of ownership interest in a subsidiary attributable to the entity. [Refer: Subsidiaries [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 27
-IssueDate 2023-01-01
-Paragraph 17
-Subparagraph b
-Clause iii
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=27&code=ifrs-tx-2023-en-r&anchor=para_17_b_iii&doctype=Standard
-URIDate 2023-03-23

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 27
-IssueDate 2023-01-01
-Paragraph 16
-Subparagraph b
-Clause iii
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=27&code=ifrs-tx-2023-en-r&anchor=para_16_b_iii&doctype=Standard
-URIDate 2023-03-23

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 12
-IssueDate 2023-01-01
-Paragraph 19B
-Subparagraph c
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=12&code=ifrs-tx-2023-en-r&anchor=para_19B_c&doctype=Standard
-URIDate 2023-03-23

+ Details

Name:	ifrs-full_ProportionOfOwnershipInterestInSubsidiary
Namespace Prefix:	ifrs-full_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The proportion of ownership interests in a subsidiary held by non-controlling interests. [Refer: Subsidiaries [member]; Non-controlling interests]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 12
-IssueDate 2023-01-01
-Paragraph 12
-Subparagraph c
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=12&code=ifrs-tx-2023-en-r&anchor=para_12_c&doctype=Standard
-URIDate 2023-03-23

+ Details

Name:	ifrs-full_ProportionOfOwnershipInterestsHeldByNoncontrollingInterests
Namespace Prefix:	ifrs-full_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The proportion of the voting rights in an associate held by the entity. [Refer: Associates [member]]

+ References

+ Details

Name:	ifrs-full_ProportionOfVotingPowerHeldInAssociate
Namespace Prefix:	ifrs-full_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	ifrs-full_CategoriesOfRelatedPartiesAxis=clls_CibusGlobalLlcMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_ClassesOfShareCapitalAxis=clls_ClassACommonStockMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_SignificantInvestmentsInSubsidiariesAxis=clls_CellectisIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_CategoriesOfRelatedPartiesAxis=clls_CellectisBiologicsIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_SignificantInvestmentsInSubsidiariesAxis=clls_CalyxtMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_SignificantInvestmentsInAssociatesAxis=clls_PrimeraTherapeuticsIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_SegmentsAxis=clls_CalyxtAtmProgramMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Scope of Consolidation and Non-Consolidated Entities - Additional Information (Detail)						1 Months Ended	6 Months Ended	12 Months Ended
	Jun. 01, 2023	May 31, 2023 shares	May 17, 2023 shares	Dec. 29, 2022 Product	Nov. 23, 2022	Jun. 30, 2023	Jun. 30, 2023	Dec. 31, 2022
Disclosure of Information about Consolidated and Non-consolidated Structured Entities [Line Items]
Ownership interest in subsidiary						100.00%
Percentage of shareholding diluted of merged entity					2.40%
Cibus Global [Member]
Disclosure of Information about Consolidated and Non-consolidated Structured Entities [Line Items]
Ownership interest in subsidiary	2.90%
Cibus Global [Member] \| Class A Common Stock [Member]
Disclosure of Information about Consolidated and Non-consolidated Structured Entities [Line Items]
Number of shares issued		16,527,484
Cellectis, Inc. [member]
Disclosure of Information about Consolidated and Non-consolidated Structured Entities [Line Items]
Ownership interest in subsidiary							100.00%
Cellectis, Inc. [member] \| Cellectis Biologics, Inc. [Member]
Disclosure of Information about Consolidated and Non-consolidated Structured Entities [Line Items]
Ownership interest in subsidiary							100.00%
Calyxt [member]
Disclosure of Information about Consolidated and Non-consolidated Structured Entities [Line Items]
Ownership interest in subsidiary		48.00%
Primera Therapeutics, Inc. [Member]
Disclosure of Information about Consolidated and Non-consolidated Structured Entities [Line Items]
Name of associate				Primera Therapeutics, Inc.
Maximum number of exclusive license for product candidates \| Product				5
Number of common stock received			234,570
Ownership interest in associate			19.00%				17.00%
Voting rights held in associate			19.00%				17.00%
Calyxt ATM Program [Member] \| Cellectis, Inc. [member]
Disclosure of Information about Consolidated and Non-consolidated Structured Entities [Line Items]
Non-controlling shareholders interest		52.00%						50.90%