The number of renewal periods available under the lease.

No definition available.

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Namespace Prefix:	coll_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Annual base rent of operating lease.

+ References

No definition available.

+ Details

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Namespace Prefix:	coll_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Percentage of operating lease increased annually.

+ References

No definition available.

+ Details

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Namespace Prefix:	coll_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Area of a real estate property.

+ References

No definition available.

+ Details

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

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 7A
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478964/842-20-50-7A

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478964/842-20-50-3

+ Details

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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

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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

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

- Definition

Present value of lessee's discounted obligation for lease payments from 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 (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479041/842-20-45-1

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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

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

- Details

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

- Details

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- Details

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- Details

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Leases - Operating Lease Arrangements (Details) $ in Thousands	1 Months Ended
	Mar. 31, 2018 USD ($) ft² item	Dec. 31, 2024 USD ($) ft²	Dec. 31, 2023 USD ($)	Dec. 31, 2018
Lessee, Lease, Description [Line Items]
Operating lease assets		$ 5,822	$ 6,029
Operating lease liabilities		$ 6,810
Vehicle leases
Lessee, Lease, Description [Line Items]
Lease term				12 months
Stoughton, Massachusetts
Lessee, Lease, Description [Line Items]
Square of feet of space \| ft²	50,678
Lease term	10 years
Number of renewal periods \| item	2
Term of lease extension option	5 years
Base rent	$ 1,214
Durham, North Carolina
Lessee, Lease, Description [Line Items]
Square of feet of space \| ft²		8,817
Maximum \| Stoughton, Massachusetts
Lessee, Lease, Description [Line Items]
Increase in annual base rent	3.10%
Minimum \| Stoughton, Massachusetts
Lessee, Lease, Description [Line Items]
Increase in annual base rent	2.50%