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Represents the required percentage of written consent or affirmative vote of all shares outstanding of securities classified as temporary equity to amend, alter or repeal the preferences, special rights or other powers of such securities.

No definition available.

Name:	coll_TemporaryEquityChangeInFeaturesWrittenConsentOrAffirmativeVoteOfOutstandingSharesPercentage
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Data Type:	num:percentItemType
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Period Type:	duration

The per share conversion price of stock classified as temporary equity.

No definition available.

Name:	coll_TemporaryEquityConvertibleConversionPrice
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Data Type:	num:perShareItemType
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Cumulative value of accretion of temporary equity due to unpaid dividends.

No definition available.

Name:	coll_TemporaryEquityCumulativeAccretionOfDividends
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Represents the original issue price per share of stock classified as temporary equity that has liquidation preference in the event of any voluntary or involuntary liquidation, dissolution or winding-up of the affairs of the entity or a Deemed Liquidation Event, as defined in the agreement to the financial instrument.

No definition available.

Name:	coll_TemporaryEquityLiquidationRightsOriginalIssuePricePerShare
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Data Type:	num:perShareItemType
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Ratio applied to the original issue price of stock classified as temporary equity that has liquidation preference in the event of any voluntary or involuntary liquidation, dissolution or winding-up of the affairs of the entity or a Deemed Liquidation Event, as defined in the agreement to the financial instrument.

No definition available.

Name:	coll_TemporaryEquityLiquidationRightsPerShareIssuePriceRatio
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Represents the required percentage of affirmative vote of all shares outstanding of securities classified as temporary equity to exercise for the holders to exercise the optional redemption feature on or after the date specified in the agreement to the financial instrument.

No definition available.

Name:	coll_TemporaryEquityOptionalRedemptionFeatureAffirmativeVoteOfOutstandingSharesPercentage
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Data Type:	num:percentItemType
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The number of installments in which an optional redemption of stock classified as temporary equity is to be paid.

No definition available.

Name:	coll_TemporaryEquityOptionalRedemptionFeatureNumberOfInstallmentPayments
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Ratio applied to the original issue price of stock classified as temporary equity in an optional redemption, as defined in the agreement to the financial instrument.

No definition available.

Name:	coll_TemporaryEquityOptionalRedemptionFeaturePerShareIssuePriceRatio
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Represents the number of directors the holders of record of securities classified as temporary equity are entitled to elect.

No definition available.

Name:	coll_TemporaryEquityRightsToElectDirectorsNumberOfDirectors
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The number of the entity's securities classified as temporary equity that are owned by a shareholder.

No definition available.

Name:	coll_TemporaryEquityShareholderSharesOwned
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Data Type:	xbrli:sharesItemType
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Value of decrease to temporary equity to its redemption value during the period for a modification of shares issued and outstanding.

No definition available.

Name:	coll_TemporaryEquityStockIssuedAndOutstandingModificationAdjustmentToRedemptionValue
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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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.

No definition available.

Name:	us-gaap_ClassOfStockLineItems
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The percentage rate used to calculate dividend payments on preferred stock.

No definition available.

Name:	us-gaap_PreferredStockDividendRatePercentage
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Data Type:	num:percentItemType
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Period Type:	duration

The cash inflow from the additional capital contribution to the entity.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Financing Activities
-URI http://asc.fasb.org/extlink&oid=6513228

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3255-108585

Name:	us-gaap_ProceedsFromIssuanceOfCommonStock
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Per share or per unit amount of equity securities issued.

No definition available.

Name:	us-gaap_SharesIssuedPricePerShare
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

Ratio applied to the conversion of stock split, for example but not limited to, one share converted to two or two shares converted to one.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SAB TOPIC 4.C)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187143-122770

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Stock Split
-URI http://asc.fasb.org/extlink&oid=6525746

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Data Type:	xbrli:pureItemType
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Name:	us-gaap_StatementEquityComponentsAxis=us-gaap_CommonStockMember
Namespace Prefix:
Data Type:	na
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Name:	us-gaap_StatementClassOfStockAxis=us-gaap_RedeemableConvertiblePreferredStockMember
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Data Type:	na
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Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
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Data Type:	na
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Name:	us-gaap_StatementScenarioAxis=coll_ConvertibleFinancialInstrumentMandatoryConversionCompletionOfInitialPublicOfferingMember
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Data Type:	na
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Name:	us-gaap_StatementScenarioAxis=coll_ConvertibleFinancialInstrumentAutomaticConversionProvisionCompletionOfQualifiedFinancingMember
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Data Type:	na
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Name:	us-gaap_StatementClassOfStockAxis=us-gaap_SeriesAPreferredStockMember
Namespace Prefix:
Data Type:	na
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Name:	us-gaap_StatementClassOfStockAxis=us-gaap_SeriesBPreferredStockMember
Namespace Prefix:
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