Amount reclassified from collaborative revenue to clinical compound revenue.

No definition available.

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of cost incurred in the period related to clinical trials included in the research and development deliverable under the Maruishi license agreement.

+ References

No definition available.

+ Details

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

- Definition

Amount of revenue recognized in the period from the revenue deferred upon initiation of the Maruishi license agreement. The amount recognized is based on the amount of research and development costs incurred during the period as a percentage of total such costs expected to be incurred to fulfill the research and development deliverable.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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- Definition

Cash received upon entering into a license agreement with a collaborator combined with cash received upon achievement of a defined milestone by the collaborator.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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- Definition

Maximum potential revenue to be recognized if all defined milestones that are to be achieved under the license agreement by the collaborator are actually achieved.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
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- Definition

Maximum potential revenue to be recognized if all defined milestones that are to be achieved by the company under the license agreement are actually achieved.

+ References

No definition available.

+ Details

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Namespace Prefix:	cara_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The amount that could be received by the company if Maruishi achieves the next clinical development milestone defined in the Maruishi license agreement.

+ References

No definition available.

+ Details

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

- Definition

Number of items that the company is contractually required to provide to the licensee during the term of the license. Revenue recognized by the company is apportioned among the identified deliverables.

+ References

No definition available.

+ Details

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

- 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

No definition available.

+ Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The carrying amount of consideration received or receivable as of the balance sheet date on potential earnings that were not recognized as revenue in conformity with GAAP, and which are expected to be recognized as such within one year or the normal operating cycle, if longer, including sales, license fees, and royalties, but excluding interest income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section 45

-Paragraph 8

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=28358313&loc=d3e6935-107765

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 605

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SAB TOPIC 13.A.4(a).Q1)

-URI http://asc.fasb.org/extlink&oid=27012821&loc=d3e214044-122780

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 13

-Section A

+ Details

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

- Details

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- Details

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- Details

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Collaborations - Additional Information (Detail) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($) Deliverables	Jun. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Deferred R&D service revenue	$ 89		$ 89		$ 1,452
License and milestone fee revenue		$ 302		$ 302
Collaborative revenue	874	526	$ 1,363	677
Revenue recognized from sale of clinical compound		132		159
Maruishi License Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Number of deliverables for revenue recognized \| Deliverables			2
Clinical trial costs related to the R&D services deliverable	877	714	$ 1,475	1,112
Maruishi Pharmaceutical Co., Ltd. [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenue recognized from nonsubstantive milestones			8,000
Revenue recognized from substantive milestones			2,500
Deferred R&D service revenue	89		89		$ 1,452
License and milestone fee revenue	0	302	0	302
Collaborative revenue	874	526	1,363	677
Revenue recognized from sale of clinical compound	$ 0	$ 132	0	$ 159
Maruishi Pharmaceutical Co., Ltd. [Member] \| Clinical Development [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Next potential milestone that could be received			$ 2,000