The number of renewable terms for an operating lease.

No definition available.

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

- Definition

Number of operating lease.

+ References

No definition available.

+ Details

Name:	cara_NumberOfOperatingLease
Namespace Prefix:	cara_
Data Type:	xbrli:integerItemType
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

No definition available.

+ Details

Name:	us-gaap_LesseeLeaseDescriptionLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Discount rate used by lessee to determine present value of operating lease payments.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (c)(3)
-URI https://asc.fasb.org/extlink&oid=128292326&loc=SL77918673-209980

+ Details

Name:	us-gaap_LesseeOperatingLeaseDiscountRate
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- 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
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)(3)
-URI https://asc.fasb.org/extlink&oid=128292326&loc=SL77918673-209980

+ Details

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

- Details

Name:	srt_CounterpartyNameAxis=cara_StamfordOperatingLeaseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CounterpartyNameAxis=cara_NewStamfordLeaseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CounterpartyNameAxis=cara_StamfordLeaseAndNewStamfordLeaseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AdjustmentsForNewAccountingPronouncementsAxis=us-gaap_AccountingStandardsUpdate201602Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Summary of Significant Accounting Policies - Leases (Details)	1 Months Ended	12 Months Ended
	Jun. 30, 2020 item	Dec. 31, 2022 item lease	Dec. 31, 2021 lease
Stamford Operating Lease [Member]
Lessee, Lease, Description [Line Items]
Number of renewable terms		1
Operating Lease, renewable term		5 years
New Stamford Lease [Member]
Lessee, Lease, Description [Line Items]
Number of renewable terms	1	1
Operating Lease, renewable term	5 years	5 years
Lessee Operating Lease Discount Rate		7.00%
Stamford Operating Lease and New Stamford Lease [Member]
Lessee, Lease, Description [Line Items]
Lessee Operating Lease Discount Rate		7.00%	7.00%
ASC 842 [Member] \| New Stamford Lease [Member]
Lessee, Lease, Description [Line Items]
Number of renewable terms		1
Operating Lease, renewable term		5 years
ASC 842 [Member] \| Stamford Operating Lease and New Stamford Lease [Member]
Lessee, Lease, Description [Line Items]
Number Of Operating Lease \| lease		2	2
Lessee Operating Lease Discount Rate		7.00%