Name:	cara_IncrementalCommonSharesAttributableToShareBasedCompensationArrangementsOptions
Namespace Prefix:	cara_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of restricted stock units using the treasury stock method.

No definition available.

Name:	cara_IncrementalCommonSharesAttributableToShareBasedCompensationArrangementsRestrictedStockUnits
Namespace Prefix:	cara_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

The amount of potential milestone payment of common stock investment.

No definition available.

Name:	cara_PotentialMilestonePayment
Namespace Prefix:	cara_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The percentage of Premium on Common Stock Investment.

No definition available.

Name:	cara_PremiumOnCommonStockInvestmentPercentage
Namespace Prefix:	cara_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

The length of time used to measure the trailing average price of stock to set the price in issuing stock as part of the Vifor Agreement.

No definition available.

Name:	cara_StockIssuancePriceMeasurementPeriod
Namespace Prefix:	cara_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(i)-(ii)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

Number of options outstanding, including both vested and non-vested options.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(i)-(ii)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901