Name:	crv_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonvestedOptionsForfeitedInPeriodWeightedAverageGrantDateFairValue
Namespace Prefix:	crv_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

Share Based Compensation Arrangement by Share Based Payment Award, Nonvested Options, Granted in Period, Weighted Average Grant Date Fair Value

No definition available.

Name:	crv_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonvestedOptionsGrantedInPeriodWeightedAverageGrantDateFairValue
Namespace Prefix:	crv_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

Share Based Compensation Arrangement by Share Based Payment Award, Nonvested Options, Vested in Period, Weighted Average Grant Date Fair Value

No definition available.

Name:	crv_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonvestedOptionsVestedInPeriodWeightedAverageGrantDateFairValue
Namespace Prefix:	crv_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	crv_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsNonvestedRollForward
Namespace Prefix:	crv_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Share based Compensation Arrangement by Share based Payment Award, Options Nonvested, Weighted Average Grant Date Fair Value

No definition available.

Name:	crv_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValue
Namespace Prefix:	crv_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	crv_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValueAbstract
Namespace Prefix:	crv_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number, Nonvested

No definition available.

Name:	crv_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingNumberNonvested
Namespace Prefix:	crv_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

Share Based Compensation Arrangement by Share Based Payment Award, Options, Vested in Period

No definition available.

Name:	crv_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedInPeriod
Namespace Prefix:	crv_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(1)(iv)(3)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph b(1)(f)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

Net number of share options (or share units) granted during the period.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(1)(iv)(1)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph b(1)(d)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.