v2.4.1.9

Subsequent Events - Additional Information (Detail) (Subsequent Event, USD $) In Millions, unless otherwise specified	0 Months Ended
	May 04, 2015	May 04, 2015
20th Amendment
Subsequent Event [Line Items]
Line of credit facility extended maturity date period	1 year
Revolving line of credit extended maturity date	Jul. 10, 2018
Maximum borrowings available under line of credit	$ 30us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity / crv_AmendmentAxis = crv_AmendedCreditFacilityMember / us-gaap_SubsequentEventTypeAxis = us-gaap_SubsequentEventMember	$ 30us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity / crv_AmendmentAxis = crv_AmendedCreditFacilityMember / us-gaap_SubsequentEventTypeAxis = us-gaap_SubsequentEventMember
Line of credit facility, reduction in interest rate	0.25%crv_LineOfCreditFacilityReductionInInterestRate / crv_AmendmentAxis = crv_AmendedCreditFacilityMember / us-gaap_SubsequentEventTypeAxis = us-gaap_SubsequentEventMember	0.25%crv_LineOfCreditFacilityReductionInInterestRate / crv_AmendmentAxis = crv_AmendedCreditFacilityMember / us-gaap_SubsequentEventTypeAxis = us-gaap_SubsequentEventMember
Before Amendment
Subsequent Event [Line Items]
Revolving line of credit maturity date	Jul. 10, 2017

X

- Definition

Extended Line Of Credit Facility Expiration Date

+ References

No definition available.

+ Details

Name:	crv_ExtendedLineOfCreditFacilityExpirationDate
Namespace Prefix:	crv_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Line Of Credit Facility Extension In Maturity Period

+ References

No definition available.

+ Details

Name:	crv_LineOfCreditFacilityExtensionInMaturityPeriod
Namespace Prefix:	crv_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Line of Credit Facility, Reduction in Interest Rate

+ References

No definition available.

+ Details

Name:	crv_LineOfCreditFacilityReductionInInterestRate
Namespace Prefix:	crv_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

X

- Definition

Date the credit facility terminates, in CCYY-MM-DD format.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19(b),22(b))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682



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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

+ Details

Name:	us-gaap_LineOfCreditFacilityExpirationDate1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19(b),22(b))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682



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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Details

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