v2.4.1.9

Summary of Fair Value Measurement of Financial Assets (Detail) (Short Term Investments and Cash Equivalents, USD $) In Thousands, unless otherwise specified | Dec. 31, 2013
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Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
Cash equivalents - Overnight Investments | $ 1,623 crv_CashCashEquivalentsAndInvestmentsFairValueDisclosure
Fair Value, Inputs, Level 2 |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
Cash equivalents - Overnight Investments | $ 1,623 crv_CashCashEquivalentsAndInvestmentsFairValueDisclosure / us-gaap_FairValueByAssetClassAxis = crv_ShortTermInvestmentsAndCashEquivalentsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member

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- Definition Cash Cash Equivalents And Investments Fair Value Disclosure + References No definition available. + Details
Name: | crv_CashCashEquivalentsAndInvestmentsFairValueDisclosure
Namespace Prefix: | crv_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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- Details
Name: | us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |