v2.4.1.9

Valuation and Qualifying Accounts (Detail) (USD $) | 12 Months Ended
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Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012
Allowance for Doubtful Accounts |  |  |  |  |
Valuation and Qualifying Accounts Disclosure [Line Items] |  |  |  |  |
Balance at Beginning of Period | $ 278,000 us-gaap_ValuationAllowancesAndReservesBalance / us-gaap_ValuationAllowancesAndReservesTypeAxis = us-gaap_AllowanceForDoubtfulAccountsMember |  | $ 311,000 us-gaap_ValuationAllowancesAndReservesBalance / us-gaap_ValuationAllowancesAndReservesTypeAxis = us-gaap_AllowanceForDoubtfulAccountsMember |  | $ 387,000 us-gaap_ValuationAllowancesAndReservesBalance / us-gaap_ValuationAllowancesAndReservesTypeAxis = us-gaap_AllowanceForDoubtfulAccountsMember
Adjustments | 88,000 us-gaap_ValuationAllowancesAndReservesAdjustments / us-gaap_ValuationAllowancesAndReservesTypeAxis = us-gaap_AllowanceForDoubtfulAccountsMember |  | 115,000 us-gaap_ValuationAllowancesAndReservesAdjustments / us-gaap_ValuationAllowancesAndReservesTypeAxis = us-gaap_AllowanceForDoubtfulAccountsMember |  | 23,000 us-gaap_ValuationAllowancesAndReservesAdjustments / us-gaap_ValuationAllowancesAndReservesTypeAxis = us-gaap_AllowanceForDoubtfulAccountsMember
Deductions | (141,000)us-gaap_ValuationAllowancesAndReservesDeductions / us-gaap_ValuationAllowancesAndReservesTypeAxis = us-gaap_AllowanceForDoubtfulAccountsMember |  | (148,000)us-gaap_ValuationAllowancesAndReservesDeductions / us-gaap_ValuationAllowancesAndReservesTypeAxis = us-gaap_AllowanceForDoubtfulAccountsMember |  | (99,000)us-gaap_ValuationAllowancesAndReservesDeductions / us-gaap_ValuationAllowancesAndReservesTypeAxis = us-gaap_AllowanceForDoubtfulAccountsMember
Balance at End of Period | 225,000 us-gaap_ValuationAllowancesAndReservesBalance / us-gaap_ValuationAllowancesAndReservesTypeAxis = us-gaap_AllowanceForDoubtfulAccountsMember |  | 278,000 us-gaap_ValuationAllowancesAndReservesBalance / us-gaap_ValuationAllowancesAndReservesTypeAxis = us-gaap_AllowanceForDoubtfulAccountsMember |  | 311,000 us-gaap_ValuationAllowancesAndReservesBalance / us-gaap_ValuationAllowancesAndReservesTypeAxis = us-gaap_AllowanceForDoubtfulAccountsMember
Allowance for Obsolete or Slow-Moving Inventory |  |  |  |  |
Valuation and Qualifying Accounts Disclosure [Line Items] |  |  |  |  |
Balance at Beginning of Period | 1,454,000 us-gaap_ValuationAllowancesAndReservesBalance / us-gaap_ValuationAllowancesAndReservesTypeAxis = crv_AllowanceForObsoleteOrSlowMovingInventoryMember |  | 1,439,000 us-gaap_ValuationAllowancesAndReservesBalance / us-gaap_ValuationAllowancesAndReservesTypeAxis = crv_AllowanceForObsoleteOrSlowMovingInventoryMember |  | 1,401,000 us-gaap_ValuationAllowancesAndReservesBalance / us-gaap_ValuationAllowancesAndReservesTypeAxis = crv_AllowanceForObsoleteOrSlowMovingInventoryMember
Adjustments | 176,000 us-gaap_ValuationAllowancesAndReservesAdjustments / us-gaap_ValuationAllowancesAndReservesTypeAxis = crv_AllowanceForObsoleteOrSlowMovingInventoryMember |  | 251,000 us-gaap_ValuationAllowancesAndReservesAdjustments / us-gaap_ValuationAllowancesAndReservesTypeAxis = crv_AllowanceForObsoleteOrSlowMovingInventoryMember |  | 224,000 us-gaap_ValuationAllowancesAndReservesAdjustments / us-gaap_ValuationAllowancesAndReservesTypeAxis = crv_AllowanceForObsoleteOrSlowMovingInventoryMember
Deductions | (235,000)us-gaap_ValuationAllowancesAndReservesDeductions / us-gaap_ValuationAllowancesAndReservesTypeAxis = crv_AllowanceForObsoleteOrSlowMovingInventoryMember |  | (236,000)us-gaap_ValuationAllowancesAndReservesDeductions / us-gaap_ValuationAllowancesAndReservesTypeAxis = crv_AllowanceForObsoleteOrSlowMovingInventoryMember |  | (186,000)us-gaap_ValuationAllowancesAndReservesDeductions / us-gaap_ValuationAllowancesAndReservesTypeAxis = crv_AllowanceForObsoleteOrSlowMovingInventoryMember
Balance at End of Period | 1,395,000 us-gaap_ValuationAllowancesAndReservesBalance / us-gaap_ValuationAllowancesAndReservesTypeAxis = crv_AllowanceForObsoleteOrSlowMovingInventoryMember |  | 1,454,000 us-gaap_ValuationAllowancesAndReservesBalance / us-gaap_ValuationAllowancesAndReservesTypeAxis = crv_AllowanceForObsoleteOrSlowMovingInventoryMember |  | 1,439,000 us-gaap_ValuationAllowancesAndReservesBalance / us-gaap_ValuationAllowancesAndReservesTypeAxis = crv_AllowanceForObsoleteOrSlowMovingInventoryMember
Valuation Allowance of Deferred Tax Assets |  |  |  |  |
Valuation and Qualifying Accounts Disclosure [Line Items] |  |  |  |  |
Balance at Beginning of Period | 1,369,000 us-gaap_ValuationAllowancesAndReservesBalance / us-gaap_ValuationAllowancesAndReservesTypeAxis = us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember |  | 1,376,000 us-gaap_ValuationAllowancesAndReservesBalance / us-gaap_ValuationAllowancesAndReservesTypeAxis = us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember |  | 1,213,000 us-gaap_ValuationAllowancesAndReservesBalance / us-gaap_ValuationAllowancesAndReservesTypeAxis = us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember
Additions |  |  |  |  | 163,000 crv_ValuationAllowancesAndReservesAdditions / us-gaap_ValuationAllowancesAndReservesTypeAxis = us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember
Deductions | (15,000)us-gaap_ValuationAllowancesAndReservesDeductions / us-gaap_ValuationAllowancesAndReservesTypeAxis = us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember | [1] | (7,000)us-gaap_ValuationAllowancesAndReservesDeductions / us-gaap_ValuationAllowancesAndReservesTypeAxis = us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember | [1] |
Balance at End of Period | $ 1,354,000 us-gaap_ValuationAllowancesAndReservesBalance / us-gaap_ValuationAllowancesAndReservesTypeAxis = us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember |  | $ 1,369,000 us-gaap_ValuationAllowancesAndReservesBalance / us-gaap_ValuationAllowancesAndReservesTypeAxis = us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember |  | $ 1,376,000 us-gaap_ValuationAllowancesAndReservesBalance / us-gaap_ValuationAllowancesAndReservesTypeAxis = us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember
[1] | Net operating loss carryforwards used or expired.

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- Definition Total of the adjustments in a given period to allowances and reserves, the valuation and qualifying accounts that are either netted against the cost of an asset (in order to value it at its carrying value) or that reflect a liability. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24092-122690 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 09 -Article 12 + Details
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- Definition Total of allowances and reserves, the valuation and qualifying accounts that are either netted against the cost of an asset (in order to value it at its carrying value) or that reflect a liability established to represent expected future costs. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24092-122690 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 09 -Article 12 + Details
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- Definition Total of the deductions in a given period to allowances and reserves, the valuation and qualifying accounts that are either netted against the cost of an asset (in order to value it at its carrying value) or that reflect a liability established to represent expected future costs, representing receivables written off as uncollectible and portions of the reserves utilized, respectively. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24092-122690 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 09 -Article 12 + Details
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